Sunday, February 07, 2010

Bike fit.

I have just bought a new road frame. Yes, i only got the cannondale caad 8 a few months ago, but i knew at the time that it was very much a 'starter' road bike, and that if i liked riding the road, i'd want something perhaps a little tidier.

So a Spooky skeletor is coming my way. Anodised black, size 54 with compact geometry and an aluminium frame. Should be sweet. It's well priced and has garnered good reviews in terms of the ride quality. Initially i'll swap parts over, but there may need to be one or two changes. The tourery triple will be removed: i spend most of the time in the big ring, and no time so far in the granny, so a 53 on a standard double will be welcome. I'm going to use a shimano 105 - it is not high zoot, but it is very much more pleasing on the eye than the truvativ i have at present.

The wheels, at present will be an old dt 340 to dt R1.1, with the rear an as-yet-to be-decided-on build, most likely with the new version of the R1.1 - the R415. At present, the choice is between a DT 340, or a shimano 105 for less cash. We'll see.

The rest is getting swapped over from the cannondale. Maybe a different stem, and most certainly a different seat post. It's a shame that it wont be blacked out, but as time goes by i'll work on it. These are not mine, but they are close to what i'm going to aim for.

A few folk have commented on the fact that my road frame seems small for my 5'11" height. Yes and no. I tried out a few bikes, and different sized frames, prior to getting the canondale. As im getting more used to road riding, my ability to stretch out is improving, and i'm happier with the lower bars. Just took some time to get used to. Initially, i removed the stock anatomic bars in favour of some short reach and drop compact bars. Recently i have moved to a slightly longer stem, in order to get the front rear balance better, and the flats further away for seated climbing. The saddle was initially rammed forward, and i was considering an inline post, but gradually it has come back by about 4mm. The top tube on the spooky is 4mm shorter, and i will prefer the saddle being further back relative to the bottom bracket i think, so this is all good.

But again - its a small frame no?

I had heard about the bike fit system available on the Competitive Cyclist website through some chat on a bike forum. You need to be careful using a bike fit system, as individuals are never entirely equivalent. Fit is best done by either informed trial and error, or by a professional. On a mountain bike, i'm pretty clear about what fits. For road riding, where so much time is spent sat down, fit is both more important and new to me. However, i got to a point with the canondale where i was pretty certain what reach i needed. The other aspects of road riding fit that are particularly important are balance of weight between the wheels and steering weight distribution. Too short a stem or too high bars (or rarely funky geometry of the fork/head angle) can leave the front wheel grasping for traction on fast downhills. A short wheel base with good front centre will help the bikes handling and paying attention to reach and saddle set back will allow the legs and glutes to help the core in keeping the trunk low for wind resistance avoidance. Of course, you also want to avoid a numb wee man if you can.

So: as long as the frame is designed well, and your fit avoids overly pushed back/forward bars and saddle, it should be good.

My Measurements

Inseam 82 cm
Trunk 66 cm
Forearm 34 cm
Arm 60 cm
Thigh 60 cm
Lower Leg 55 cm
Sternal Notch 151 cm
Total Body Height 180 cm

Plugging my measurements into the Competitive Cyclist fit calculator was interesting, as it confirmed what trial and error had suggested to me - despite my height, i will fit best on 54cm top tube skeletor. It also suggests that at least according to some folk, my current ride position is reasonable.

The Competitive Fit

Seat tube range c-c 53.1 - 53.6
Seat tube range c-t 54.7 - 55.2
Top tube length 53.8 - 54.2
Stem Length 10.9 - 11.5
BB-Saddle Position 73.4 - 75.4
Saddle-Handlebar 51.8 - 52.4
Saddle Setback 4.4 - 4.8

The Eddy Fit

Seat tube range c-c 54.3 - 54.8
Seat tube range c-t 55.9 - 56.4
Top tube length 53.8 - 54.2
Stem Length 9.8 - 10.4
BB-Saddle Position 72.6 - 74.6
Saddle-Handlebar 52.6 - 53.2
Saddle Setback 5.6 - 6.0

The French Fit

Seat tube range c-c 56.0 - 56.5
Seat tube range c-t 57.6 - 58.1
Top tube length 55.0 - 55.4
Stem Length 10.0 - 10.6
BB-Saddle Position 70.9 - 72.9
Saddle-Handlebar5 4.3 - 54.9
Saddle Setback 5.1 - 5.5

Here, the Eddy fit (as in Merckx) is a slightly old school fit, higher front end and further back. The French fit is more of a touring type set up - higher again at the bar, and further back.

I suppose i'm probably aiming for a racing type set up for what i want to do on the bike - high output, mid-length rides with lots of climbing.

Once its built up and i've put a few hundred miles on it, we'll see if all that tape measure work paid off.

If you want to give it a bash, the fit calculator is here.


Buck said...

I'm sure the skinny tires and multi speeds look good on you.

Much like the 30" of snow in my yard doesn't look so good on me.

Road bike good - Facebook bad

give Trina a hug for us.

Anonymous said...

The reach and stem length on that calculator seems a bit short. I'd wager your saddle tip to handlebar center measurement should be more like 57-59. 75 sounds good for the saddle height though.


Anonymous said...

What Lance said.

Without wanting to upset Mickey - that's a lot of money to drop on an alu frame. Still, as long as you feel "alternative"...

dRjON said...

thanks for advice mickey. the current road bike has a 55 saddle tip to mid bar....not sure on the drop. its a longish saddle (san marco zoncolan) and i hope to move the saddle back relative to bb a little too (currently it could be fitted with an inline post, but i will use a set back post) so may well end up getting near the saddle-bar you suggest. i will of course be reporting back!