undersized road bike frame trend in professional ranks

[offbyone]

Been watching a lot of racing and what I am seeing is that most of the pros are running what appears to be at least 1 frame size too small with tall seat posts and long stems (>110).
I am perplexed by this. Am I imagining this?

Back in the day riders would often get the size smaller to save frame weight. But now weight is no longer an issue as it is easy to make a modern bike meet the UCI limit.

I always thought running an excessively long stem like 120+ would hurt bike handling characteristics.
Does anyone have insight on this trend?

 

[macbindle]

Small frames are stiffer. Long seatposts=comfort

 

[JayKosta]

Re:

Small frames are stiffer. Long seatposts=comfort

----------------
Or, full-sized carbon frame with moderate seatpost length would be too stiff / uncomfortable.
Small carbon frame is plenty stiff for power application, and long stem & seatpost enable desired position & comfort.

Jay

 

[offbyone]

Re:

Small frames are stiffer. Long seatposts=comfort

You are telling me there is a significant stiffness difference between say a 54 and 56 or 54 and 58 modern carbon frame?

 

[macbindle]

Yes

 

[jmdirt]

Smaller carbon frames are not stiffer than larger ones. The carbon layup determines stiffness and you can bet that the size run is either identical in every measure of stiffness and ride comfort, or if anything, stiffer on larger frames within a model.

As to why pros ride a certain size: preference, superstition, recommendation, tradition...

 

[macbindle]

Assuming that designers account for this (which some do to a greater or lesser extent), yes. All other things being equal smaller frames with same diameter tubes will be stiffer. Also depends on their starting point size for design.

 

[jmdirt]

I'm not trying to bust your chops here mac, but you are talking about old school steel frames. Carbon manufacturing is a different beast. The manufacturers who have the money to be in the protour either know how to control factors/charactoristics like stiffness, or have "sub contract engineers" who do.

Note: even steel (by the '80s), Ti, and AL frame manufacturing accounted for frame size with tube wall thickness, size (ID/OD), shape, butting, etc.

 

[macbindle]

No chops busted

 

[winkybiker]

The deflection at the handlebars and seat will be greater for small frames running long stems and seat-posts compared to more conventional sizing, although the actual frame deflections at the BB relative to the hubs may be smaller. But that's not why they run small frames. They do so to get a short head-tube so they can get their bars low. Modern bikes have increasingly tall head-tubes to suit the MAMIL crowd. Custom sizing is rare in carbon (but not unknown). Trek's H1/H2 fit options are a solution.

It is my observation that head-tubes for many riders are still not nearly tall enough. Riders run stacks of spacers, upside-down, priapic stems and STILL never get into the drops.

 

[froze]

They been riding one size smaller frames for as long as I've been alive and I'm 65, so that probably means they've riding smaller frames for a lot longer than I've been alive. It's always been about frame flex, and smaller frames flex less, which that thing is odd since the most flexy bike ever raced was the Vitus 979 ridden by Sean Kelly and it didn't seem to cause him to lose...in fact he won the TDF.

 

[Giuseppe Magnetico]

Re:

They been riding one size smaller frames for as long as I've been alive and I'm 65, so that probably means they've riding smaller frames for a lot longer than I've been alive. It's always been about frame flex, and smaller frames flex less, which that thing is odd since the most flexy bike ever raced was the Vitus 979 ridden by Sean Kelly and it didn't seem to cause him to lose...in fact he won the TDF.

Of course there comes a point where rider and machine have a divergence to where you could put said rider on any relevant bike of the time and will win. Kelly would have won on any bike of his era. However, we're dealing with carbon instead of steel or alu now. But even in the metal era tubing mixes and shapes made properly sized frames stiffer. For example, in the early 80's the Colnago Master came to because Giuseppe Saronni wanted a stiffer bike than the Super he was riding, not a smaller size. So Ernesto had Columbus produce that famous diamond shaped Columbus Gilco main triangle tube set. I've had both models and still have my Master, the ride between them is starkly different in terms of stiffness! Similar tubing and lug experimentation was happening across all manufacturers.

So with carbon manufacturing there is far more control with layup to keep ride quality and stiffness relatively consistent through the fat part of the size range. Going from a 56 to a 54 isn't done to achieve stiffness or lighter weight even. winkybiker and jmdirt got it right here earlier in the conversation, the main reason pros are sizing down in the carbon frame era is stack height, not stiffness.

 

[Bolder]

I'd also guess that a longer seatpost, whether integrated or not, gives a little bit of cushion. It may not translate into loss of efficiency if the bb area is laterally and vertically stiff. Also, all things being equal it's a bit easier to control a smaller frame, and if the hard points are to a rider's preference, then frame size probably doesn't matter +/- 2 cm. Stack height...hmmm, I'd think we're talking only a few mms either way between, say, 54/56 cm. but maybe enough to matter.

If between frame sizes I always go down, assume the pros are the same way. It could also be the belief that a lighter frame is better and any weight needed to reach UCI minimum is best apportioned among various components.

 

[42x16ss]

I’ve always thought that it was about 2 things - stack height and increased seat post for comfort.

 

[Angliru]

Re:

They been riding one size smaller frames for as long as I've been alive and I'm 65, so that probably means they've riding smaller frames for a lot longer than I've been alive. It's always been about frame flex, and smaller frames flex less, which that thing is odd since the most flexy bike ever raced was the Vitus 979 ridden by Sean Kelly and it didn't seem to cause him to lose...in fact he won the TDF.

Just for the sake of accuracy, Kelly won the Vuelta, never a TDF. He won the points classification at the Tour but not the general classification.

 

[masking_agent]

Been watching a lot of racing and what I am seeing is that most of the pros are running what appears to be at least 1 frame size too small with tall seat posts and long stems (>110).
I am perplexed by this. Am I imagining this?

Back in the day riders would often get the size smaller to save frame weight. But now weight is no longer an issue as it is easy to make a modern bike meet the UCI limit.

I always thought running an excessively long stem like 120+ would hurt bike handling characteristics.
Does anyone have insight on this trend?

Yes I've noticed that too. But a few teams (ie Sky, EF drapac and Astana) are not running high seat posts with their Pinarello F10's. I was watching Kwiatowski last Vuelta stage, and he's riding a pretty fair to low saddle height.

 

[ustabe]

Towards the middle of the '90s race based road bikes did get longer in the top tube for a given size, so riders did size down to maintain a manageable reach. Also, the handlebars are dropped lower to compensate for the raising of the brake (dual control lever) hoods, where the hands are most of the time. The tops of the handlebar are flat and level with the levers, and handlebar drop has decreased markedly. Also, some teams are using bikes with somewhat extended head tubes, so riders downsize to compensate for this.

But in general, I have noticed that pro riders appear to be riding with a lower, closer in hand position than was common especially during the Hinault-through-Armstrong period. This is reflected in the differences between the competitive fit and Eddy fit at competitivecyclist.com

 

[Leinster]

Re:

Small frames are stiffer. Long seatposts=comfort

Smaller frames have lower front ends. A slammed 100mm stem on a 56 is 2cm higher than a slammed 120mm stem on a 54. You don't see many pros on these undersized frames with a load of spacers under their stem.