Movement of Parts

[Tom Kunich]

Roger just made a comment that should get a complete answer. Somehow he has the idea that properly tightened parts will not move even under severe overload.

I'm afraid that they will. Especially with modern lightweight parts.

Case in point: I have a Campagnolo Super Record compact crank. In low gear riding normally. even up very steep hills it stays right in gear. So the adjustment of the gears are proper. It makes no clicking and no signs of being under adjusted. But up a very steep hill if I pedal hard, the small ring bends and the derailleur shifts from the 32 into the 25. Then tries to shift back up into the 28. You simply cannot make rings that narrow that won't flex. Using a Cinelli XA quill stem with a Cinelli 26.2 handlebar you wouldn't have the problem. There is sufficient mass and surface area to prevent it.

The case under discussion is a superlight aluminum threadless stem hitting a 3" pothole with a square side at about 25 mph caused me to grab onto the bars to keep from being thrown over them and the bars rotated in the stem. Saying that they have to be "properly adjusted seems to completely ignore the fact that the bike had 1500 miles on it under all conditions without slipping. This included hitting many other potholes if not as severely. This pothole was in the shade and the sunlight on the road was very bright so that I didn't see it until the last second. The front plate is basically nothing more than 2 bolts on each side connected by thin strips of aluminum.

The pretense that you can have light weight and unlimited strength certainly makes a very valiant attempt to avoid reality. One of the stupid four made the same attempt to say that it was impossible to put on a disk brake hard enough to throw yourself over the handlebars.

[Tom Kunich]

I should say that normal carbon bars and stems will ALWAYS rotate regardless of carbon paste or grit. I'm sure the our "mechanical engineer" will deny that even to the extent of saying that there was no need for bicycle manufactures to move to integrated bar-stem combos.

[Catrike Rider]

I know people who have been sent flying from trikes due to locking
disc brakes. I set the disk brakes on my Catrike so that they cannot
lock the wheels at speeds over 5 or 6 MPH for that very reason.

[Tom Kunich]

In several of the grand tours they showed riders being thrown over the bars, In one case they said it was caused by a team leader hitting a roadside concrete barrier but there was no damage to the front end. And many pros are now complaining. because of disk fade they are fitting larger disks which compounds the problem. Not to mention loses to dragging pads.

[Frank Krygowski]

On Wednesday, January 25, 2023 at 6:05:50 PM UTC-5, cycl...@gmail.com wrote:
>
> The case under discussion is a superlight aluminum threadless stem hitting a 3" pothole with a square side at about 25 mph caused me to grab onto the bars to keep from being thrown over them and the bars rotated in the stem.

You certainly have lots of mechanical problems!

- Frank Krygowski

[Catrike Rider]

Well, unlike you, Frank, he rides his bikes.

[John B.]

Well, Frankie don't have to ride no bicycles. See, he's got that big,
bad, 'lectric car AND a motorcycle in the garage.
--
Cheers,

John B.

[funkma...@hotmail.com]

On Wednesday, January 25, 2023 at 6:05:50 PM UTC-5, cycl...@gmail.com wrote:
>

> Roger just made a comment that should get a complete answer. Somehow he has the idea that properly tightened parts will not move even under severe overload.

That's not what he wrote.

>
> I'm afraid that they will. Especially with modern lightweight parts.
>
> Case in point: I have a Campagnolo Super Record compact crank. In low gear riding normally. even up very steep hills it stays right in gear. So the adjustment of the gears are proper. It makes no clicking and no signs of being under adjusted. But up a very steep hill if I pedal hard, the small ring bends and the derailleur shifts from the 32 into the 25. Then tries to shift back up into the 28. You simply cannot make rings that narrow that won't flex.

1) you're talking about parts flexing under load, not tightened parts moving under load.
2) You're describing frame flex, not chainring flex.
3) even _if_ a chainring could flex enough to cause alignment problems (which quality parts don't) A flexing chainring can't cause a rear derailleur to shift. The pros are running 11 speed systems and put significantly more power into the pedals than you, they don't have this problem. And yes, they do use compact cranks as well. https://www.cyclingweekly.com/news/racing/vuelta-a-espana/vuelta-riders-go-super-low-gearing-tackle-monster-climb-349615

> Using a Cinelli XA quill stem with a Cinelli 26.2 handlebar you wouldn't have the problem. There is sufficient mass and surface area to prevent it.

ummm....wait...you're claiming that an old-style stem/bar combination prevents chainring flex? HAH!!!! That's as good as andre claiming batteries have torque! Not to mention modern oversized bar/stem combinations have larger _effective_ surface area.

> The case under discussion is a superlight aluminum threadless stem hitting a 3" pothole with a square side at about 25 mph caused me to grab onto the bars to keep from being thrown over them

You didn't already have your hands on the bars?

> and the bars rotated in the stem. Saying that they have to be "properly adjusted seems to completely ignore the fact that the bike had 1500 miles on it under all conditions without slipping.

That's because the fact that the bike had 1500 miles on it under all conditions without slipping isn't really relevant. I've had bars rotate after a hard hit after several thousands of miles.

> This included hitting many other potholes if not as severely. This pothole was in the shade and the sunlight on the road was very bright so that I didn't see it until the last second. The front plate is basically nothing more than 2 bolts on each side connected by thin strips of aluminum.

Which is a fixing mechanism proven to be more than adequate for all types of riding.

>
> The pretense that you can have light weight and unlimited strength certainly makes a very valiant attempt to avoid reality.

that's a pretense you created in your own mind. Noe one here ever stated anything even remotely similar to 'you can have light weight and unlimited strength'. Besides, the subject of the discussion was properly tightened parts moving under load, not strength to weight ratio.

> One of the stupid four made the same attempt to say that it was impossible to put on a disk brake hard enough to throw yourself over the handlebars.

No one here ever stated it was impossible to put on a disk brake hard enough to throw yourself over the handlebars. Besides, the subject of the discussion was properly tightened parts moving under load, not how effective disk brakes function.

[Roger Merriman]

Tom Kunich <cycl...@gmail.com> wrote:
> Roger just made a comment that should get a complete answer. Somehow he
> has the idea that properly tightened parts will not move even under severe overload.

Hitting a pothole or looking below riding up, steep hills is not severe
overload not remotely. In fact within reason (potholes) it’s expected use.

>
> I'm afraid that they will. Especially with modern lightweight parts.
>
> Case in point: I have a Campagnolo Super Record compact crank. In low
> gear riding normally. even up very steep hills it stays right in gear. So
> the adjustment of the gears are proper. It makes no clicking and no signs
> of being under adjusted. But up a very steep hill if I pedal hard, the
> small ring bends and the derailleur shifts from the 32 into the 25. Then
> tries to shift back up into the 28. You simply cannot make rings that
> narrow that won't flex. Using a Cinelli XA quill stem with a Cinelli 26.2
> handlebar you wouldn't have the problem. There is sufficient mass and
> surface area to prevent it.
>

That’s something wrong with your bike, and your set up. That a parts would
twist and gears change isn’t remotely normal, my bikes are more mid range,
but plenty of folks in the club have the cash for carbon and are big
powerful chaps who.

> The case under discussion is a superlight aluminum threadless stem
> hitting a 3" pothole with a square side at about 25 mph caused me to grab
> onto the bars to keep from being thrown over them and the bars rotated in
> the stem. Saying that they have to be "properly adjusted seems to
> completely ignore the fact that the bike had 1500 miles on it under all
> conditions without slipping. This included hitting many other potholes if
> not as severely. This pothole was in the shade and the sunlight on the
> road was very bright so that I didn't see it until the last second. The
> front plate is basically nothing more than 2 bolts on each side connected
> by thin strips of aluminum.
>

You shouldn’t be able to rotate the bars riding the bike, they use same
bolts and stems on gravel bikes which will take far more impacts let alone
MTB which will use same technology though the stems are much shorter.

> The pretense that you can have light weight and unlimited strength
> certainly makes a very valiant attempt to avoid reality. One of the
> stupid four made the same attempt to say that it was impossible to put on
> a disk brake hard enough to throw yourself over the handlebars.
>

Even tricked out uk hill climb bikes which use all sorts of drilled and so
on light weight parts, notoriously brakes that are fairly inefficient at
times.

These come in at 4/6Kg or 9/13lb respectively and you know what they don’t
have skipping gears!

Roger Merriman

[funkma...@hotmail.com]

No, they don't. It has significantly more to do with the competence of the builder than the inherent design qualities.

> I'm sure the our "mechanical engineer" will deny that even to the extent of saying that there was no need for bicycle manufactures to move to integrated bar-stem combos.

I find that unlikely, but any potential failures due to discrete components wasn't the only reason for the integration.

[funkma...@hotmail.com]

On Wednesday, January 25, 2023 at 6:35:21 PM UTC-5, cycl...@gmail.com wrote:
> On Wednesday, January 25, 2023 at 3:22:42 PM UTC-8, Catrike Rider wrote:
> > On Wed, 25 Jan 2023 15:05:48 -0800 (PST), Tom Kunich
> > <cycl...@gmail.com> wrote:
> >
> > >Roger just made a comment that should get a complete answer. Somehow he has the idea that properly tightened parts will not move even under severe overload.
> > >
> > >I'm afraid that they will. Especially with modern lightweight parts.
> > >
> > >Case in point: I have a Campagnolo Super Record compact crank. In low gear riding normally. even up very steep hills it stays right in gear. So the adjustment of the gears are proper. It makes no clicking and no signs of being under adjusted. But up a very steep hill if I pedal hard, the small ring bends and the derailleur shifts from the 32 into the 25. Then tries to shift back up into the 28. You simply cannot make rings that narrow that won't flex. Using a Cinelli XA quill stem with a Cinelli 26.2 handlebar you wouldn't have the problem. There is sufficient mass and surface area to prevent it.
> > >
> > >The case under discussion is a superlight aluminum threadless stem hitting a 3" pothole with a square side at about 25 mph caused me to grab onto the bars to keep from being thrown over them and the bars rotated in the stem. Saying that they have to be "properly adjusted seems to completely ignore the fact that the bike had 1500 miles on it under all conditions without slipping. This included hitting many other potholes if not as severely. This pothole was in the shade and the sunlight on the road was very bright so that I didn't see it until the last second. The front plate is basically nothing more than 2 bolts on each side connected by thin strips of aluminum.
> > >
> > >The pretense that you can have light weight and unlimited strength certainly makes a very valiant attempt to avoid reality. One of the stupid four made the same attempt to say that it was impossible to put on a disk brake hard enough to throw yourself over the handlebars
> > I know people who have been sent flying from trikes due to locking
> > disc brakes. I set the disk brakes on my Catrike so that they cannot
> > lock the wheels at speeds over 5 or 6 MPH for that very reason.
>
> In several of the grand tours they showed riders being thrown over the bars

If that were true, I'm sure those images exist. Please post one with any accompanying commentary that it was due exclusively to disk brakes prematurely locking up.

> In one case they said it was caused by a team leader hitting a roadside concrete barrier but there was no damage to the front end.

Right. I'm sure it isn't possible to hit a concrete barrier hard enough to toss the rider and leave the bike completely ridable.

> And many pros are now complaining. because of disk fade they are fitting larger disks which compounds the problem. Not to mention loses to dragging pads.

Complete bullshit.
1) complaints about disk brakes ceased years ago as riders realized the benefits far outweigh aby risks
2) Disc brake fade would leave less braking power. If they are complaining about less braking power they can't be complaining about being tossed over the bars because of lock-ups.
3) pro-level road bikes are fitting the same size rotors they have been all along - they are standardized by the UCI.
4) Losses in properly set-up disc systems are negligible.

[Tom Kunich]

Frank's idea of a ride is downtown to a cafe and back. And then to criticize real riders.

[Tom Kunich]

Roger, what do you know about these bikes you claim not to skip gears or roll the bars under and extreme load? When I hit that pothole It almost knocked the Continental GP5000 off of the rim. I just got back from a ride and just looked at it an the tread and probably the cord is broken in the tire. Do you intend to pull a Frank and say, "If you know how to ride you wouldn't break things"?

Don't talk about things you don't have personal experience with. This particular bike has almost $4,000 in it. It is steel and has a steel fork and weighs 8.5 kg. The Look KG685 weighed only a kg less and jumped all over the road when you tried to climb with it. I suppose that it did climb faster but I don't want any more injuries from broken carbon fiber.

[funkma...@hotmail.com]

On Thursday, January 26, 2023 at 5:16:20 PM UTC-5, cycl...@gmail.com wrote:
>
> Roger, what do you know about these bikes you claim not to skip gears or roll the bars under and extreme load?

It doesn't happen on a bike that was built by a competent mechanic.

> When I hit that pothole It almost knocked the Continental GP5000 off of the rim. I just got back from a ride and just looked at it an the tread and probably the cord is broken in the tire. Do you intend to pull a Frank and say, "If you know how to ride you wouldn't break things"?
>
> Don't talk about things you don't have personal experience with.

You do that every day.

[Roger Merriman]

Road tires are fairly fragile so sidewall damage isn’t uncommon.

Rotating a bar due to a jolt isn’t remotely normal, far from it, similar
gears should not be skipping under load, bikes half that weight with kit
that is on the expensive and dubious but oh so light, don’t have that
issue, stopping maybe but not the gears.

> Don't talk about things you don't have personal experience with. This
> particular bike has almost $4,000 in it. It is steel and has a steel fork
> and weighs 8.5 kg. The Look KG685 weighed only a kg less and jumped all
> over the road when you tried to climb with it. I suppose that it did
> climb faster but I don't want any more injuries from broken carbon fiber.
>

4K (dollars) isn’t a wildly high end bike, like for like my MTB is that,
and is very much mid end.

The gravel bike I’ve bough most though not all of groupset (Tiagra) and
last year new wheelset as every this stuff adds up.

Some of the folks in the club plus well being london get 10k (pounds) bikes
lapping Richmond Park lovely bits of kit though personally I tend to the
mid end kit that tends to be in the sweet spot of
performance/durability/cost.

Kit no matter how good it is needs to be set up right, this should be taken
as warning that you need to probably have a good look at your bike or get
some else to, I have lost my ability to do number of stuff I could do.
Fortunately I’m comfortably well off plus bike shop within walking
distance.

Roger Merriman

[sms]

On 1/26/2023 3:08 AM, Roger Merriman wrote:

<snip>

> You shouldn’t be able to rotate the bars riding the bike, they use same
> bolts and stems on gravel bikes which will take far more impacts let alone
> MTB which will use same technology though the stems are much shorter.

I've seen bicycles with improperly tightened bolts on the stem allow the
bars to rotate. The key thing is to tighten them properly.

[Frank Krygowski]

On 1/26/2023 4:59 PM, Tom Kunich wrote:
>
> Frank's idea of a ride is downtown to a cafe and back. And then to criticize real riders.

My idea of a ride is averaging more than 10 mph, unless I'm trying to
keep company with someone much weaker than me! Your Strava data
surprised me.

--
- Frank Krygowski

[Frank Krygowski]

On 1/26/2023 5:55 PM, Roger Merriman wrote:
>
> Rotating a bar due to a jolt isn’t remotely normal, far from it, similar
> gears should not be skipping under load, bikes half that weight with kit
> that is on the expensive and dubious but oh so light, don’t have that

> issue...

Exactly!

> Some of the folks in the club plus well being london get 10k (pounds) bikes
> lapping Richmond Park lovely bits of kit though personally I tend to the
> mid end kit that tends to be in the sweet spot of
> performance/durability/cost.

That's very sensible. As I've said before, bicycling innovations are
deep into diminishing returns. Each extra dollar of expense gets less
and less benefit. That can be verified in terms of dollars per gram
reduction, dollars per mph increase, etc.

The overpowering fact is that the great bulk of both weight and
aerodynamic resistance is the rider. For a ~200 pound rider, losing a
pound of bike weight will make no practical difference, nor will
reducing the bike's drag coefficient by 1/2%.

Unless the rider is going head to head against a rival to win a
finishing sprint - and win a nice water bottle!

--
- Frank Krygowski

[Catrike Rider]

Before you comment on someone's strava data, you should make your's
available. Do you ride at all any more?

BTW, riding a few miles at more than 10MPH is not my idea of a ride,
either.

[AMuzi]

On 1/26/2023 6:12 PM, sms wrote:
> On 1/26/2023 3:08 AM, Roger Merriman wrote:
>
> <snip>
>

>> You shouldn’t be able to rotate the bars riding the

>> bike, they use same
>> bolts and stems on gravel bikes which will take far more
>> impacts let alone
>> MTB which will use same technology though the stems are
>> much shorter.
>
> I've seen bicycles with improperly tightened bolts on the
> stem allow the bars to rotate. The key thing is to tighten
> them properly.
>

+1

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[sms]

On 1/26/2023 5:23 PM, AMuzi wrote:
> On 1/26/2023 6:12 PM, sms wrote:
>> On 1/26/2023 3:08 AM, Roger Merriman wrote:
>>
>> <snip>
>>
>>> You shouldn’t be able to rotate the bars riding the
>>> bike, they use same
>>> bolts and stems on gravel bikes which will take far more
>>> impacts let alone
>>> MTB which will use same technology though the stems are
>>> much shorter.
>>
>> I've seen bicycles with improperly tightened bolts on the
>> stem allow the bars to rotate. The key thing is to tighten
>> them properly.
>>
>
> +1

And BTW, while I greatly prefer Torx over Allen, or external hex, I
don't recall seeing any use of Torx head bolts for handlebar stems. You
just don't need the kind of torque that is possibly with Torx.

[AMuzi]

On 1/26/2023 8:03 PM, sms wrote:
> On 1/26/2023 5:23 PM, AMuzi wrote:
>> On 1/26/2023 6:12 PM, sms wrote:
>>> On 1/26/2023 3:08 AM, Roger Merriman wrote:
>>>
>>> <snip>
>>>

>>>> You shouldn’t be able to rotate the bars riding the

>>>> bike, they use same
>>>> bolts and stems on gravel bikes which will take far more
>>>> impacts let alone
>>>> MTB which will use same technology though the stems are
>>>> much shorter.
>>>
>>> I've seen bicycles with improperly tightened bolts on the
>>> stem allow the bars to rotate. The key thing is to tighten
>>> them properly.
>>>
>>
>> +1
>
> And BTW, while I greatly prefer Torx over Allen, or external
> hex, I don't recall seeing any use of Torx head bolts for
> handlebar stems. You just don't need the kind of torque that
> is possibly with Torx.
>

Once bicycle manufacturers lean on component manufacturers
for the latest round of weight reduction - or else - you'll
see aluminum bolts with Torx.

Allen is perfectly adequate for steel fasteners.

[Jeff Liebermann]

On Thu, 26 Jan 2023 18:03:52 -0800, sms <scharf...@geemail.com>
wrote:

>And BTW, while I greatly prefer Torx over Allen, or external hex, I
>don't recall seeing any use of Torx head bolts for handlebar stems. You
>just don't need the kind of torque that is possibly with Torx.

Earlier today, I repaired a DeWalt DCB115 battery charger:
<https://www.dewalt.com/product/dcb115/12v-max-20v-max-lithium-ion-battery-charger>
The plastic case is held together with four T15 Torx security screws
(with the pin in the middle). I went to the local auto parts store to
buy a Torx security wrench set so I could take the charger apart. I
am not thrilled.
--
Jeff Liebermann je...@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

[Frank Krygowski]

On 1/26/2023 11:49 PM, Jeff Liebermann wrote:
> On Thu, 26 Jan 2023 18:03:52 -0800, sms <scharf...@geemail.com>
> wrote:
>
>> And BTW, while I greatly prefer Torx over Allen, or external hex, I
>> don't recall seeing any use of Torx head bolts for handlebar stems. You
>> just don't need the kind of torque that is possibly with Torx.
>
> Earlier today, I repaired a DeWalt DCB115 battery charger:
> <https://www.dewalt.com/product/dcb115/12v-max-20v-max-lithium-ion-battery-charger>
> The plastic case is held together with four T15 Torx security screws
> (with the pin in the middle). I went to the local auto parts store to
> buy a Torx security wrench set so I could take the charger apart. I
> am not thrilled.

The last time I had that problem, I took an extra Torx bit, annealed it
and drilled a center hole. It was imperfect but it got the job done.

--
- Frank Krygowski

[Jeff Liebermann]

Good idea but it wouldn't have worked for this battery charger. Two
of the four Torx screws were located at the bottom of deep holes. I
could drop a Torx driver bit (1/4" hex) into the hole, but all of my
driver tools were too wide to fit in the hole. I was about to braze a
long hex head bolt to the T15 tip, but decided that buying a thin Torx
set was easier.

I have several of these, which includes nine Torx security bits:
<https://www.acehardware.com/departments/tools/power-tool-accessories/screwdriver-bits/2106060>
However, because of the small hole diameter in the charger, the
included magnetic bit holder was useless.

The set I fished out of the bargain bin at the auto parts store looked
like a smaller version of this:
<https://www.amazon.com/SATA-Tamperproof-Precision-Formed-Chamfered-Impact-Resistant/dp/B07V1JWFFX/>
The hole for the center pin varied considerably between Torx sizes.

I just ordered a set of long Torx driver bits:
<https://www.ebay.com/itm/165368238721>
Cheap.

[Frank Krygowski]

On 1/27/2023 1:09 PM, Jeff Liebermann wrote:
> On Fri, 27 Jan 2023 11:11:48 -0500, Frank Krygowski
> <frkr...@sbcglobal.net> wrote:
>
>> On 1/26/2023 11:49 PM, Jeff Liebermann wrote:
>>> On Thu, 26 Jan 2023 18:03:52 -0800, sms <scharf...@geemail.com>
>>> wrote:
>>>
>>>> And BTW, while I greatly prefer Torx over Allen, or external hex, I
>>>> don't recall seeing any use of Torx head bolts for handlebar stems. You
>>>> just don't need the kind of torque that is possibly with Torx.
>>>
>>> Earlier today, I repaired a DeWalt DCB115 battery charger:
>>> <https://www.dewalt.com/product/dcb115/12v-max-20v-max-lithium-ion-battery-charger>
>>> The plastic case is held together with four T15 Torx security screws
>>> (with the pin in the middle). I went to the local auto parts store to
>>> buy a Torx security wrench set so I could take the charger apart. I
>>> am not thrilled.
>
>> The last time I had that problem, I took an extra Torx bit, annealed it
>> and drilled a center hole. It was imperfect but it got the job done.
>
> Good idea but it wouldn't have worked for this battery charger. Two
> of the four Torx screws were located at the bottom of deep holes. I
> could drop a Torx driver bit (1/4" hex) into the hole, but all of my
> driver tools were too wide to fit in the hole. I was about to braze a
> long hex head bolt to the T15 tip, but decided that buying a thin Torx
> set was easier.

I understand. There was a time when, having little money, I often looked
at various gizmos and said "Hah. No need to spend money, I can make that
thing." Nowadays, I'm much more likely to say "It's only $___. I can
afford that."

I do make exceptions for time spent. That is, if I want the job done
faster than doing a trip to the store and back, or waiting for delivery,
etc. I'll do things myself, including making gizmos.

--
- Frank Krygowski

[sms]

On 1/26/2023 8:49 PM, Jeff Liebermann wrote:
> On Thu, 26 Jan 2023 18:03:52 -0800, sms <scharf...@geemail.com>
> wrote:
>
>> And BTW, while I greatly prefer Torx over Allen, or external hex, I
>> don't recall seeing any use of Torx head bolts for handlebar stems. You
>> just don't need the kind of torque that is possibly with Torx.
>
> Earlier today, I repaired a DeWalt DCB115 battery charger:
> <https://www.dewalt.com/product/dcb115/12v-max-20v-max-lithium-ion-battery-charger>
> The plastic case is held together with four T15 Torx security screws
> (with the pin in the middle). I went to the local auto parts store to
> buy a Torx security wrench set so I could take the charger apart. I
> am not thrilled.

Time for a trip over the hill to Harbor Freight Tools:
<https://www.harborfreight.com/security-bit-set-33-piece-68459.html>.

[Joerg]

On 1/25/23 3:05 PM, Tom Kunich wrote:
> Roger just made a comment that should get a complete answer. Somehow he has the idea that properly tightened parts will not move even under severe overload.
>

> I'm afraid that they will. Especially with modern lightweight parts.
>
> Case in point: I have a Campagnolo Super Record compact crank. In low gear riding normally. even up very steep hills it stays right in gear. So the adjustment of the gears are proper. It makes no clicking and no signs of being under adjusted. But up a very steep hill if I pedal hard, the small ring bends and the derailleur shifts from the 32 into the 25. Then tries to shift back up into the 28. You simply cannot make rings that narrow that won't flex. Using a Cinelli XA quill stem with a Cinelli 26.2 handlebar you wouldn't have the problem. There is sufficient mass and surface area to prevent it.

Bike stuff isn't as sturdy as car stuff :-(

>
> The case under discussion is a superlight aluminum threadless stem hitting a 3" pothole with a square side at about 25 mph caused me to grab onto the bars to keep from being thrown over them and the bars rotated in the stem. Saying that they have to be "properly adjusted seems to completely ignore the fact that the bike had 1500 miles on it under all conditions without slipping. This included hitting many other potholes if not as severely. This pothole was in the shade and the sunlight on the road was very bright so that I didn't see it until the last second. The front plate is basically nothing more than 2 bolts on each side connected by thin strips of aluminum.
>

The only way the stem on my MTB holds reasonably well is if I overtorque
the hex bolt a bit _and_ put regular grid toothpaste on the surface.
Must be regular paste, not the gel version for electric toothbrushes.

> The pretense that you can have light weight and unlimited strength certainly makes a very valiant attempt to avoid reality. One of the stupid four made the same attempt to say that it was impossible to put on a disk brake hard enough to throw yourself over the handlebars.
>

If you have a serious front brake like mine with an 8" rotor that's no
problem. I can make the rear come off the ground with it even when the
panniers and the trunk/platform are heavily loaded:

https://www.analogconsultants.com/ng/bike/Muddy5.JPG

So catapulting me over the bars would be easy but, of course, I have so
far avoided that when braking. Hitting a ditch, rut, root or rock the
outcome can be different (and has been).

--
Regards, Joerg

http://www.analogconsultants.com/

[Jeff Liebermann]

On Fri, 27 Jan 2023 12:38:37 -0800, sms <scharf...@geemail.com>
wrote:

The Harbor Fright store in Watsonville is closer:
<https://www.harborfreight.com/storelocator/1060-s-green-valley-road-watsonville-95076?number=875>

I mentioned in a later posting that I have several identical bit sets:
<https://www.acehardware.com/departments/tools/power-tool-accessories/screwdriver-bits/2106060>
which I mostly purchased at the local hardware store. I consider them
disposable because someone is always "borrowing" the set. I also
mentioned why I didn't use any of the bits. Two of the four Torx
fasteners were at the bottom of holes which were too narrow to fit any
of the magnetic driver tools I had available.

[Tom Kunich]

But Joerg, you've seen here that properly installed parts to manufacturers specification according to the people who do not ride, will not slip nor break. A man who appears to ride MTB's a lot is willing to tell me that I don't climb on the road enough with only a mere 4,000 miles per year and 145,000 feet of climbing in the last year. Well, he is welcome tro have his own rules of thumb, but trying to press them on others is hardly correct. I would bet that he climbs nowhere near as much as you and that you wouldn't criticize his riding because it wasn't the same as yours.

[Frank Krygowski]

On 1/27/2023 6:01 PM, Tom Kunich wrote:
>
> But Joerg, you've seen here that properly installed parts to manufacturers specification according to the people who do not ride, will not slip nor break.

My bars did not slip on the 4000 mile coast to coast tour we did. I
think that counts as riding.

--
- Frank Krygowski

[Catrike Rider]

When was that?

[Roger Merriman]

My bars have not slipped even on my old bike which is 17 years old has a
older two bolt clamp, has done fairly huge mileage is rather my grandfather
axe/broom in that only the frame bars stem and seat post are original.

Due to it’s weight and torque effects (i assume) it does go though QR
(front wheel) in that they will start to slowly slip.

Roger Merriman

[funkma...@hotmail.com]

On Friday, January 27, 2023 at 3:54:54 PM UTC-5, Joerg wrote:
> On 1/25/23 3:05 PM, Tom Kunich wrote:
> > Roger just made a comment that should get a complete answer. Somehow he has the idea that properly tightened parts will not move even under severe overload.
> >
> > I'm afraid that they will. Especially with modern lightweight parts.
> >
> > Case in point: I have a Campagnolo Super Record compact crank. In low gear riding normally. even up very steep hills it stays right in gear. So the adjustment of the gears are proper. It makes no clicking and no signs of being under adjusted. But up a very steep hill if I pedal hard, the small ring bends and the derailleur shifts from the 32 into the 25. Then tries to shift back up into the 28. You simply cannot make rings that narrow that won't flex. Using a Cinelli XA quill stem with a Cinelli 26.2 handlebar you wouldn't have the problem. There is sufficient mass and surface area to prevent it.
> Bike stuff isn't as sturdy as car stuff :-(

The obvious point here is that tommy was first talking about "properly tightened" parts moving under load, then attempts to use an example of flexing chainrings as a "case in point".

[Frank Krygowski]

Is that a disc brake bike?

As discussed intensely here in years past, disc brakes and rim brakes
apply much different forces at the dropout-axle interface.

My bikes all have rim brakes. The only problem I've had with quick
releases is failing to annually lubricate their internals. They still
work; they're just more difficult to clamp until I re-lube.

--
- Frank Krygowski

[Roger Merriman]

Yup old MTB, since MTB have been on disk for well decades.

I think it’s the wear of the cam within the lever, the bike can be quite
heavy as well it’s my commute bike now so I carry stuff there and back and
so on, and some of that weight is via the bar bag as I find keeping the
weight balanced keeps the bike feeling lively, even if it’s fully loaded!

Roger Merriman

[Tom Kunich]

You've got that now from Frank, the expert rider. The bars on his fat tired touring bike didn't slip so obviously a road bike cannot possibly slip. Every time he posts the abject ignorance shows through like a bright sun breaking through clouds.

[Tom Kunich]

Roger, you certainly haven't shown any real understanding of road bikes. See if you can convince Joerg who commutes on gravel to work. I really want to see a flat bar on a bike with front suspension. slip.

[Jeff Liebermann]

On Sat, 28 Jan 2023 11:39:19 -0800 (PST), Tom Kunich
<cycl...@gmail.com> wrote:

> The bars on his fat tired touring bike didn't slip so obviously a road bike cannot possibly slip.

This might offer a clue. Many years ago, the bars on my Miyata 610, a
touring bike, were slipping rather often.
<http://www.learnbydestroying.com/jeffl/pics/bicycles/#img=Miyata-610.JPG>
I kept adjusting and cleaning the clamping area on the bars, but they
kept slipping. One day, I removed the bar tape, brake levers, and
contraptions attached to the handlebars for cleaning. Inside the
clamping area on the stem, was a layer of fine sand. There was no
sand on the handlebars. Under the microscope, the grains looked
almost spherical. I have no idea where the sand came from (possibly a
sand/vapor blaster), but cleaning it off the stem with fine sandpaper
solved the handlebar slippage problem.

[Roger Merriman]

My commute i cover roads, cycleways, park paths, raised decking (think
north shore and you’ll be close) grass paths and so on.

None of my bikes have ever the bars slip, seat post bolt maybe and even
then hardly dramatically but over months generally. It’s a route that
favours bikes with big tires and a rider with MTB experience, doable on a
Gravel bike though you need to be touch more careful in some places, road
bike in the summer maybe though that would fall into just because you can
doesn’t mean you should!

The old MTB no longer has a suspension fork, as I really didn’t need it,
and it just tended to get killed by the weather. It’s a fairly rattling
route although pleasant view’s considering the area ie Heathrow.

Bars rotating isn’t a failure method I’ve come across and I’ve been into
road cycling and clubs for quite some time, folks do daft stuff, they
forget to charge stuff, over extended seat post that snap, rip sidewalls,
have tubless failures, and so on!

Roger Merriman

[Frank Krygowski]

On 1/28/2023 2:39 PM, Tom Kunich wrote:
>
> You've got that now from Frank, the expert rider. The bars on his fat tired touring bike didn't slip so obviously a road bike cannot possibly slip.

Hmm. "Fat tire?" That bike has run everything from 25s to 37s. Most
typical have been 28s. Yet my bars have never slipped.

I've _never_ said a road bike's handlebars cannot possibly slip. They
certainly can, when installed by an incompetent mechanic.

--
- Frank Krygowski

[Tom Kunich]

If you think that 25.4" threadless bars don't slip perhaps you'd like to explain why they went to 28.2, 31.8mm and then 35.4?` Perhaps you can tell the racing mechanics that they have no idea of how to set up bikes?

I am not trying to insult you but to get you to realize that you RIDE much differently and in far different conditions than I do. Even without a suspension fork a 3 1/2" tire offers a very large amount of suspension. Much greater than a 28 mm dropping into a 3" deep pothole.

[Roger Merriman]

I’d assume stiffness, I certainly on my first road bike, which was old
steel bike the bars would flex under load mainly due to the fairly silly
gearing it had! Ie high torque values.

But bars didn’t rotate they flexed yes on steep hills if out of the saddle.

> I am not trying to insult you but to get you to realize that you RIDE
> much differently and in far different conditions than I do. Even without
> a suspension fork a 3 1/2" tire offers a very large amount of suspension.
> Much greater than a 28 mm dropping into a 3" deep pothole.
>

That same bike had 20mm tires though being steel and probably low end had
some give and did feel planted this said it wasn’t a bike that liked to
change direction mid corner or at all really want it wanted to do was go
straight. But it was a likeable machine!

And after that had number of bikes mostly with 25mm tires one was a track
bike so sharp geometry and no give or compliance at all! Lovely on smooth
tarmac bit of handful if not!

Roger Merriman

[sms]

The increase in clamp diameter was also due to the use of aluminum
handlebars instead of steel. Never seen 35.4 but perhaps, if they do
exist, it's for carbon fiber. As you use weaker and weaker materials you
want more surface area for the clamp.

[Frank Krygowski]

On Saturday, January 28, 2023 at 7:20:38 PM UTC-5, cycl...@gmail.com wrote:
>
> If you think that 25.4" threadless bars don't slip perhaps you'd like to explain why they went to 28.2, 31.8mm and then 35.4?` Perhaps you can tell the racing mechanics that they have no idea of how to set up bikes?

The all can slip if installed incompetently.

But as to why they increased diameter - um, after ~100 years of standard diameters ...
the motivation was probably the same as for larger diameter frame tubes. If other things
are kept equal and if buckling isn't a hazard from extremely thin walls, increasing a tube's
diameter increases its strength and stiffness, and/or reduces its weight. I assume
improved manufacturing technology, probably from hydroforming, made the new bar
designs feasible.

- Frank Krygowski

[Roger Merriman]

35mm is what MTB bars are heading towards apparently at moment have 31.8
and 35mm

Roger Merriman

[funkma...@hotmail.com]

You're partially correct Roger, It was a way to decrease weight and add stiffness at the same time. It wasn't because 25.4 were any more prone to slippage.

[AMuzi]

On 1/28/2023 6:20 PM, Tom Kunich wrote:
> On Saturday, January 28, 2023 at 12:19:41 PM UTC-8, Roger Merriman wrote:
>> Tom Kunich <cycl...@gmail.com> wrote:
>>> On Saturday, January 28, 2023 at 3:16:45 AM UTC-8, Roger Merriman wrote:
>>>> Frank Krygowski <frkr...@sbcglobal.net> wrote:
>>>>> On 1/27/2023 6:01 PM, Tom Kunich wrote:
>>>>>>
>>>>>> But Joerg, you've seen here that properly installed parts to
>>>>>> manufacturers specification according to the people who do not ride,
>>>>>> will not slip nor break.
>>>>>
>>>>> My bars did not slip on the 4000 mile coast to coast tour we did. I
>>>>> think that counts as riding.
>>>>>
>>>> My bars have not slipped even on my old bike which is 17 years old has a
>>>> older two bolt clamp, has done fairly huge mileage is rather my grandfather
>>>> axe/broom in that only the frame bars stem and seat post are original.
>>>>

>>>> Due to it’s weight and torque effects (i assume) it does go though QR

>>>> (front wheel) in that they will start to slowly slip.
>>>>
>>>> Roger Merriman
>>>
>>> Roger, you certainly haven't shown any real understanding of road bikes.
>>> See if you can convince Joerg who commutes on gravel to work. I really
>>> want to see a flat bar on a bike with front suspension. slip.
>>>
>> My commute i cover roads, cycleways, park paths, raised decking (think

>> north shore and you’ll be close) grass paths and so on.

>>
>> None of my bikes have ever the bars slip, seat post bolt maybe and even

>> then hardly dramatically but over months generally. It’s a route that

>> favours bikes with big tires and a rider with MTB experience, doable on a
>> Gravel bike though you need to be touch more careful in some places, road
>> bike in the summer maybe though that would fall into just because you can

>> doesn’t mean you should!
>>
>> The old MTB no longer has a suspension fork, as I really didn’t need it,
>> and it just tended to get killed by the weather. It’s a fairly rattling
>> route although pleasant view’s considering the area ie Heathrow.
>>
>> Bars rotating isn’t a failure method I’ve come across and I’ve been into

>> road cycling and clubs for quite some time, folks do daft stuff, they
>> forget to charge stuff, over extended seat post that snap, rip sidewalls,
>> have tubless failures, and so on!
>>
>> Roger Merriman
>
> If you think that 25.4" threadless bars don't slip perhaps you'd like to explain why they went to 28.2, 31.8mm and then 35.4?` Perhaps you can tell the racing mechanics that they have no idea of how to set up bikes?
>
> I am not trying to insult you but to get you to realize that you RIDE much differently and in far different conditions than I do. Even without a suspension fork a 3 1/2" tire offers a very large amount of suspension. Much greater than a 28 mm dropping into a 3" deep pothole.
>

Diameter is not critical.

Keirin bars are 25.4mm and those guys are all muscle with
lots of torque (more than you or I):
http://www.trbimg.com/img-50135d11/turbine/mc-mc-cycling-keirin-cup-07272a.jpg-20120727/600

Their bars do not slip.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[Tom Kunich]

Flat bars are hardly going to rotate so why are they increasing the diameter of the stems and bars

https://thelostco.com/products/renthal-apex-35

After all, properly installed they should not break nor move.

https://www.ebay.com/itm/185717240337?hash=item2b3d9c3211:g:AFEAAOSwYHFjrgaI&amdata=enc%3AAQAHAAAAoBp54iQMKeV1p2vE3ddSapJutcWKGP5b1UtePs34ubyngBVDb3P9dNlhVJuO1rF0d%2BVZKp%2BrXDZEq1D%2FxyCNOrW9GKrfjK4OHL9oYbhzfuR1T1Iy8jkNVP2zSxbISLg%2BkC29ZiSRUrVBWMaTSlpUq2m1HaNPuqH2nR%2BqaHmIMCyH6VBe9DbtEWoPE5V66Tfnyr2ztGyhVKCXARRVyqz5pt0%3D%7Ctkp%3ABk9SR5jK8ua_YQ

Surely this couldn't be because smaller diameter moves? After all - this is an ALLOY bar and that superb mechanical engineer, Krygowski, tells us that since HIS touring bike bars didn't move in a coast to coast ride that no high performance bike and rider should have the slightest problem.

[Tom Kunich]

So you're saying that Keirin riders ride over pot holes and broken roads? Really Andrew, I'm very surprised that you would use that as an example.