Racing Bike sizing.

[Rollon]

Ive had my road bike for acouple of years now after not having cycled for over 30 years.
I got advice on frame size from the cycle store who are very knowledgeable.
It was afair old stretch at first on the drop handle bars, even on the brake hoods, but eventually my back got more used to the position and is fine now.
However watching the Tour De France and others races lately, a lot of the racing bikes look really small when closely looking at riding positions.
I was wondering, is it a common practise to race these type of races with what would normally be considered an undersized frame?
Dave.

 

[Simba]

Hard to say without knowing how tall you are.

 

[smokeysmoo]

Pro teams tend to use very compact, (undersized as you say), frames. I've always presumed the reason is weight. If you look at TDF photos from the 60's, 70's and 80's you'll see larger frames with much less visible seat posts, whereas nowadays it's all compact frames, sloping top tubes and loads of seat post.

Personally I hanker after the old days as far as geometry is concerned, I really don't like sloping top tubes and compact frames, but then again I am 6' 5" and the wrong side of 17 stone

 

[fossyant]

Older frames like smokeysmoo says are bigger. My two old school frames are 56", but I take a 52-54 (equivalent size) in a compact frame/sloping top tube.

So long as your position is the same, you won't have issues of fit. My older bikes are more of a stretch, but less of a drop to the bars. My new bike is a bigger drop, but less of a stretch - works out about the same for reach.

 

[brockers]

I was wondering, is it a common practise to race these type of races with what would normally be considered an undersized frame?
Dave.

Yes. Some examples. Contador uses a 53cm and he's 5'10. I use a 53cm frame and I'm 5'7''! Mark Cavendish at 5'8'' sits on a 52 (a regular racey-type of that height might use somewhere around a 54cm). I remember Paolo Bettini (the World Road Race champ a few years ago), who at 5'7'' preferred to size down from a 52cm Specialized to a 49cm. I was in Condor a couple of months ago and the assistant tried to flog me Dean Downing's ex works Rapha Condor bike. He's an inch taller than me, but the frame was tiny with tons of seat-post showing. (Could even have been a 49cm - some sort of Deda carbon job that Condor stick their name on.) Having a smaller frame is, or at least as much to do with being able to have a lower stem and bars than weight.

 

[snailracer]

Longer seatpost (on a compact frame) is also more comfy, saddle-wise.

 

[Rollon]

Thanks for all your replies, I wasn't imagining it then.
Another thing i noticed is that the knee movement on most riders seemed far less (Up and Down) than my own. I can only assume that the crank length is shorter. Obviously less rise and fall motion makes for more endurance, I would think, but harder work in some circumstances.
Dave.

 

[brockers]

Thanks for all your replies, I wasn't imagining it then.
Another thing i noticed is that the knee movement on most riders seemed far less (Up and Down) than my own. I can only assume that the crank length is shorter. Obviously less rise and fall motion makes for more endurance, I would think, but harder work in some circumstances.
Dave.

are you absolutely sure your saddle is at the right height? Crank lengths realistically range between 170mm and 177.5mm, and it's extremely unlikely you'd spot a 2.5 or 5mm difference on a TV screen. Many, if not most, people can't even feel the difference. Is it possible you might think that the riders on the telly have shorter cranks by the way they pedal? They push easy gears at 90-100rpm, what the French call 'souplesse' (suppleness). Most beginners (and those who've not ridden with racing cyclists) tend to constantly mash big gears at around 60rpm, mistakenly believing that because doing so hurts your legs, it must be making you go faster.

 

[snailracer]

Thanks for all your replies, I wasn't imagining it then.
Another thing i noticed is that the knee movement on most riders seemed far less (Up and Down) than my own. I can only assume that the crank length is shorter. Obviously less rise and fall motion makes for more endurance, I would think, but harder work in some circumstances.
Dave.

This is because those riders are riding as far back on the saddle as they can, and their saddles are mounted as far back as the saddle clamps will allow. Their knee movement is therefore less up/down and more back/forth, in relation to the horizontal, however the total knee movement is unchanged and depends only on crank and leg lengths.

Many TdF riders set up like this to be more aerodynamic, emulating the position on a recumbent as far as they can, whilst riding bikes that are geometrically UCI-legal (i.e non-recumbent "uprights").

 

[Zoiders]

A compact frame is not really "smaller".

This is a misconception which leads to people being on frames with far too much reach.

The seat tube got lower yes, this shortens the seat stays as well as the seat tube and makes the rear triangle stiffer and a little bit lighter - the actual effective reach of the frame, what is known as the virtual top tube length needs to remain the same.

Imagine a horizontal line running from the top of the head tube back to the seat post, that's the measurement you are looking for on most compact frames.

 

[cyberknight]

And the pros tend to run longer stems as well as having a minimum saddle setback of 5 cm .

 

[Rollon]

Thanks very much Guys, it is all beginning to make sense now.
Dave.