Pros' frame sizes

Questions about bike hire abroad and everything light bike related. No off-topic chat please

Moderator: Moderator Team

clm2206
Posts: 210
Joined: Wed Oct 24, 2007 6:56 pm

by clm2206

Hi

Since five years ago or so I've noticed there is an increasing trend to use smaller frames on pro bikes. On one hand it's reasonable, a smaller frame means more stiffness, less weight and lower center of gravity.

Alessandro Ballan's Willier LeRoi is the most vivid case of what I'm talking about. Even not being a sloping frame, he is a very tall guy (1.93 m) and his bike is only 54 cm center-top.

Any other tech reason for choosing the smallest possible frame?

Regards

Deruneinholbare
Posts: 152
Joined: Sun Feb 13, 2005 3:02 pm
Location: Linköping, Sweden

by Deruneinholbare

maybe they need the short headtube
carbon frams are often not custom sized for the pros

by Weenie


clm2206
Posts: 210
Joined: Wed Oct 24, 2007 6:56 pm

by clm2206

Deruneinholbare wrote:maybe they need the short headtube
carbon frams are often not custom sized for the pros


That's for sure, they need short head tubes to obtain the appropiate saddle-handlebar height difference. Besides that, they are thin and flexible athletes, so having their torso parallel to the floor is not an issue at all.

User avatar
CharlesM
Posts: 5771
Joined: Tue Sep 26, 2006 12:37 am
Location: Phoenix Arizona

by CharlesM

If you speak to lots of team mechanics, the trend is not for smaller or lower...

That type of frame sticks out a bit more and is noticed, but the sizing trend in general has been to have saddle to bar drops that are less drastic than they were a few years ago.

They're still lower and longer than 80% of riders should have to perform best, but the trend has been moving to less reach and not as drastic a drop for the last 4+ years.

That said, when you do see a guy that feels the need to go "a$$-up" the bikes today are simply aimed more to where they should be... And stand out even more than they used to.

In fairness it should be more of a test for a small percentage of pro's to get a proper fit if it means a larger percentage of wanna-be's get the bike they need.

clm2206
Posts: 210
Joined: Wed Oct 24, 2007 6:56 pm

by clm2206

As you say, I've noticed less reach (understood as horizontal distance between tip of the saddle and handlebar) but at the same time more height difference between saddle and handlebar in these years. Instead of stressing their back, arms and neck forward to achieve a flat torso, they tend now to lower their hands to have a more relaxed position. It makes sense.

I really don't remember where, but I'm pretty sure I've once read that modern frames are designed to sit on the wheels instead of the bottom bracket.

User avatar
Warblade
Posts: 1715
Joined: Tue Jan 10, 2006 1:20 am
Location: Seattle, Wa
Contact:

by Warblade

CLM -- I'm not exactly sure where you got those measurements, but according to CyclingNews, his top tube length in 580mm with a 135mm stem. His seat tube length in 545mm C-C or 560mm C-T. I am assuming these measurements are correct.

With those measurements, there is absolutely no way he could be riding a 540mm top tube. Now if you were talking about seat tube length, then I'm not so sure what the fuss is about. As long as he's comfortable standing over the top tube, then there is nothing to worry about. Seat tube height has little to with fit. Seat tube angle, head tube angle, top tube length, reach, stack, and set back are all much more important than seat tube height.

Now you could argue that the taller the seat tube is, the longer the top tube will be, but in this particular case I think it is negligible.

Ballans Bike via CyclingNews
www.ChrisDiRe.com

Adam Hansen wrote:Sponsors should not have to go, its the doped riders that should be shot instead, in the knee caps would be nice.

User avatar
strobbekoen
Posts: 4473
Joined: Wed May 18, 2005 6:24 pm
Location: BELGIUM

by strobbekoen

I don't think there is anything particular small about that setup at all. cyclingnews posted quite a few pro's setups and I never noticed them to be out of the ordinary, apart from the occasional huge drop. However, not all pro's ride with a huge drop either. I think the OP meant the seattube, which indeed is no criterium for size. If it's the toptube, I'd like to see him on a 54, worth a laugh or two i think :lol:

clm2206
Posts: 210
Joined: Wed Oct 24, 2007 6:56 pm

by clm2206

Hi again

Sorry guys, my fault. Anyway, 56 center-top (seat tube) on standard geometry is a bit on the short side for a 1.90 m rider.

Such a size for a pro rider was uncommon in, let's say, 2001, where only riders as Bartoli used to ride a small frame.

Regards

User avatar
ultimobici
in the industry
Posts: 3442
Joined: Sun Nov 21, 2004 2:45 pm
Location: London, UK
Contact:

by ultimobici

clm2206 wrote:Hi again

Sorry guys, my fault. Anyway, 56 center-top (seat tube) on standard geometry is a bit on the short side for a 1.90 m rider.

Such a size for a pro rider was uncommon in, let's say, 2001, where only riders as Bartoli used to ride a small frame.

Regards
But if you look at the pic you can see that the bike is on a side stand so is actually slightly sloping. Not unusual at all.

User avatar
Koen
Posts: 343
Joined: Thu Sep 07, 2006 6:31 pm
Location: Aalst (Belgium)

by Koen

how smaller the frame, how lower the point in which the mass is concentrated (don't know the world in english, mass centre point?). how lower that point, how easier it is to go with high speed through corners maybe?
Gewoon bluve goan!

User avatar
strobbekoen
Posts: 4473
Joined: Wed May 18, 2005 6:24 pm
Location: BELGIUM

by strobbekoen

Why ? A smaller frame for the same rider requires a longer seatpost, a longer stem, and more spacers all of which are well above the center of gravity. The differences in that respect would be minor if you ask me. The biggest difference would be handling as the wheelbase and the relative position of the wheels with regards to the rider would change.


User avatar
HammerTime2
Posts: 5474
Joined: Thu May 04, 2006 4:43 pm
Location: Wherever there's a mountain beckoning to be climbed

by HammerTime2

If you want a low center of gravity (that's how you say it in English), get a heavy bike, not a light bike.


clm2206
Posts: 210
Joined: Wed Oct 24, 2007 6:56 pm

by clm2206

HammerTime2 wrote:If you want a low center of gravity (that's how you say it in English), get a heavy bike, not a light bike.


A heavy frame, not the entire bike.

That is not true, because everything remaining constant, dropping down the top tube (via sloping or a smaller frame size) will lower the center of gravity.

With a bigger or a smaller frame, the seatpost will remain in the same position for the same rider, although will protrude more in the latter.

The only thing that will increase the mass above the CG in the small frame will be the longer stem, but I believe its impact is negligible, compared to the mass of the frame. (10:1 proportion, more or less).

So, choosing a smaller frame do result in a lower CG.

Regards

by Weenie


Post Reply