Yet Another Tire Size Question
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TrufflesEater
Dec 10, 2009, 4:08:40 AM12/10/09
to randon
Putting aside the "comfort" and performance aspects, do people who
have ridden both 28-30mm tires (on 700C wheels) and 38-42mm tires on
(on 650B wheels) feel the wider tires offer a greater margin of
safety, particularly on roads with poorly maintained pavement or
narrow lanes with rough/disappearing shoulders? If "yes," any idea
what the physical forces at play are?
David in Tokyo
have ridden both 28-30mm tires (on 700C wheels) and 38-42mm tires on
(on 650B wheels) feel the wider tires offer a greater margin of
safety, particularly on roads with poorly maintained pavement or
narrow lanes with rough/disappearing shoulders? If "yes," any idea
what the physical forces at play are?
David in Tokyo
Steve Palincsar
Dec 10, 2009, 7:13:45 AM12/10/09
to TrufflesEater, randon
into a huge pothole with the 38-42mm tires, a lot more cushion room
before the tire catches the tube against the inside of the rim. Also,
the wider tire has less chance of entering and getting caught in
longitudinal cracks in the road.
Ken Freeman
Dec 10, 2009, 8:35:32 AM12/10/09
to TrufflesEater, Steve Palincsar, randon
I think trail might have a lot to do with it, too. I've recently set up a vintage Peugeot UO-8 first, so it goes on a set of clean bearings, and with 700cX28s. On a few rides now it's showing itself to be very stable. It ignores pavement issues and longitudinal cracks, and tends to stay in a straight line. It's already quite easy to keep it on the fog line or near it. No-handed it tracks as if on rails, easily allowing glove changes and other fidgety tasks. It's real easy when there's not much room to run on. I haven't tried a front load yet. I don't have the Mafac brakes, so it's not easy to mount the rack. Still working on that.
So this is with 28 mm tires, Continental Ultra-Gatorskins. I think what's unique here are the large 70 mm fork rake and the resulting trail of 31 mm. The head angle is a little laid back, a little less than 73 degrees. The fork also has the deep French bend that seems to be more cushy, all by itself.
These benefits sound like what you might be looking for, and they're based on trail/rake, rather than the tire. I assume they'll be even better with the bigger tires that you are considering. I haven't had this bike out on any hard dirt roads yet. I know trail is a strong factor in how my Peug handles, because I've had those same wheels on several of my other bikes that have trail in the 55-60 mm range, and they have not shown this tremendous stability.
So, physical forces? I think in this case it's the mechanical leverage that are caused by road forces against the tire patch, and the low leverage that the tire patch has in rotating the fork assembly around the steering head. I don't see any convenient way of testing that hypothesis, however.
--
Ken Freeman
Ann Arbor, MI USA
So this is with 28 mm tires, Continental Ultra-Gatorskins. I think what's unique here are the large 70 mm fork rake and the resulting trail of 31 mm. The head angle is a little laid back, a little less than 73 degrees. The fork also has the deep French bend that seems to be more cushy, all by itself.
These benefits sound like what you might be looking for, and they're based on trail/rake, rather than the tire. I assume they'll be even better with the bigger tires that you are considering. I haven't had this bike out on any hard dirt roads yet. I know trail is a strong factor in how my Peug handles, because I've had those same wheels on several of my other bikes that have trail in the 55-60 mm range, and they have not shown this tremendous stability.
So, physical forces? I think in this case it's the mechanical leverage that are caused by road forces against the tire patch, and the low leverage that the tire patch has in rotating the fork assembly around the steering head. I don't see any convenient way of testing that hypothesis, however.
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Ken Freeman
Ann Arbor, MI USA
Steve Palincsar
Dec 10, 2009, 8:51:05 AM12/10/09
to Ken Freeman, TrufflesEater, randon
On Thu, 2009-12-10 at 08:35 -0500, Ken Freeman wrote:
> I think trail might have a lot to do with it, too. I've recently set
> up a vintage Peugeot UO-8 first, so it goes on a set of clean
> bearings, and with 700cX28s. On a few rides now it's showing itself
> to be very stable. It ignores pavement issues and longitudinal
> cracks, and tends to stay in a straight line.
I wasn't talking about tramlining, i.e., following the crack, but rather
> I think trail might have a lot to do with it, too. I've recently set
> up a vintage Peugeot UO-8 first, so it goes on a set of clean
> bearings, and with 700cX28s. On a few rides now it's showing itself
> to be very stable. It ignores pavement issues and longitudinal
> cracks, and tends to stay in a straight line.
literally falling into the crack and having the tire confront a "ledge"
or "wall" on either side.
I let a tire get into a crack like that between two lanes of concrete
paving (in the traffic circle around Mount Vernon) last December. The
result was an immediate crash. The same sort of crash has happened to
many of us when we've let our attention lapse and have gone off the side
of the road onto the shoulder: if you try to climb back up at an acute
angle, a crash is inevitable.
I am sure a wide enough tire will not tramline over a minor pavement
crack, it'll simply ignore it.
> It's already quite easy to keep it on the fog line or near it.
> No-handed it tracks as if on rails, easily allowing glove changes and
> other fidgety tasks. It's real easy when there's not much room to run
> on. I haven't tried a front load yet. I don't have the Mafac brakes,
> so it's not easy to mount the rack. Still working on that.
Velo Orange Randonneur, equipped with 32mm tires. Its handling is
precise (and precicely as noted in the Bicycle Quarterly review) and it
is quite easy to stay on the white line on the right hand side of the
road (we don't call it a "fog line" here in the East).
Tom Rosenbauer
Dec 10, 2009, 9:17:48 AM12/10/09
to TrufflesEater, randon
FWIW: Conti 700x23 4-Seasons, under inflated to 100 psi, give me a very
comfortable ride on all sorts of roads, and I haven't had a flat in at least
3000 miles ... but I still carry a spare tire with me... YMMV.
As an RBA, I see riders with all sorts of mechanical failures on brevets,
including tires ... one this year was about 20 feet down the driveway from
the start. Lucky for the rider who did not have a spare tire, I was able to
loan him one.
-Tom Rosenbauer
Eastern PA RBA
comfortable ride on all sorts of roads, and I haven't had a flat in at least
3000 miles ... but I still carry a spare tire with me... YMMV.
As an RBA, I see riders with all sorts of mechanical failures on brevets,
including tires ... one this year was about 20 feet down the driveway from
the start. Lucky for the rider who did not have a spare tire, I was able to
loan him one.
-Tom Rosenbauer
Eastern PA RBA
Wesley Cheney
Dec 10, 2009, 9:54:42 AM12/10/09
to randon
Tom Rosenbauer wrote:
FWIW: Conti 700x23 4-Seasons, under inflated to 100 psi, give me a very comfortable ride on all sorts of roads, and I haven't had a flat in at least @3000 miles.
Kudos, Tom, for finding a dependable tire I'm guessing that you weight a little less than I do: at 240 pounds (and 6'5") I also enjoyed 700x23 Conti tires. The problem was that I couldn't afford to keep buying new 28 spoke wheels...I would break a spoke or get a pinch flat every hundred miles, it seemed. The skinniest tire that I'll ride confidently now is 700x28, and I've developed a fondness for Schwalbe tires in the thirties: 32, 35, 38...etc...
So let's give tire size recommendations by rider weight.
Riders under five feet and a hundred pounds can ride comfortably on far skinnier tires, with fewer spoke & lighter rims. "Clydesdales" need wheelsets that are proprtionally bigger & stronger.
I've busted enough drive-side spokes on potholes that I'm now willing to forego skinnier "faster" tires for thicker "slower" tires. Those types of repairs cost both time & money.
Slow & Steady finishes the brevet!
Wes
*Stupid Hurts*
*Safety First*
FWIW: Conti 700x23 4-Seasons, under inflated to 100 psi, give me a very comfortable ride on all sorts of roads, and I haven't had a flat in at least @3000 miles.
Kudos, Tom, for finding a dependable tire I'm guessing that you weight a little less than I do: at 240 pounds (and 6'5") I also enjoyed 700x23 Conti tires. The problem was that I couldn't afford to keep buying new 28 spoke wheels...I would break a spoke or get a pinch flat every hundred miles, it seemed. The skinniest tire that I'll ride confidently now is 700x28, and I've developed a fondness for Schwalbe tires in the thirties: 32, 35, 38...etc...
So let's give tire size recommendations by rider weight.
Riders under five feet and a hundred pounds can ride comfortably on far skinnier tires, with fewer spoke & lighter rims. "Clydesdales" need wheelsets that are proprtionally bigger & stronger.
I've busted enough drive-side spokes on potholes that I'm now willing to forego skinnier "faster" tires for thicker "slower" tires. Those types of repairs cost both time & money.
Slow & Steady finishes the brevet!
Wes
*Stupid Hurts*
*Safety First*
Bob Riggs
Dec 10, 2009, 10:15:25 AM12/10/09
to randon
As Jan has pointed out many times, skinny tires are not necessarily
faster anyway. About a year ago I switched from UltraGator 25s at
105# to Pasela 28s or 32s at 90# (depending on whether I had fenders
on), and my cruising speed from start to finish immediately improved.
I made my choice based on an article in Bicycle Quarterly. Ride
comfort undoubtedly had something to do with it, but I think friction
on rough roads was more of a factor.
Of course, that's just one guy's experience. Still, my feeling is
that racers use skinny tires mostly as a weight-saving measure that
doesn't really apply to randonneuring.
On Dec 10, 8:54 am, Wesley Cheney <friend...@mac.com> wrote:
> Tom Rosenbauer wrote:
>
> FWIW: Conti 700x23 4-Seasons, under inflated to 100 psi, give me a very comfortable ride on all sorts of roads, and I haven't had a flat in at least @3000 miles.
>
> Kudos, Tom, for finding a dependable tire. I'm guessing that you weight a little less than I do: at 240 pounds (and 6'5") I also enjoyed 700x23 Conti tires. The problem was that I couldn't afford to keep buying new 28 spoke wheels...I would break a spoke or get a pinch flat every hundred miles, it seemed. The skinniest tire that I'll ride confidently now is 700x28, and I've developed a fondness for Schwalbe tires in the thirties: 32, 35, 38...etc...
>
> I've busted enough drive-side spokes on potholes that I'm now willing to forego skinnier "faster" tires for thicker "slower" tires. Those types of repairs cost both time & money.
>
> Slow & Steady finishes the brevet!
faster anyway. About a year ago I switched from UltraGator 25s at
105# to Pasela 28s or 32s at 90# (depending on whether I had fenders
on), and my cruising speed from start to finish immediately improved.
I made my choice based on an article in Bicycle Quarterly. Ride
comfort undoubtedly had something to do with it, but I think friction
on rough roads was more of a factor.
Of course, that's just one guy's experience. Still, my feeling is
that racers use skinny tires mostly as a weight-saving measure that
doesn't really apply to randonneuring.
On Dec 10, 8:54 am, Wesley Cheney <friend...@mac.com> wrote:
> Tom Rosenbauer wrote:
>
> FWIW: Conti 700x23 4-Seasons, under inflated to 100 psi, give me a very comfortable ride on all sorts of roads, and I haven't had a flat in at least @3000 miles.
>
>
> So let's give tire size recommendations by rider weight.
>
> Riders under five feet and a hundred pounds can ride comfortably on far skinnier tires, with fewer spoke & lighter rims. "Clydesdales" need wheelsets that are proprtionally bigger & stronger.
> So let's give tire size recommendations by rider weight.
>
>
> I've busted enough drive-side spokes on potholes that I'm now willing to forego skinnier "faster" tires for thicker "slower" tires. Those types of repairs cost both time & money.
>
> Slow & Steady finishes the brevet!
WMdeR
Dec 10, 2009, 11:48:38 AM12/10/09
to randon
Hi, All,
RE: margin of safety. In my opinion, a 42mm tire absolutely provides
a larger margin of safety than the 28-30mm tires. I use both 42-584
wheels and 28-622 wheels on my randonneuring machines.
The wider tires span cracks better, they climb the edge of road more
easily, they are not as easily diverted by train tracks etc, they're
significantly tougher and less likely to be damaged by road debris,
glass, or potholes, and they last substantially longer.
When combined with an appropriate geometry, they corner better and
handle as well. The prices I pay for that margin of safety and all
the other positive attributes of the wider tire: Acceleration, wheel
weight, and, according to the Bicycle Quarterly rolling resistance
tests, a penalty in rolling resistance on "average" roads. I do a two-
second cost/benefit analysis before each ride, and choose my machine
accordingly. It is often determined by which set of cleats I can find
in my closet first....
> > So let's give tire size recommendations by rider weight.
RE: minimum tire size by rider weight. One reasonable approach to
this issue is to look for a target tire pressure, say 85psi, that one
doesn't want to exceed. Determine one's wheel load (including all
your luggage, your bike, and you, fully clothed) then take a look at
F. Berto's tire-drop chart (check the archives for various links to
this chart).
I'd argue anything north of about 90psi is unnecessarily punishing you
and your equipment, but you get to choose the target tire pressure.
That'll tell you what the minimum tire size you'd want to ride. One
can always ride wider tires than the target at even lower tire
pressures for their comfort, safety, and other advantages, but
narrower would require higher (often much higher) tire pressures, and
that is harder on you and your equipment, and is likely slower on real-
world roads.
Then pick tires in your size range that meet your needs for rolling
resistance, durability, flat resistance, cost, etc.
Then you pays your money and you makes your choice.
Best Regards,
Will
William M. deRosset
RUSA 2401
RE: margin of safety. In my opinion, a 42mm tire absolutely provides
a larger margin of safety than the 28-30mm tires. I use both 42-584
wheels and 28-622 wheels on my randonneuring machines.
The wider tires span cracks better, they climb the edge of road more
easily, they are not as easily diverted by train tracks etc, they're
significantly tougher and less likely to be damaged by road debris,
glass, or potholes, and they last substantially longer.
When combined with an appropriate geometry, they corner better and
handle as well. The prices I pay for that margin of safety and all
the other positive attributes of the wider tire: Acceleration, wheel
weight, and, according to the Bicycle Quarterly rolling resistance
tests, a penalty in rolling resistance on "average" roads. I do a two-
second cost/benefit analysis before each ride, and choose my machine
accordingly. It is often determined by which set of cleats I can find
in my closet first....
> > So let's give tire size recommendations by rider weight.
this issue is to look for a target tire pressure, say 85psi, that one
doesn't want to exceed. Determine one's wheel load (including all
your luggage, your bike, and you, fully clothed) then take a look at
F. Berto's tire-drop chart (check the archives for various links to
this chart).
I'd argue anything north of about 90psi is unnecessarily punishing you
and your equipment, but you get to choose the target tire pressure.
That'll tell you what the minimum tire size you'd want to ride. One
can always ride wider tires than the target at even lower tire
pressures for their comfort, safety, and other advantages, but
narrower would require higher (often much higher) tire pressures, and
that is harder on you and your equipment, and is likely slower on real-
world roads.
Then pick tires in your size range that meet your needs for rolling
resistance, durability, flat resistance, cost, etc.
Then you pays your money and you makes your choice.
Best Regards,
Will
William M. deRosset
RUSA 2401
Steve Palincsar
Dec 10, 2009, 3:28:22 PM12/10/09
to WMdeR, randon
On Thu, 2009-12-10 at 08:48 -0800, WMdeR wrote:
> Hi, All,
>
> RE: margin of safety. In my opinion, a 42mm tire absolutely provides
> a larger margin of safety than the 28-30mm tires. I use both 42-584
> wheels and 28-622 wheels on my randonneuring machines.
>
> The wider tires span cracks better, they climb the edge of road more
> easily, they are not as easily diverted by train tracks etc, they're
> significantly tougher and less likely to be damaged by road debris,
> glass, or potholes, and they last substantially longer.
>
> When combined with an appropriate geometry, they corner better and
> handle as well. The prices I pay for that margin of safety and all
> the other positive attributes of the wider tire: Acceleration, wheel
> weight, and, according to the Bicycle Quarterly rolling resistance
> tests, a penalty in rolling resistance on "average" roads. I do a two-
> second cost/benefit analysis before each ride, and choose my machine
> accordingly. It is often determined by which set of cleats I can find
> in my closet first....
>
> > > So let's give tire size recommendations by rider weight.
>
> RE: minimum tire size by rider weight. One reasonable approach to
> this issue is to look for a target tire pressure, say 85psi, that one
> doesn't want to exceed. Determine one's wheel load (including all
> your luggage, your bike, and you, fully clothed) then take a look at
> F. Berto's tire-drop chart (check the archives for various links to
> this chart).
Here http://www.vintagebicyclepress.com/images/TireDrop.pdf is a copy
> Hi, All,
>
> RE: margin of safety. In my opinion, a 42mm tire absolutely provides
> a larger margin of safety than the 28-30mm tires. I use both 42-584
> wheels and 28-622 wheels on my randonneuring machines.
>
> The wider tires span cracks better, they climb the edge of road more
> easily, they are not as easily diverted by train tracks etc, they're
> significantly tougher and less likely to be damaged by road debris,
> glass, or potholes, and they last substantially longer.
>
> When combined with an appropriate geometry, they corner better and
> handle as well. The prices I pay for that margin of safety and all
> the other positive attributes of the wider tire: Acceleration, wheel
> weight, and, according to the Bicycle Quarterly rolling resistance
> tests, a penalty in rolling resistance on "average" roads. I do a two-
> second cost/benefit analysis before each ride, and choose my machine
> accordingly. It is often determined by which set of cleats I can find
> in my closet first....
>
> > > So let's give tire size recommendations by rider weight.
>
> RE: minimum tire size by rider weight. One reasonable approach to
> this issue is to look for a target tire pressure, say 85psi, that one
> doesn't want to exceed. Determine one's wheel load (including all
> your luggage, your bike, and you, fully clothed) then take a look at
> F. Berto's tire-drop chart (check the archives for various links to
> this chart).
of the BQ tire pressure article, with chart to help you find the size
that will let you maintain that target pressure for a given load weight.
WMdeR
Dec 10, 2009, 3:52:42 PM12/10/09
to randon
Hi, All,
> > > > So let's give tire size recommendations by rider weight.
>
> > RE: minimum tire size by rider weight. One reasonable approach to
> > this issue is to look for a target tire pressure, say 85psi, that one
> > doesn't want to exceed. Determine one's wheel load (including all
> > your luggage, your bike, and you, fully clothed) then take a look at
> > F. Berto's tire-drop chart (check the archives for various links to
> > this chart).
>
> Herehttp://www.vintagebicyclepress.com/images/TireDrop.pdf is a copy
For example, lets say a rider weighs 150lb in riding kit and shoes,
her machine weighs 22lb including luggage, and she carries 8lb of gear
and spares, including full water bottles. Estimating a weight
distribution of 55 rear/45 front for a front-loading machine, we
arrive at a weight distribution of about 45Kg/37Kg rear/front.
Moving into the chart referenced above and considering the rear wheel,
we see that this rider would need 125psi or so in a 20mm tire, 105psi
in a 23mm tire, 85psi in a 25, and around 75psi in a 28mm, and so
forth down to 43psi in a 37mm tire. With less load, the front tire
inflation pressures would be lower. So, given a maximum 85PSI
inflation pressure, she could freely choose any tire 25mm wide or
wider, depending on her purposes, bicycle design, tire availablility,
and preferred compromises in tire performance.
> > > > So let's give tire size recommendations by rider weight.
>
> > RE: minimum tire size by rider weight. One reasonable approach to
> > this issue is to look for a target tire pressure, say 85psi, that one
> > doesn't want to exceed. Determine one's wheel load (including all
> > your luggage, your bike, and you, fully clothed) then take a look at
> > F. Berto's tire-drop chart (check the archives for various links to
> > this chart).
>
> of the BQ tire pressure article, with chart to help you find the size
> that will let you maintain that target pressure for a given load weight.
>
Thanks Steve. I should have provided a link and an example.
> that will let you maintain that target pressure for a given load weight.
>
For example, lets say a rider weighs 150lb in riding kit and shoes,
her machine weighs 22lb including luggage, and she carries 8lb of gear
and spares, including full water bottles. Estimating a weight
distribution of 55 rear/45 front for a front-loading machine, we
arrive at a weight distribution of about 45Kg/37Kg rear/front.
Moving into the chart referenced above and considering the rear wheel,
we see that this rider would need 125psi or so in a 20mm tire, 105psi
in a 23mm tire, 85psi in a 25, and around 75psi in a 28mm, and so
forth down to 43psi in a 37mm tire. With less load, the front tire
inflation pressures would be lower. So, given a maximum 85PSI
inflation pressure, she could freely choose any tire 25mm wide or
wider, depending on her purposes, bicycle design, tire availablility,
and preferred compromises in tire performance.
hughgs
Dec 10, 2009, 4:06:18 PM12/10/09
to randon
While comfort and performance can lead to a lowering of tire pressure you
must also account for the greater likelihood of pinch flats at these lower
pressures. The frequency of pinch flatting will vary for each rider but
it's definitely something to keep in the back or your mind. Nothing worse
than getting a flat that was due to something completely under your
control.
> --
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(302) 530-9335
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Steve Palincsar
Dec 10, 2009, 4:16:18 PM12/10/09
to hughgs, randon
On Thu, 2009-12-10 at 16:06 -0500, hughgs wrote:
>
> While comfort and performance can lead to a lowering of tire pressure you
> must also account for the greater likelihood of pinch flats at these lower
> pressures.
That's a reason to go with wider tires: you can lower the pressure while
>
> While comfort and performance can lead to a lowering of tire pressure you
> must also account for the greater likelihood of pinch flats at these lower
> pressures.
still avoiding the likelihood of pinch flats. That said, I think it's
true that the spectre of pinch flats is greatly overblown.
> The frequency of pinch flatting will vary for each rider but
> it's definitely something to keep in the back or your mind. Nothing worse
> than getting a flat that was due to something completely under your
> control.
surgeries and a year of physical therapy to recover from a flat...
Kole Kantner
Dec 10, 2009, 8:40:21 PM12/10/09
to Steve Palincsar, randon
I can think of things worse than pinch flats, but I get them all the
time running a 700x20 front at 100psi with a 200lb total weight. Well,
not all the time, but a big pothole or rough gravel road is never a
safe bet for me. I'm starting to try 115 or 120psi since these new
tires don't seem to rip out the sidewalls as much as my previous
version did.
--Kole--
--Kole--
Greg Merritt
Dec 10, 2009, 9:41:53 PM12/10/09
to randon
Kole,
Why not try a 700x25 at reasonable pressures? You may be faster, more
comfortable, and reduce the chance of flats.
-Greg, @155lbs, and no reason to go below 700x28 on my distance bike
(a somewhat heavy machine)...
Why not try a 700x25 at reasonable pressures? You may be faster, more
comfortable, and reduce the chance of flats.
-Greg, @155lbs, and no reason to go below 700x28 on my distance bike
(a somewhat heavy machine)...
Joshua Bryant
Dec 10, 2009, 10:19:17 PM12/10/09
to Kole Kantner, Steve Palincsar, randon
This reminds me, back when I used to run 23's or so I would get pinch flats about quarterly or better. This was pre-randonneuring but whilst I was a courier, so I was logging about 50+ miles per day average. Since trading to wider and even wider tires I haven't gotten a pinch since. Wider for me was 700x30, then later 650x36, FWIW. I currently run 650x36 at about 52 psi rear, and 48 psi front. I weigh about 180 and carry about 8 lbs or so max in my handlebar bag. No idea what my bike weighs though, 26 lbs? I'm totally sold on wider tires, the comfort alone is worth it to me. (I'm lucky enough that I don't wear padded gloves and use cotton cloth tape and haven't any hand issues yet)
-Joshua
-Joshua
Envoyée de mon iPhone
I can think of things worse than pinch flats,ttp://reneherse.com/images/DSC_002325.JPG Well, not all the time, but a big pothole or rough gravel road is never a safe bet for me. I'm starting to try 115 or 120psi since these new tires don't seem to rip out the sidewalls as much as my previous version did.
--Kole--
Steve Palincsar wrote:On Thu, 2009-12-10 at 16:06 -0500, hughgs wrote:While comfort and performance can lead to a lowering of tire pressure you must also account for the greater likelihood of pinch flats at these lower pressures.That's a reason to go with wider tires: you can lower the pressure while still avoiding the likelihood of pinch flats. That said, I think it's true that the spectre of pinch flats is greatly overblown.The frequency of pinch flatting will vary for each rider but it's definitely something to keep in the back or your mind. Nothing worse than getting a flat that was due to something completely under your control.I can think of lots worse things than a flat tire. I never needed 3 surgeries and a year of physical therapy to recover from a flat...
--
Kole Kantner
Dec 10, 2009, 10:58:14 PM12/10/09
to Greg Merritt, randon
Greg,
My 1992 Cannondale road bike will only take 700x21 tires in the front
while still supporting full fenders. I have tried 25mm in the back, but
my current full fenders probably only allow 23mm in the back. I am very
careful about what I run over and don't have too many problems even at
80psi. However, I do seem to be getting more pinch flats now that I
sometimes ride closer to others where it is harder to avoid potholes and
road hazards. In years past I would rip out the sidewalls at the rim
long before the tires wore out so I started dropping the pressure
slightly below 90psi. My current $13 Hutchinson Equinox tires don't
seem to have as many problems with sidewall failure and I am raising the
pressure towards the 110psi max rating to see how they last. With
20,000 to 30,000 miles per year my primary concern after safety is
replacement costs. Front tires last around 10,000 miles for me, but
rears, particularly with hard pedaling seem to only get 2,000 to 4,000
miles each.
I have heard about this "comfort" detail, but I'm not familiar with it.
To me comfort will be when I finally get a frame that lets me reach the
drops without stretching excessively, although perhaps that is not
possible for shorter 5' 7" people like me on a 700 wheel bicycle. Since
I am relatively slow at anything besides climbing I am starting to
realize that tires, aerodynamics, or psychology may be areas I need to
experiment with more. For tires I'll have to look at getting a
different frame that can accommodate wider tires, or maybe just get more
expensive narrow tires. I do occasionally use Continental GP4000 tires
and they don't seem to change anything, so maybe it is all
psychological. If I'm not climbing then I'm resting. Maybe I should
lower my cadence to get more power on the flats and downhills. Or maybe
I should try a power meter to get clearer notice of when I'm slacking off.
--Kole--
My 1992 Cannondale road bike will only take 700x21 tires in the front
while still supporting full fenders. I have tried 25mm in the back, but
my current full fenders probably only allow 23mm in the back. I am very
careful about what I run over and don't have too many problems even at
80psi. However, I do seem to be getting more pinch flats now that I
sometimes ride closer to others where it is harder to avoid potholes and
road hazards. In years past I would rip out the sidewalls at the rim
long before the tires wore out so I started dropping the pressure
slightly below 90psi. My current $13 Hutchinson Equinox tires don't
seem to have as many problems with sidewall failure and I am raising the
pressure towards the 110psi max rating to see how they last. With
20,000 to 30,000 miles per year my primary concern after safety is
replacement costs. Front tires last around 10,000 miles for me, but
rears, particularly with hard pedaling seem to only get 2,000 to 4,000
miles each.
I have heard about this "comfort" detail, but I'm not familiar with it.
To me comfort will be when I finally get a frame that lets me reach the
drops without stretching excessively, although perhaps that is not
possible for shorter 5' 7" people like me on a 700 wheel bicycle. Since
I am relatively slow at anything besides climbing I am starting to
realize that tires, aerodynamics, or psychology may be areas I need to
experiment with more. For tires I'll have to look at getting a
different frame that can accommodate wider tires, or maybe just get more
expensive narrow tires. I do occasionally use Continental GP4000 tires
and they don't seem to change anything, so maybe it is all
psychological. If I'm not climbing then I'm resting. Maybe I should
lower my cadence to get more power on the flats and downhills. Or maybe
I should try a power meter to get clearer notice of when I'm slacking off.
--Kole--
Bill Gobie
Dec 10, 2009, 11:46:55 PM12/10/09
to randon subscribers
On Dec 10, 2009, at 12:28 PM, Steve Palincsar wrote:
>
> Here http://www.vintagebicyclepress.com/images/TireDrop.pdf is a copy
> of the BQ tire pressure article, with chart to help you find the size
> that will let you maintain that target pressure for a given load
> weight.
widths not plotted, or if a wheel weight exceeds the chart's maximum:
pressure (psi) = k * wheel load (lbs)
k = 588 / width^2 , width in mm, ^2 means squared
The regression for k is so good I have to believe Berto used this
equation for plotting the chart. I would certainly like to see his
original paper. (Anybody have a copy of Australian Cyclist, March/
April 2004?)
Since I ride some small-wheeled bicycles I have worked out a model
incorporating wheel diameter. It suggests multiplying k by sqrt(622/
D), where D is the wheel diameter. This is a geometric consequence of
the shorter contact patch. The factor for 451 is 1.17, 406 is 1.24,
369 is 1.3. Thus it appears small wheels should be run at higher
pressures, and/or use wider tires. All the 700C-ish sizes are so
similar the correction is not important. Measuring tire drop is
difficult, so I haven't verified these factors experimentally. If
anyone wants to debate this email me directly since small wheels are
irrelevant for most randos.
Bill Gobie
Message has been deleted
Wesley Cheney
Dec 11, 2009, 6:54:06 AM12/11/09
to Jan Heine, Bill Gobie, randon subscribers
Thanks Jan, Bill, and everyone else, for a productive discussion. There's nothing more frustrating for this Clydesdale than to get excited about a great product review, only to find out that it doesn't come in my size...thank you for bringing more detail & depth to this topic.
Wes
*Stupid Hurts*
*Safety First*
Wes
*Stupid Hurts*
*Safety First*
Ingle, Bruce
Dec 11, 2009, 2:31:41 PM12/11/09
to ran...@googlegroups.com
> To me comfort will be when I finally get a frame
> that lets me reach the drops without stretching
> excessively, although perhaps that is not possible
> for shorter 5' 7" people like me on a 700 wheel
> bicycle.
> that lets me reach the drops without stretching
> excessively, although perhaps that is not possible
> for shorter 5' 7" people like me on a 700 wheel
> bicycle.
> Or maybe I should try a power meter
If you have the money for a power meter, spend it on a bike that fits
first. It'll make far more of a difference in your comfort and speed.
If you're on a tight budget and don't have the money for a 650B or
custom frame, get an undersized MTB hardtail (ISO 559) - perhaps 14" or
16" for your height - and build it up with a threadless headset, a rigid
fork with long steerer, the longest seatpost you can find, drop bars,
rim brakes and 32-37mm (1.25-1.5") tires. The smaller wheel size will
avoid toe overlap and the undersized frame will give you the proper
reach to the bars (MTBs have relatively long top tubes to compensate for
flat bars).
I have a similar machine built up for dirt-road rides (18" frame for a
5'11" rider), and I enjoy it a lot. Kent Peterson has a few ISO 559
machines as well, and completed BMB on one in less time than any of my
1200k's.
- Bruce
Ingle, Bruce
Dec 11, 2009, 3:10:51 PM12/11/09
to lj mangin, ran...@googlegroups.com
> You mean like this?
Yes, and you've gone one better by finding a modern frame with long
stays.
- Bruce
Yes, and you've gone one better by finding a modern frame with long
stays.
- Bruce
Donald Perley
Dec 11, 2009, 5:05:49 PM12/11/09
to Kole Kantner, randon
On Thu, Dec 10, 2009 at 10:58 PM, Kole Kantner <kkan...@gmail.com> wrote:
> My 1992 Cannondale road bike
...
> My 1992 Cannondale road bike
> I have heard about this "comfort" detail, but I'm not familiar with it.
> To me comfort will be when I finally get a frame that lets me reach the
> drops without stretching excessively, although perhaps that is not
> possible for shorter 5' 7" people like me on a 700 wheel bicycle.
I always tell friends to look for a good fit first. Get sized, then
> To me comfort will be when I finally get a frame that lets me reach the
> drops without stretching excessively, although perhaps that is not
> possible for shorter 5' 7" people like me on a 700 wheel bicycle.
look in the boring part of the brochure that has all those tube
lengths and angles. From that process, I could see that Cannondale
road bikes have relatively long top tubes and aren't a good match for
me.
Kole Kantner
Dec 12, 2009, 3:17:52 AM12/12/09
to Ingle, Bruce, ran...@googlegroups.com
Bruce,
Thanks for your helpful suggestions. I didn't mean to imply that I
would buy a power meter. A friend of mine has one I might be able to
borrow to try out. I am not into obtaining maximum performance like a
racer, but I do like comparing data, particularly if it gives me helpful
ideas for changing how I ride.
I used a very nice mountain frame with slick tires for 5 years before it
finally cracked. I think that was due to REI putting a 27.0mm seatpost
in a frame designed for 27.2mm, but by that time they did not have
suitable mountain frames available to replace it with so I switched to a
road frame. I was using flat bars on the mountain frame and I now much
prefer drop bars. I think I could put those on a mountain frame,
although aside from the size issue I now prefer all aspects of road
bikes better. In particular the drop bars and caliper brakes seem so
much better than the disc brakes I used to have. The old cantilevers I
had on previous mountain bikes were even more troublesome being very
difficult to adjust and with lots of squealing in most situations.
Switching to caliper brakes was like night and day. Granted, I don't
use brakes much, but it is such a relief to have them just work for
months at a time. It is also great to be able to replace the pads
easily and have them work like new again. Strangely it seems almost
impossible to adjust them so they don't work great. I also like that
there is a much wider selection of affordable easier rolling tires for
700c than 26" mountain rims.
--Kole--
Thanks for your helpful suggestions. I didn't mean to imply that I
would buy a power meter. A friend of mine has one I might be able to
borrow to try out. I am not into obtaining maximum performance like a
racer, but I do like comparing data, particularly if it gives me helpful
ideas for changing how I ride.
I used a very nice mountain frame with slick tires for 5 years before it
finally cracked. I think that was due to REI putting a 27.0mm seatpost
in a frame designed for 27.2mm, but by that time they did not have
suitable mountain frames available to replace it with so I switched to a
road frame. I was using flat bars on the mountain frame and I now much
prefer drop bars. I think I could put those on a mountain frame,
although aside from the size issue I now prefer all aspects of road
bikes better. In particular the drop bars and caliper brakes seem so
much better than the disc brakes I used to have. The old cantilevers I
had on previous mountain bikes were even more troublesome being very
difficult to adjust and with lots of squealing in most situations.
Switching to caliper brakes was like night and day. Granted, I don't
use brakes much, but it is such a relief to have them just work for
months at a time. It is also great to be able to replace the pads
easily and have them work like new again. Strangely it seems almost
impossible to adjust them so they don't work great. I also like that
there is a much wider selection of affordable easier rolling tires for
700c than 26" mountain rims.
--Kole--
Bill Gobie
Dec 12, 2009, 11:33:30 AM12/12/09
to randon subscribers
On Dec 12, 2009, at 12:17 AM, Kole Kantner wrote:
> In particular the drop bars and caliper brakes seem so
> much better than the disc brakes I used to have. The old
> cantilevers I
> had on previous mountain bikes were even more troublesome being very
> difficult to adjust and with lots of squealing in most situations.
> Switching to caliper brakes was like night and day. Granted, I don't
> use brakes much, but it is such a relief to have them just work for
> months at a time. It is also great to be able to replace the pads
> easily and have them work like new again.
Adjusting caliper pads gives me fits, and every time I hear the front
brake make an unusual noise I check whether the pads are rubbing on
the tire. Avid discs are trivial to adjust, rarely noisy, and easy to
replace the pads. When I changed my Bacchetta Aero to 26" from 650C,
I opted for a front disc brake in order to have a reliable, powerful
brake. No worries about a worn rim exploding, either. If I were ever
to buy a conventional upright bike it would have disc brakes.
Bill Gobie
Wesley Cheney
Dec 12, 2009, 12:15:50 PM12/12/09
to Bill Gobie, randon subscribers
Bill Gobie wrote:
Interchange "disc" and "caliper" and I would agree with you.
Adjusting caliper pads gives me fits, and every time I hear the front
brake make an unusual noise I check whether the pads are rubbing on
the tire. Avid discs are trivial to adjust, rarely noisy, and easy to
replace the pads.
Hear, hear, Bill!Interchange "disc" and "caliper" and I would agree with you.
Adjusting caliper pads gives me fits, and every time I hear the front
brake make an unusual noise I check whether the pads are rubbing on
the tire. Avid discs are trivial to adjust, rarely noisy, and easy to
replace the pads.
I've been riding a hardtail, 700c (a.k.a. 29er) for four years now, and only now am I looking at replacing the Avid BB7 mechanical brake rotors. The pads & cables I replace annually. With Schwalbe Big Apple slicks, 29x2.35", I commute on my hardtail mpst days.
The setup for any brake system can be time-consuming. Personally, I loathe Huffy cantilevers with non-threaded brake pads. I have found the setup on mechanical disc brakes to be, on average, equal to that of mechanical rim brakes.
I particularly like to the ease of "trimming" Avid BB7s: dial the pads closer to the disc, and they grab quicker & harder. Or, extend the barrel adjuster for a softer, more progressive stop.
Finally, wheel maintennance is much easier since you don't have to true out every little dip & wobble in the rim, as the rim no longer touches the brakepads. On a long ride, that can mean that riding home with a busted spoke, not calling for a ride home...
Wes
Bill Gobie
Dec 12, 2009, 1:18:24 PM12/12/09
to Wesley Cheney, randon subscribers
On Dec 12, 2009, at 9:15 AM, Wesley Cheney wrote:
Finally, wheel maintennance is much easier since you don't have to true out every little dip & wobble in the rim, as the rim no longer touches the brakepads. On a long ride, that can mean that riding home with a busted spoke, not calling for a ride home...
And the wheels (and your hands when working on the wheels) stay cleaner without aluminum oxide and brake compound mucking everything up. Especially after a wet ride.
Bill Gobie
Kole Kantner
Dec 12, 2009, 10:04:32 PM12/12/09
to Bill Gobie, randon subscribers
Bill,
I have been using ceramic rims for the last year with caliper brakes and
in addition to very little rim wear the wheels are always nice and
clean. The brake pads also last much longer than my first generation
Avid mechanical disc brakes used to. I think the first set of OEM Avid
pads lasted almost 10,000 miles, but after that I never got more than a
few thousand miles out of Avid brand replacement pads and sometimes only
a hundred miles on very wet steep descents. The squealing with wet
rotors was also terrible and I feel that the noise seemed to be
associated with early pad destruction. With ceramic rims and Koolstop
green pads I get at least 10,000 miles per set of pads after the rim
wears a bit smooth. The main drawback to ceramic rims is the relatively
poor brake performance when the rims are soaking wet. The front also
seems to grab a lot at slow speeds when wet. Still it is great to use
the brakes as much as I need to without worrying about wearing out the
pads or rims.
--Kole--
> http://groups.google.com/group/randon/
I have been using ceramic rims for the last year with caliper brakes and
in addition to very little rim wear the wheels are always nice and
clean. The brake pads also last much longer than my first generation
Avid mechanical disc brakes used to. I think the first set of OEM Avid
pads lasted almost 10,000 miles, but after that I never got more than a
few thousand miles out of Avid brand replacement pads and sometimes only
a hundred miles on very wet steep descents. The squealing with wet
rotors was also terrible and I feel that the noise seemed to be
associated with early pad destruction. With ceramic rims and Koolstop
green pads I get at least 10,000 miles per set of pads after the rim
wears a bit smooth. The main drawback to ceramic rims is the relatively
poor brake performance when the rims are soaking wet. The front also
seems to grab a lot at slow speeds when wet. Still it is great to use
the brakes as much as I need to without worrying about wearing out the
pads or rims.
--Kole--
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