Randonneur vs compact road geometry

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Nick Merrell

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Dec 25, 2020, 12:26:48 AM12/25/20
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If you're used to bikes with compact road geometry, how do you find a good fit on a low-trail randonneur frame? Is it typical to pick a frame with a longer top tube? A good example of this would be Jan's PBP bike here:

When we see Jan ride certain other bikes, we see him take a much lower position, like how he rides his Firefly here: https://www.renehersecycles.com/wp-content/uploads/2016/09/assembled.jpg?w=640

Cary Weitzman

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Dec 25, 2020, 11:34:02 AM12/25/20
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December 25, 2020 at 12:26 AM
If you're used to bikes with compact road geometry, how do you find a good fit on a low-trail randonneur frame? Is it typical to pick a frame with a longer top tube?
Fit doesn't change just because the top tube on a bike is level or not. So if you have a bike with compact geo that you like the fit on, starting with that same fit on a randonneuse would be the way to proceed.

The only gotcha is ensuring there's enough standover clearance on the bike with a level top tube.

Personally, I like the bars a little higher and my knees further behind the pedal on a rando compared to a racing bike. More of a touring position instead of a racing position, but that's just me.

Jan's saddle to bar height positioning is Jan's own choice and does not represent an "ideal" position on a rando bike. It's his own personal fit and what works for him.

Bikeinsights.com is a great site to visualize this stuff on. The Crust Canti Lightning bolt, the Box Dog Pelican and the Ocean Air Rambler are all available as examples of clasic style rando bike to compare against.

Cary
PTBO.ON.CA

Brad

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Dec 25, 2020, 11:44:31 AM12/25/20
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I would agree with a caveat.
At some point the back of the stem will jab you in the belly when you step off the saddle.
Similarly if you use bar end shifters, the shifters can bang into your legs at inopportune times while off the saddle. 
Having done a conversion on a compact frame, then one on an earlier longer top tubed frame, I prefer the more classic French style.  At some outer fringe of design, the compact frame is derived from the Orange Krate of yore.

Ken Freeman

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Dec 25, 2020, 4:21:32 PM12/25/20
to Cary Weitzman, 650b
And remember, Jan spent significant time in competitive road racing before starting VBQ.
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Ken Freeman

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Dec 25, 2020, 4:24:35 PM12/25/20
to Brad, 650b
OMG, hence my persistent impression that these do not look like grownups’ bikes!!
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J L

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Dec 25, 2020, 6:27:01 PM12/25/20
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Nick,

To show there is no right way I will respectfully disagree with an earlier poster. Rather than being ensuring there is enough stand over clearance my view is that one should challenge their perception of how much stand over clearance is necessary. I have ridden tons of miles on bikes with negative standover. Don’t look for the frame measurements to match your current bikes because the french style randonneur bikes are different in enough ways that they wont match.

At the end of the day any well fitting bike will work on a brevet, or a long ride. Imagine the french style randonneur as a bike where one is meant to ride at a steady pace for long distance. The frame geometry reflects this, here are just a few ways it is usually different than a compact style road frame.

The seat tube may be longer because the BB is lower.
The seat tube may be longer so the top of the headset is also higher, so the stem doesn't need much additional vertical height to get the bars up at a good height relative to the seat. This helps for long distance comfort and efficiency.
The top tube is longer to help prevent toe clip overlap with the front wheel - typically fenders are installed so the space behind the wheel extends toward the rotating pedals by an extra 25mm or so.
The top tube is longer because the best place to mount a front bag is on a rack that is low above the fendered wheel and close to the head tube - too long of a stem creates are real annoyance when mounting and using a handlebar bag.

What I mean to say is, yes the top tube might be proportionally longer than on the bikes you are familiar with but your contact points should remain about the same. Expect that a shorter stem and seatpost will be used to arrive at your desired touch point measurements. 20mm less? That is just a guess.

There are many ways to setup a randonneur bicycle but these notes explain some of why the bike you referenced is set up as it is.

Cheers
Jason in CA



David Parsons

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Dec 26, 2020, 12:41:39 AM12/26/20
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Pick the frame that's most comfortable for you.  If prefer compact road geometry, try out compact road geometry with a low trail fork (admittedly this is easier if you can build your own forks, but I used a fork with a longer a-c & a conduit bender when I low-trailed my Soma Speedster about 10 years back) before tweaking the rest of the geometry of the bike.

-david parsons

satanas

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Dec 26, 2020, 9:25:14 AM12/26/20
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My problem here is with the word "versus" - good fit is good fit, no matter what type of bike it is. Everything else is style/convention. BQ and others have pushed the idea that to ride long distances one must ride a relatively large frame ("French Fit") but this is just not true. Neither is it necessary to have low trail, unless you like that sort of handling, and not everyone does.

As long as the bars and saddle can be sited appropriately for the rider - and this will vary due to flexibility, core strength, fitness, age, etc - then the frame fits adequately. There are other factors like TCO (if this bothers you), provision for load carrying (if you want to use certain types of bags), and so on and so forth.

To generalise, one might normally expect a rando bike to have a slightly longer front centre (to minimise or eliminate TCO and/or allow room for fenders), and slightly longer chainstays to allow for fenders and tyre clearance, but if 650b wheels are used this will take care of some of this. Level top tubes are mainly about traditional style and are not functionally superior IMHO.

The important thing is that the bike fits its rider and handles "properly" - which will vary with personal preference. Everything thing else can be varied significantly, and appearance really doesn't matter as long as things work.

Later,
Stephen (who dislikes French Fit, low trail *and* large handlebar bags)

Steve Palincsar

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Dec 26, 2020, 9:56:15 AM12/26/20
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Although our preferences for frame style, load carrying and trail are
poles apart about all I can disagree with in your post is the comment
that BQ has promoted "French fit" as necessary to ride long distances. 
That's just plain wrong, and I defy you to cite an example where this is
said.  Go ahead, I have a copy of every issue ready to hand.

Aside from that misconception, I think it's possible to expand a little
on the notion of "proper" handling for long distance riding.  Handling
that's optimum for criterium racing -- frequent turns, highly sensitive
and reactive to the slightest twitch -- is far from optimum for a riding
discipline where turns are far less frequent, groups of drafting riders
are much smaller, and riders will have significant fatigue.


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Stephen Poole

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Dec 26, 2020, 10:54:57 AM12/26/20
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Jan and the other members of the BQ "squad" all appear to have frames that I would say fall into the FF style. It's also quite noticeable that these bikes are the ones that consistently get the nod, whereas anything more modern in style or with non-RH-distributed components rarely gets a positive review, Gerard Vroomen designed bikes (Open & 3T) excepted.

When one consistently promotes traditional FF frames as the ne plus ultra it's not necessary to say in so many words: "This is what you must have" - the inference is obvious, and the fact that it's taken as such is IMO obvious from many/most of the discussions here.

Later,
Stephen

Ray Varella

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Dec 26, 2020, 11:54:43 AM12/26/20
to Stephen Poole, 650b
Being one who has ridden bikes that were more biased towards classic stage race geometry, I’ve never ridden a bike with more modern geometry. 
Setback is always my priority and from there I want to be able to get my bars at a comfortable distance and height. 
Being a shorter rider, most production frames have steeper seat tube angles than I prefer and while there are seatposts that offer more setback, that doesn’t always address other comfort issues. 

Seat tube angles which are too steep have me pushing against my bars to keep my position on the saddle. 
Too shallow angles seem to affect my hip flexors, not in the same way that longer cranks do but it’s noticeable on longer rides. 

If I were ever to design my own frame, I would be starting with my seated position.  

Can anyone offer some insight into whether this thinking is flawed?

Ray


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John P

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Dec 26, 2020, 2:03:24 PM12/26/20
to Stephen Poole, 650b
You think the Firefly falls into the FF style? How is it that
different from a Vroomen design? Jan seems to go on about how much he
likes that bike.
-John

Stephen Poole

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Dec 26, 2020, 6:55:50 PM12/26/20
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No, that's the exception, but everything steel Jan likes seems to be FF...

Benz Ouyang

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Dec 26, 2020, 7:41:31 PM12/26/20
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On Saturday, December 26, 2020 at 7:54:57 AM UTC-8 satanas wrote:
Jan and the other members of the BQ "squad" all appear to have frames that I would say fall into the FF style. It's also quite noticeable that these bikes are the ones that consistently get the nod, whereas anything more modern in style or with non-RH-distributed components rarely gets a positive review, Gerard Vroomen designed bikes (Open & 3T) excepted.

Your comment prompted me to suddenly remember the debacle years ago when BQ reviewed a Pegoretti Love #3. The fact that it was set up as a French fit caused fits amongst The Velominati, and lessened the main messages and questions from the review.

Steve Palincsar

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Dec 27, 2020, 9:27:20 AM12/27/20
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On Saturday, December 26, 2020 at 7:54:57 AM UTC-8 satanas wrote:
Jan and the other members of the BQ "squad" all appear to have frames that I would say fall into the FF style. It's also quite noticeable that these bikes are the ones that consistently get the nod, whereas anything more modern in style or with non-RH-distributed components rarely gets a positive review, Gerard Vroomen designed bikes (Open & 3T) excepted.



And yet, "more modern in style" bikes are frequently showcased on the RH and BQ Instagrams.  Also, lest one forget, Jan thought the world of the Specialized Diverge.

I think your view of JH, RH and BQ is deeply slanted by your preconceptions.

Benz Ouyang

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Dec 27, 2020, 12:17:04 PM12/27/20
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On Sunday, December 27, 2020 at 6:27:20 AM UTC-8 Steve Palincsar wrote:
On Saturday, December 26, 2020 at 7:54:57 AM UTC-8 satanas wrote:
Jan and the other members of the BQ "squad" all appear to have frames that I would say fall into the FF style. It's also quite noticeable that these bikes are the ones that consistently get the nod, whereas anything more modern in style or with non-RH-distributed components rarely gets a positive review, Gerard Vroomen designed bikes (Open & 3T) excepted.

And yet, "more modern in style" bikes are frequently showcased on the RH and BQ Instagrams.  Also, lest one forget, Jan thought the world of the Specialized Diverge.


We need to be cognizant that BQ is still dependent on manufacturers to provide bikes and equipment for review. French-fit bikes are not really in vogue right now, so unless BQ resigns itself to reviewing predominantly niche custom bikes, it has no choice but to review "modern style" bikes, even if that's not its preferred style (which is suspiciously à la Rene Herse from decades ago).

Steve Palincsar

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Dec 27, 2020, 12:57:28 PM12/27/20
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No, JH absolutely loved some of those Open UPs and the Diverge.

Cary Weitzman

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Dec 27, 2020, 1:23:08 PM12/27/20
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Benz Ouyang wrote:
unless BQ resigns itself to reviewing predominantly niche custom bikes, it has no choice but to review "modern style" bikes, even if that's not its preferred style (which is suspiciously à la Rene Herse from decades ago).

I seems as though every BQer who's test-ridden an UPPER has expressed total lust for the bike, and not that long ago BQ's Instagram teased that the MIND was the fastest bike they've ever tested.

Jan really liked the Checkpoint, silly sliding rear dropouts and all, and he bought the Firefly test bike.

This doesn't sound like people who are unenthusiastic about modern style bikes, whatever their preferences might be.

Cary
PTBO.ON.CA

Murray Love

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Dec 27, 2020, 1:54:04 PM12/27/20
to Ray Varella, Stephen Poole, 650b
With modern long-railed saddles and setback seatposts, seat-tube angle should be mostly a non-factor, except at the extremes (say, greater than 74° or less than 71°). However, if you're riding a Brooks or some other vintage saddle, seat-tube angle becomes quite important due to the limited aft rail travel.

On the OP topic, I agree that there really isn't any material difference between compact frames and level TT frames, as long as you can get 1) the correct saddle position with respect to the cranks, and 2) the right bar position with respect to 1). I prefer the aesthetics of level TT frames, but the ideal is that you shouldn't be able to tell the difference from a fit perspective. There's nothing inherently different about the contact positions.

Murray
Victoria, BC

Ken Freeman

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Dec 27, 2020, 9:11:38 PM12/27/20
to satanas, 650b
I like my butt to be behind the BB to the point where if I am perched on the saddle with my sitbones nicely supported, I like to be able to lift myself off the saddle over bumps, and lift up hands without moving forward or back, just like Steve Hogg advocates, as does American Lennard Zinn.  I don't know if it' my femurs, my fat upper body, my non-Olympic core strength or what, but this means that with a Brooks Prof and vintage Campy seatpost, I would need a seat tube around 71 or 72 degrees angle.  From there I need a designer to help work out rear and front wheel positions, et cetera.  My position and the resulting frame/post/saddle requirement have nothing to do with a French Fit or a Chicago Teenager fit.  The bike can LOOK like a 1935 Herse or a 2005 stage-race bike made of ELOS equipped with a monostrut seatstay.  But for my "good fit" that's the ballpark.  It might end up reminding people of the look of a classic randonneurs or '50 Clubman for extended British time trials, or it may not.  My geometry might match that of some actual vintage Brits, but the styling is something different indeed.

Would you call it a French Fit because of the seat tube, or the long front-center, or what?  Why not just call it Ken's Fit? 

Ken Freeman, Ann Arbor, MI USA

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Ken Freeman

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Dec 27, 2020, 9:24:46 PM12/27/20
to Nick Merrell, 650b
One of the most important things is to set up the seat tube to place your butt where it needs to be.  This is not based on "compact," "traditional," or "randonneuse." it's based on, what is the necessary angle of the seat tube? This is based on how your body likes to pedal and how it is efficient at pedaling.    After that is set you can look at "what is the upper limit position for the seat tube?"  Again this has some subjectivity.  How much physical contact can you accommodate when dismounting your bike?  If your builder thinks you need the seat tube to contact the head tube at the top, you can adjust the clearance by angling the TT.  So what?  I don't know if this makes the bike a compact or if its geometry is uniquely yours.  My point is the shape of the bike should emerge from considering the needs of the rider, not based on how long the seat tube is.  

A rider like me who wants a lot of saddle setback will need a longer TT than a rider of the same size who is happy with the usual upright seat tube of most modern smaller road bikes.  Does this make me a rando or my bike a French fit?  I think not.  

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Brad

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Dec 28, 2020, 10:32:04 AM12/28/20
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There are outer limits.  Finding a stem with more than 120 mm reach is one.  With bars level with seat, there are a limited number of ways you can set up the frame and parts in between without custom fabrication.  Compact frames are somewhat dependent on being able to either arch the neck up while in the drops, or see peripherally over the top of your glasses if you must wear them.   In my particular experience assuming I could adjust a frame with a 57 cm top tube by careful part selection was completely obliterated by the comfort I found with a 60 x 60 cm frame.   Pushing a seat 3 cm farther back is quite a challenge even with modern parts and seats and long setback seat posts are not as common as one might hope.  Then there is the challenge out of the saddle of getting your body mass close to the front axle.  Or in the alternative getting you body mass too far back on a really steep climb and flipping over backwards (been there, done that, not sure if it was on the 34 per cent grade or the 20 per cent grade of Hadley Road in Black River/Rutland NY).  The bottom line is people come in different sizes and bikes probably should, too. 

Mark in Beacon

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Dec 29, 2020, 8:12:42 AM12/29/20
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Well, compact frames will be more triangulated, therefore less flexible. They are generally also created with OS tubing. I think we all know what this implies.

A "French Fit" (aka "Kenfit") as I understand it is more about how you decide to pick your size in a traditional touring/rando  diamond frame, not necessarily the geometry or tubing arrangements of the frame itself. So a little apples to oranges, perhaps.

On Sunday, December 27, 2020 at 1:54:04 PM UTC-5 Murray Love wrote:

ericni...@gmail.com

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Dec 29, 2020, 8:44:50 AM12/29/20
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While frames with sloping top tubes may in principle be stiffer in various directions, the greater amount of exposed seatpost generally results in more vertical compliance at the saddle. This can be measured by statically loading the saddle and measuring the deflection. Part of the deflection is from the elastic bending of the exposed seatpost, and part is from a slight elastic rotation of the seat cluster. The stiffer the frame in the area of the seat cluster, the less the frame contributes to this “vertical compliance”. The shorter the length of exposed seatpost, the less its contribution to compliance.

Having measured this on several bikes, and also being challenged to find bikes tall enough to allow a “French Fit”, I’ve come to the conclusion that some top tube slope and with it, a bit more exposed seat post,  results in a more comfortable riding bike.

Eric in NH

Murray Love

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Dec 29, 2020, 9:02:47 AM12/29/20
to Mark in Beacon, 650b
I agree, Mark, but I was considering the question solely from a fit perspective. There's no reason you shouldn't be able to arrange the contact points on a compact frame identical to a level-TT frame, though in practice this often means tall spacer stacks and/or upward sloping stems. This is convenient for manufacturers, because it means they can offer fewer sizes, but it looks pretty ugly to me.

Murray
Victoria, BC

Steve Palincsar

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Dec 29, 2020, 10:07:07 AM12/29/20
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On 12/29/20 8:12 AM, Mark in Beacon wrote:
> Well, compact frames will be more triangulated, therefore less flexible.


More parallelogram and less triangular for most of them, which in theory
should be more flexible.  They may be less flexible, thanks to OS tubing
and shorter seat tubes, but the overall structure as a bicycle, with
seatpost and steerer inserted, may be more or perhaps less flexible than
a level top tube frame with identical contact points.

Mark in Beacon

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Dec 29, 2020, 10:46:03 AM12/29/20
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On Tuesday, December 29, 2020 at 10:07:07 AM UTC-5 Steve Palincsar wrote:
More parallelogram and less triangular for most of them, which in theory
should be more flexible. 

Maybe it's more parallelogram than diamond, but it sure looks to be triangulated.
(I was going to insert a photo here, but it looks like it is not an option in the 650B group?

Mark in Beacon

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Dec 29, 2020, 10:56:30 AM12/29/20
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On Tuesday, December 29, 2020 at 8:44:50 AM UTC-5 ericni...@gmail.com wrote:
While frames with sloping top tubes may in principle be stiffer in various directions, the greater amount of exposed seatpost generally results in more vertical compliance at the saddle.

Okay. I was implying the phenomena of planing, often reported on this list as being a feature of more flexible frames, in which the rider gets in harmonic resonance with the frame flex. This is often attributed in large part to the top tube wall thickness and diameter. Do you find a similar "in sync" response with a tall seat post? I don't have much experience with that setup. What is meant by vertical compliance?Just a shock absorption quality?

Cary Weitzman

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Dec 29, 2020, 5:16:05 PM12/29/20
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Mark in Beacon wrote:
> (I was going to insert a photo here, but it looks like it is not an
> option in the 650B group?
>
> https://cyclistzone.com/road-bike-compact-frame-vs-traditional-frame-which-ones-right-for-you/
>
Ignoring the fact that the Rocky Mountain Hammer frame shown as a
"compact road biker" is actually a 26" mountain bike.

Fortunately, the Moots further down is actually a good example of a
compact frame.

Cary
PTBO.ON.CA

Mark in Beacon

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Dec 29, 2020, 5:56:27 PM12/29/20
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              I had the Moots downloaded and ready to go, but no photos--in line or attached -- allowed in this forum? Has it always been so?

David Parsons

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Dec 29, 2020, 6:03:47 PM12/29/20
to 650b
Or, in a more 650b-specific compact geometry: my emergency randonneuse

(it's more of a English geometry -- traditional compact geometry has a vanishly tiny reach, while this machine has a 595mm TT and a correspondingly huge reach -- but the TT drops off quickly as any other compact frame does.  If I pump the tires up I can get it to resonate, but the chainstays dampen that in a hurry.)

-david "8/5/8 TT, 7/4/7 DT" parsons

Steve Palincsar

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Dec 29, 2020, 6:14:35 PM12/29/20
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No photos?   Really?


No "compact geometry" here.   And not traditional zero-seat post extension "French fit" either.

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David Parsons

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Dec 29, 2020, 6:18:37 PM12/29/20
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On Tuesday, December 29, 2020 at 3:14:35 PM UTC-8 Steve Palincsar wrote:

No photos?   Really?


How did you do that?   I go in via the web interface and the list of formatting items doesn't include anything to pull in a photo?

-david parsons

Steve Palincsar

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Dec 29, 2020, 6:31:23 PM12/29/20
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I don't use the web interface.  I post email messages created with Thunderbird.   In the case of that photo, I went to my flickr site, viewed the photo and did a screen capture to clipboard, and pasted the image into email.

The web interface is not the only way to post to the google group.

Harry Travis

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Dec 29, 2020, 7:58:35 PM12/29/20
to Steve Palincsar, 65...@googlegroups.com
I’ll wonder and ask if authorities /mods of the bike groups I subscribe to open the options for response within the web interface.

Google cannot be keeping these groups (mostly for serious work groups) to make it as difficult and discouraging as it has become for some. 

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On Dec 29, 2020, at 3:31 PM, Steve Palincsar <pali...@his.com> wrote:


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Steve Palincsar

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Dec 29, 2020, 10:06:44 PM12/29/20
to Harry Travis, 65...@googlegroups.com

I'm an admin on the iBOB list.  We don't have that kind of control over the web interface.    If only.

Ken Freeman

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Dec 30, 2020, 7:57:17 AM12/30/20
to Mark in Beacon, 650b
Assuming by Kenfit you mean me, I don't object, but I don't see it as appropriate.  I explained my preference to say "this is what good fit means for me," not to say "French fit is the style for me."  I can understand how it all works together especially if a big front bag (Ostrich for example) above the front wheel is desired.  The toes need clearance to the fender, and the bar needs to enable good access for the top bag, and the hands need to be where they need.  For long term ride comfort over a wide range of roads, I like to be able to lift my body up for shock isolation, and that is easiest with my CG centered over the BB.  For me that's a usable fit.  I also like a low BB and low Q, the pedaling just feels better.  

Looking from a stack/reach point of view, top tube is made up of the effective setback (distance along the effective TT from the axis of the seatpost to a line plumb with the BB axis), and the reach (with a small error at the head tube).  These can be separated by looking at the seat tube angle, the saddle setback required by the rider (similar to the UCI saddle nose setback), seat tube angle, and the saddle height measured along the seat tube.  Given those specs matched to a selected seat post and a selected saddle (the set back seat post and long-rail saddle Murray mentioned), I believe I can find a good saddle positioning on a Herse, a Mondonico (well almost!) and a wide range of other bikes.  

Some are just problems: all the vintage Treks I've measured and the specification lists from Vintage-Trek) show a 73 degree ST angle.  With a long-rail steel Selle Anatomica and a standard seatpost (like a SR LaPrade) it just about works.  With a long setback seatpost like a Nitto S-84 it works well.  But if I try a modular lighter-weight Selle Anatomica with the replaceable metal rails, I lose about 3 cm because the rail on those saddles does not match the older steel rail design.  SA's accommodation is to sell you the longer carbon rails.  

But I don't like my Trek 610 that much.  Much nicer are my 2013 650b Terraferma Super Corsa (same 73 degree seat tube) and my 1984-ish Mondonico with 74.5 or 75 degree seat angle), which likes tubulars 21 to 28 mm width.  Those both pedal so well that I accept the saddle arrangement compromises.  The Mondo is a typical stage-race geometry - it will never take a 650b, mudguards, front rack, or front bag.  But I can get very close to the same contact points as on the Terraferma.

This is an illustration that I don't just shoot for the randonneuse design, though I believe it has excellent utility and the Terraferma planes and handles well.  I also greatly enjoy a responsive lively road bike that fits me well.

For most of my bikes a Brooks Pro and B17 do not work too well.  A Swallow seems to have the widest part closer to the rear than a Pro or a B-17, so you get effectively some added setback with a Swallow.  On the Mondo in trainer use a Swallow is great, so some rethinking may be coming!  It has a narrow shallow platform which has huge lateral clearance near the back of the thigh.  I also have a 1952 Rudge Aero Special frame which has a 71 degree ST angle. I've test-ridden it a little with a Ideale 92 on it, and the saddle position does what I want.  Tubing is 1950s straight 531 but with long skinny stays and fork blades.  I expect a cushy ride but I don't know about planing.  We'll see!

Ken Freeman

Bill M.

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Dec 30, 2020, 10:17:37 AM12/30/20
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If I reply to a message on iBOB through the web interface I have an option to add an attachment or an image.  In the 650b group I only have text controls.  That implies some difference in how the two groups are set up.  Do others see the same thing?  

Bill
Stockton, CA

ericni...@gmail.com

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Dec 30, 2020, 12:59:36 PM12/30/20
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I made a comment about compact frames with their longer seat posts providing a benefit with respect to ride quality.  Mark then asked:

 Do you find a similar "in sync" response with a tall seat post? I don't have much experience with that setup. What is meant by vertical compliance? Just a shock absorption quality? 

With respect to planing (a.k.a. in-sync response, impedance matching, etc.), I don't know for sure.  Another way to pose that question would be: All other things held equal, would a longer seat post in a frame with a shorter seat tube "plane" as well as a shorter seat post in a frame with a longer seat tube?  

One way to think about a possible answer is to consider whether the planing sensation occurs during standing efforts as well as seated efforts.  If planing is apparent during standing efforts (where no loads are transferred into the frame via the saddle), then the relative vertical position of the seat cluster probably makes little difference by itself.  If planing is not apparent during standing efforts, then it may suggest that the larger front trapezoid and larger rear triangle of a level top-tube frame allow more torsional twist (again, all other things like tubing diameter and thickness held equal). I can't answer this because I'm a poor judge of what constitutes planing.  Bikes that fit me are rare enough that I've never had the good fortune to ride multiple bikes with different geometry and tubing dimensions back-to-back, to separate the variables.   
     
By vertical compliance, I mean elastic deflections in the vertical direction. Think of the bike as a series of springs, all stacked together.  A bump in the road needs to travel through each of these springs (tire, wheel, frame, seat post, saddle, shorts pad) on its way to your sit bones. I hesitate to call this "shock absorption" because that often connotes energy absorption, much like the shock absorbers (dampeners) in your car. They actually absorb energy through hysteresis. Some racing shocks even have cooling fins to dissipate the significant heat they harvest from conversion of kinetic energy. So we're not talking about absorbing shocks as much as allowing that movement to occur somewhere other than your backside.  This may sound like technical hair-splitting, but the difference is important.  Absorption = motion attenuated by converting kinetic energy into heat. Elastic deflection = motion attenuated with little or no energy loss. The first takes energy away from forward motion, the second does not. 

A long cantilevered seatpost may have questionable aesthetics to some, but it does bend in a beneficial, elastic way under static loads (sitting) and dynamic loads (bumps). In recent years, some of the major bike brands have attempted to increase vertical compliance at the saddle by redesigning the seat cluster to allow it to rotate more freely.  

Eric in NH      

njh...@gmail.com

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Dec 30, 2020, 3:13:49 PM12/30/20
to 650b
Yes, there is a difference between the web interface on the iBob and 650b groups. Using the same browser on the same PC, when posting to the iBob group, on the right of the "Post message" button there are three icons, for "Toggle rich text control", "Add attachment", and "Insert photo attachment". On 650b, there is only the "Toggle rich text control" icon. I have no idea why the difference, but it would be useful to be able to attach photos with the 650b web interface.

Nick Payne

ThermionicScott

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Dec 30, 2020, 5:28:44 PM12/30/20
to 650b
Testing... 


My browser doesn't give me an explicit option to add a photo attachment, but I can paste it from the clipboard (assuming this worked.)

- Scott

Mark in Beacon

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Dec 31, 2020, 12:22:53 PM12/31/20
to 650b
Maybe not, but as others have pointed out, other groups have controls for both adding an in-line photograph and for including an attachment in a post. I don't have Thunderbird and I don't post from my email, nor do I want another software or to post from email. So yes, I am explicitly referring to the web interface. It strikes me as  odd that this group interface does not have these features, yet other presumably identical groups do. A mystery wrapped up in a 650B.

Mark in Beacon

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Dec 31, 2020, 12:30:55 PM12/31/20
to 650b
Hi Ken. No hidden motives, apologies for being inappropriate! I only referred to Kensfit because you did!;^) Perhaps I misunderstood your rhetorical. No harm no foul. Happy New Year!

Ken Freeman wrote: Would you call it a French Fit because of the seat tube, or the long front-center, or what?  Why not just call it Ken's Fit? 
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