Cervelo Fit Issue

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

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by konky

This is a cautionary tale regarding bike fits. The truth is two people with exactly the same body shape will most likely require two totally different bike setups. Just look at a pro peloton. Some riders are stretched out, some aren't. Most bike fits measure an anatomy and stick the measurements in a computer. Result, wrong bike fit.
Last edited by konky on Sun Oct 21, 2012 9:58 pm, edited 2 times in total.

by Weenie

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Hincapie wrote:
r_mutt wrote:you can't compare yourself to a pro as no only do most of the pros have flexibility beyond the ww (not weight weenie, weekend warrior), but most of them size down to get the lower head tube height (for aerodynamics). that would be uncomfortable for the working stiffs who don't ride 700 Km per week.

There are many people on cycling forums that say this, but I don't see why all pros would sacrifice comfort for aero, especially when most of them are riding behind a wheel most of the time. They all ride pretty much the same cockpit setup but they can't all be equally flexible. Everyone has their own genetic limitations and riding can improve on that but no amount of riding can help you exceed your limitations. So I still don't get all the small bikes.

My arguement for years now!
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If you believe in what Gerard V says about pro positions, he believes they have changed from years past and that they should come up.

I have to agree to a certain extent. The past two seasons, although I am 5'-9" with a 84.3cm inseam (Yes, I just mixed standard and metric), I have raced a 54 TREK. At first, you would not think that would be that off, but each season, I have migrated to racing it with a 140mm stem, at least 30mm of stack and the saddle height is maxed out. This would lead me to believe that I need to go up a size to get a similar fit without the long stem and stack. The bike did not handle the best either.

The pic is of me in the front of a group at a local criterium. Take a look and see what I am talking about.

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by r_mutt

one man's bed of nails is another man's sofa. not all pro's ride smaller head tubes and slammed 130mm stems, but there are more long and low fits in the peloton rather than not. they aren't sacrificing that much comfort if they are more flexible than the average person, they're bodies can take it.

look at the drop and reach! a 140 stem! hesjedal is a climber too.

http://velonews.competitor.com/files/20 ... IK9516.jpg" onclick="window.open(this.href);return false;

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by artray

I have a Ritchey 130 -17 slammed on my 54cm trek .
Im 6ft on a good day on a bad day 5 '11 and 3/4 .

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by Frankie - B

That bike has shallow bars. A small indicator he is not comfortable in the drops of standard bars with this long and low setup.

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artray wrote:I have a Ritchey 130 -17 slammed on my 54cm trek .
Im 6ft on a good day on a bad day 5 '11 and 3/4 .

That is why I posted what I did, seems weird.

Here is another pic
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by Pharmstrong

Hincapie wrote:
Pharmstrong wrote:6cm seems to be a lot of set back. I have virtually identical leg measurements to yours, and am riding 2.5cm set back on a 73.5° seat tube. Any reason why your seat is that far back?

If you look at the CC fit calculator recommendations in my post this doesn't appear to be a lot of setback.

Yeah, sorry I was measuring from the centre line of the seat tube. Measuring from the bottom bracket I too have ~6cm of setback.

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by Franklin

Hincapie wrote:
maggierose wrote:You claim a lack of road bike knowledge so how do you know you are on the incorrect frame size?

I've been to a few other bike shops to sort out my mechanical woes and they seem to agree.

Note that they have a very good reason to advise you to buy a new frame ;)

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by Hincapie

ultimobici wrote:The salesman should have told you to consider a different bike.

Bike or size? I don't think there are any bikes with dimensions recommended in the CC fit calculator.

ultimobici wrote:All too often I have had customers come in to buy a bike having narrowed down their choice in advance. They already can see themselves on the bike, irrespective of whether it will fit them. All they think there is left to do is sort out which size and model.

Admittedly I am guilty of this. I had the R3 picked out long before my purchase.

ultimobici wrote:Get a proper fit

I'm going to do a RETUL.

ultimobici wrote:Then look at whether you can get that to work on the R3. If you can't, sell it or return it to the shop as not fit for purpose.

If RETUL fit is way off, do you think I would have any recourse to the LBS?

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by Colonia

Play with saddle height and setback. 6cm is a considerable amount and is within the range recommended for your inseam by the old Genzling formulas. Other materials, like the old CONI manual, would suggest that a normal setback is anywhere from 3cm to 6cm, with 6cm being for very tall and long-legged riders.
Last edited by Colonia on Thu Mar 28, 2013 10:57 am, edited 1 time in total.

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by mrfish

IMHO you need to think through this in simple steps to get your position right within 1cm. After that it's fine tuning:

1) Does the saddle height give you:
- a small amount of knee bend at the bottom of the pedal stroke without over-compressing it at the top?
- no need to rock the hips to reach the bottom of the pedal stroke

2) Does the saddle setback give:
- Knee roughly over pedal spindle (note I don't believe in knee exactly over spindle. 2cm either way is fine, as shown by numerous Triathletes who seem to pedal OK).
- A position where you can pedal reasonably strongly then take your hands off the bars without falling forwards for a few seconds. Put the seat back and do core strenght exercises until you are balanced. This also ensures you don't put too much weight on your hands.

Note that the seat angle means you need to move the seat down to maintain the distance from the saddle to the bottom bracket if you move the saddle back. Rule of thumb is for 10mm back 3mm down.

3) NOW you can think about the bike length and height. It's hard to advise here without seeing you as flexibility, fatness, the size of your rib cage, length of arms and so on all vary. Basically though you won't go far wrong if you do the balance test as outlined in (2) and then position the handle bars so that the drops support your hands with a moderate bend of the elbows 1-2cm before you topple forwards. That gives a little bit of room for pedalling under normal conditions and allows you can get lower on descents by bending your elbows more. The hoods and bar tops will then give a higher position for climbing etc.

If the position is good typically you will be just about able to touch the bars with your knees if you really try, but they should not hit under normal conditions. The ideal frame will then put the bars in this position using 10-12cm long stem for best steering geometry.

Personally I am 175cm tall, very average size and flexibility, 79kg on a bad day and ride a 54cm frame with a 73cm saddle height, 6.2cm setback, 11cm stem, Ergosum bars and shimano 7900 shifters. Given you're a bit taller then me and only have a 1cm higher saddle, I would be surprised if you could not fit a 54cm frame with shorter bars and stem.

I would not compare yourself with the pro positions as they have a lot less upper body mass (both fat and lean), they pedal roughly 50% harder than I do and have stronger backs, so all things being equal they can get away with a lower and more stretched position without back pain.

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by elviento

Normally I don't recommend custom build unless one truly needs it, but here 75cm seat height w/ a 51.X top tube seems to be yelling custom.
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by MagnusH

Frankie - B wrote:That bike has shallow bars. A small indicator he is not comfortable in the drops of standard bars with this long and low setup.

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Or you could say that if you're comfortable in the drops of standard bars then your position in the hoods is too high. Since most riders use most time in the hoods it makes sense to make a fit to optimize position when riding in the hoods :noidea:

by Weenie

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by djconnel

HUMP DIESEL wrote:Here is another pic

I think the deal is you like riding with your arms bent, which makes sense since that's more comfortable, and you are still able to get a low-position without your handlebars forcing you down low.

I'm no fitting expert, but it seems in the end of the day, what matters is the back position and if you're comfortable.

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