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Do I need frame suppleness with 28mm tires?

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Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Do I need frame suppleness with 28mm tires?

Old 03-07-19, 12:34 PM
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Originally Posted by RChung
Josh has some pretty cool stories about testing tire pressure and rolling resistance for Paris-Roubaix. To make sure they hit the right resonance frequency they had to test over the Arenberg at full speed. As an aside, do you recall the win streak that the Rock Shox Ruby road fork had at Paris-Roubaix? Ever wonder why the peloton stopped using them? https://www.bikehugger.com/posts/roc...y-years-later/
Yeah, between his Zipp days and what he's doing now, the man has a lot of good data. What I especially appreciate is how he translates that into a usable process.

I had forgotten about Rock Shox on road bikes. That's a great link.

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Old 03-07-19, 12:57 PM
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Originally Posted by JohnJ80
A *big* part of the compliance for any bike is in the "properly inflated" tire comment. According to the podcast, most people do not properly inflate their tires and do, in fact, over inflate them considerably. I'd bet pretty heavily that that is a bigger factor than the Domane elastomers in the frame - at least it did on my daughter's Domane.

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You'd lose pretty heavily. There are no elastomers in the Domane frame. IsoSpeed is essentially pivot points that give the Domane a very long seatpost and a very long steerer. They do an incredible job of deflecting the brunt of the hits. Also, as I stated previously, my Domane with 30mm tires at 65/70psi (front/rear) is more comfortable, in terms of taking the jolt out of bumps/cracks/potholes, than my gravel bike with 38mm tires at ~40psi.

Again, I'm not arguing against tire compliance, just saying that it's false to say that any ol' road bike with 28s will get you the same kind of compliance as a Domane (and potentially a Roubaix, but I have no experience there).
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Old 03-07-19, 01:04 PM
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Originally Posted by WhyFi
You'd lose pretty heavily. There are no elastomers in the Domane frame. IsoSpeed is essentially pivot points that give the Domane a very long seatpost and a very long steerer. They do an incredible job of deflecting the brunt of the hits. Also, as I stated previously, my Domane with 30mm tires at 65/70psi (front/rear) is more comfortable, in terms of taking the jolt out of bumps/cracks/potholes, than my gravel bike with 38mm tires at ~40psi.

Again, I'm not arguing against tire compliance, just saying that it's false to say that any ol' road bike with 28s will get you the same kind of compliance as a Domane (and potentially a Roubaix, but I have no experience there).
Others have different experience, and I would tend to believe them - the amount of compliance available in 'decoupled' frames is still miniscule compared to the suspension available in properly inflated 40 mm tires. Methinks you may be discounting other factors that change between the bikes, or experiencing bias confirmation when interpreting the results of your comparison.
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Old 03-07-19, 01:18 PM
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Originally Posted by Wilfred Laurier
Others have different experience, and I would tend to believe them - the amount of compliance available in 'decoupled' frames is still miniscule compared to the suspension available in properly inflated 40 mm tires. Methinks you may be discounting other factors that change between the bikes, or experiencing bias confirmation when interpreting the results of your comparison.
Ah, the 41.
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Old 03-07-19, 05:34 PM
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Originally Posted by WhyFi
You'd lose pretty heavily. There are no elastomers in the Domane frame. IsoSpeed is essentially pivot points that give the Domane a very long seatpost and a very long steerer. They do an incredible job of deflecting the brunt of the hits. Also, as I stated previously, my Domane with 30mm tires at 65/70psi (front/rear) is more comfortable, in terms of taking the jolt out of bumps/cracks/potholes, than my gravel bike with 38mm tires at ~40psi.

Again, I'm not arguing tire compliance, just saying that it's false to say that any ol' road bike with 28s will get you the same kind of compliance as a Domane (and potentially a Roubaix, but I have no experience there).
You're mischaracterizing what I was saying. I never said that a rigid frame road bike with 28s will have the same compliance as a Domane or a Roubaix. Clearly, added compliance in the form of a spring in the frame of those bikes PLUS properly inflated tires (and I'm presuming their are the same size or this is meaningless) would be better. The question is just how much better is it?

What I am saying is that the tires are a big part, if not the biggest part by a fair amount, of ride compliance in the whole equation. I think you'd agree the tire inflation should be optimized in any road tires without regard to the frame. Just looking at it though, you may want to consider dropping the pressure on both your bikes using Poertner's process and then revisiting the whole issue - your tire pressures don't look optimized to me which could be a big part of the ride compliance difference in your two bikes.

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Old 03-07-19, 07:32 PM
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Originally Posted by JohnJ80
You're mischaracterizing what I was saying. I never said that a rigid frame road bike with 28s will have the same compliance as a Domane or a Roubaix.
I was restating the premise of the thread.

Originally Posted by JohnJ80
What I am saying is that the tires are a big part, if not the biggest part by a fair amount, of ride compliance in the whole equation. I think you'd agree the tire inflation should be optimized in any road tires without regard to the frame.
Disagree with the bolded, at least w/r/t the specific bikes being discussed, the Domane in particular.

Originally Posted by JohnJ80
Just looking at it though, you may want to consider dropping the pressure on both your bikes using Poertner's process and then revisiting the whole issue - your tire pressures don't look optimized to me which could be a big part of the ride compliance difference in your two bikes.
Oh? And what do you and Mr Poertner say my pressure should be? They're both high yet you think that the delta is irrelevant in comparison?
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Old 03-07-19, 09:43 PM
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[QUOTE=WhyFi;20827916]I was restating the premise of the thread.



Disagree with the bolded, at least w/r/t the specific bikes being discussed, the Domane in particular.
[\quote].

Well, we disagree.


Oh? And what do you and Mr Poertner say my pressure should be? They're both high yet you think that the delta is irrelevant in comparison?
Not necessarily, but your tire pressures look high and probably not optimal to me. What you do with that is up to you although the comment on my part was simply trying to be helpful (I won't make that mistake again).

That said we have absolutely no way of knowing how your bikes ride comparatively unless either you explained how you optimized them or someone tested them and we had some data. But, apparently you're not interested in doing that and I have no interesting in spending any more time on your bike tire inflation. So that's probably the end of it.

Now that we've beat that to death and established that we don't agree.....
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Old 03-08-19, 07:15 AM
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Originally Posted by JohnJ80
Well, we disagree.
Yup, but one of us has experience with one of the bikes in question and knows about the deflection possible within the frame design (hint: it's greater than the height above the rim of properly inflated 28mm tires).

Originally Posted by JohnJ80
Not necessarily, but your tire pressures look high and probably not optimal to me.
Based solely upon the pressure and the tire size. Yeah.

Originally Posted by JohnJ80
What you do with that is up to you although the comment on my part was simply trying to be helpful (I won't make that mistake again).
Your attempt to be helpful was built on the foundation that assumes my ignorance.

Originally Posted by JohnJ80
That said we have absolutely no way of knowing how your bikes ride comparatively unless either you explained how you optimized them or someone tested them and we had some data. But, apparently you're not interested in doing that and I have no interesting in spending any more time on your bike tire inflation. So that's probably the end of it.
Nope. You don't have a way, which is why I found in interesting that you simply assumed that I was wrong. Maybe people would be more responsive to your "helpful" attempts if you don't first talk down to them? Just a thought.
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Old 03-08-19, 07:32 AM
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Originally Posted by WhyFi

Nope. You don't have a way, which is why I found in interesting that you simply assumed that I was wrong. Maybe people would be more responsive to your "helpful" attempts if you don't first talk down to them? Just a thought.
Wow. I didnt assume anything. I just thought your inflation numbers looked a little off. That’s it. And that’s also about as much as I care about it too.

FWIW, we have a Domane in the household so we do have experience with it (false assumption on your part maybe).

And as for condensending attitude - right back at you. Talk about making assumptions? Look in the mirror.

Have a nice day.

Last edited by JohnJ80; 03-08-19 at 07:36 AM.
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Old 03-08-19, 08:20 AM
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Originally Posted by JohnJ80
Wow. I didnt assume anything. I just thought your inflation numbers looked a little off.

The bolded is an assumption. What's my riding weight? What's my goal? What surfaces am I riding on? What are the bike configurations? Which tires am I using? What's the interior rim width and how does that affect volume?

You know what - I'm willing to let it go and take your word that you were trying to be helpful, but you were still working with at least one major blind spot and it would have been nice if you would have asked me about that before telling me that I was doing it wrong - that didn't sit well with me and it's a big reason that the conversation has gone the way it's gone. I can assure you that my numbers are not far off and that I'd need to get *way* more persnickety for minimal gain. As I'm not being edged out in TTs, the ROI for that endeavor just isn't there.

Originally Posted by JohnJ80
FWIW, we have a Domane in the household so we do have experience with it (false assumption on your part maybe).
No, I recalled that. It's your daughter's, you described it as having elastomers. I don't know which model she has or whether it's a current model with both front and rear Iso. Maybe she's a flyweight that doesn't flex the system, but what you describe isn't consistent with my experience or that of many others that I've interacted with. I will say that the system doesn't hit you over the head, which is the beauty of it, and that it's most noticeable to me when I'm riding a bike that doesn't have it.

Originally Posted by JohnJ80
Have a nice day.
You too. Not looking forward to the additional snow this weekend. I'm done with winter and I think that it's getting old even for the fat bikers in my crew.
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Old 03-08-19, 08:22 AM
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Originally Posted by WhyFi
You too. Not looking forward to the additional snow this weekend. I'm done with winter and I think that it's getting old even for the fat bikers in my crew.
No need to body shame.
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Old 03-08-19, 08:29 AM
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I've done some sprints on a Trek Checkpoint recently, and I am presently a shade under 200 lbs. I did not notice any flex in the frame while putting power down on the pedals, but the Checkpoint has rear Isospeed only (basically a longer seat post attached to the bottom bracket, but "de-coupled" from the seat and chain stays. The frame is still quite stiff.

A lot of current research is saying that tire size and pressure is the largest factor in terms of ride "suppleness", and my experience is that this is true. I frequently gravel ride on a stiff aluminum frame, and I have noticed a MASSIVE difference since switching to larger tires with lower pressures. In fact, it has me reconsidering my previous avoidance of aluminum frames. You can potentially save a boatload of money in this sport by riding aluminum frames instead of carbon fiber, so I do think this question is of paramount importance.
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Old 03-08-19, 10:12 AM
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Originally Posted by HarborBandS
I've done some sprints on a Trek Checkpoint recently, and I am presently a shade under 200 lbs. I did not notice any flex in the frame while putting power down on the pedals, but the Checkpoint has rear Isospeed only (basically a longer seat post attached to the bottom bracket, but "de-coupled" from the seat and chain stays. The frame is still quite stiff.

A lot of current research is saying that tire size and pressure is the largest factor in terms of ride "suppleness", and my experience is that this is true. I frequently gravel ride on a stiff aluminum frame, and I have noticed a MASSIVE difference since switching to larger tires with lower pressures. In fact, it has me reconsidering my previous avoidance of aluminum frames. You can potentially save a boatload of money in this sport by riding aluminum frames instead of carbon fiber, so I do think this question is of paramount importance.
I had the same thought recently. My last experience with aluminum was a stiff Cannondale road frame with 23mm tires - never again! But, if I can fit some big, bouncy tires onto an aluminum frame I might give it a try with a 'project bike'. I saw an '88 Cannondale 'Red Shred' MTB frame on CL recently - might be fun with some 50mm+ Compass or Soma tires.


This is a web pic of a built-up 'Red Shred'.
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Old 03-08-19, 11:03 AM
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Originally Posted by jlaw
. I saw an '88 Cannondale 'Red Shred' MTB frame on CL recently - might be fun with some 50mm+ Compass or Soma tires.


This is a web pic of a built-up 'Red Shred'.
That bike might not be the best choice. It's BB is almost 13" high.
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Old 03-08-19, 04:52 PM
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Originally Posted by noodle soup
That bike might not be the best choice. It's BB is almost 13" high.
For a drop bar conversion how does the BB height come into play? Just wondering.
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Old 03-08-19, 10:04 PM
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Originally Posted by jlaw
For a drop bar conversion how does the BB height come into play? Just wondering.
Handlebar choice is irrelevant, but a very tall BB means that the rider's weight will be higher up than normal, and likely less stable.

IIRC, that frame was designed to be an East Coast(tight woods) bike, and it was quite twitchy at higher speeds. Not exactly what I would want for a drop bar conversion/gravel bike.

This will show you the geometry of the frame(SM800)

https://vintagecannondale.com/year/1991/1991.pdf
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Old 03-09-19, 01:21 AM
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Havnt read the other answers, but in my opinion/experience the tire size is only indirectly responsible for comfort or lack thereof. Its really the tyre pressure, and a wide tyre rides no better, at the same pressure, than a skinny one. Now the caveat is, depending on your weight and road surface, you may or may not need wide tyres to go with lower pressure, say 85 psi. Wider tyres give you a little more "room" to play around and really has no down sides besides a little more weigh.
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Old 03-09-19, 06:23 PM
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Originally Posted by noodle soup
IIRC, that frame was designed to be an East Coast(tight woods) bike, and it was quite twitchy at higher speeds. Not exactly what I would want for a drop bar conversion/gravel bike.
"Twitchy" would probably be relative to most non-NORBA-era mountain bikes. Drop bars tend to lend bikes a narrower stance and less leverage over the steering that most MTB bars, so the front-end geo might actually be reasonable for a conversion. Drop-bar conversions of early-80s and modern MTBs often have an uncomfortable amount of trail and wheel flop.
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Old 03-09-19, 07:01 PM
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Originally Posted by HTupolev
"Twitchy" would probably be relative to most non-NORBA-era mountain bikes. Drop bars tend to lend bikes a narrower stance and less leverage over the steering that most MTB bars, so the front-end geo might actually be reasonable for a conversion. Drop-bar conversions of early-80s and modern MTBs often have an uncomfortable amount of trail and wheel flop.
13" high BBs were never common. One of my old friends had this bike, and it was unlike anything available at the time. It was designed for handling the tight, twisty, rooted trails of the NE. It was unlike anything else on the market at the time.

It's more of a trials bike, than a trail bike.

It's a really cool bike(and I'd love to own one), but not one that I would want to convert into a gravel bike.
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