Fit Calculator??

[Roy E. Munson]

In a moment of complete boredom this morning, I surfed onto www.competitivecyclist.com (http://www.competitivecyclist.com) and entered my measurements into the fit calculator to see what would be returned as recomended sizing. Either I have some serious physical problems, or that thing needs an overhaul. Now my measurements may have been off a tiny bit, but the results were crazy!

I must add that I don't believe in these type tools. The only way I see to get a bike to fit is to ride it and try various stem, seatpost, bar, etc combo's.

[theoldman]

Last summer I did an experiment with the fit calculator that you mentioned. We ran the numbers with three different riders that have been riding for 30+ years. Then we measured their existing bike set up that had been dialed in through experimentation/trial and error.

The result,

All three had their bikes set up very close to the numbers output from the fit calculator. I was surprised.

A sample size of three can not make for a factual conclusion, but it does illustrate that it has some merit.

But I do not believe that any computer tool (at least not yet) can fit a human form to a bike. But it does provide a tool in helping someone find a starting point in the fit process.

Serotta has the fitting process right (in my opinion). Their fit cycle, coupled with trained personnel makes fitting a bike more predicatable and more likely to get the size close to what a rider needs.

Most non-Serotta LBS do not get the bike fit correct. The experimentation with the fit calculator was coupled with visits to various bike stores. I was interesetd to see what size various shops would fit me on for a new ride. The sizing was all over the map. Some had me on a 52 others on a 58 from the same manufacturer. At least the fit caclulator had me on a bike size that was close to what I had 'evolved' to.

The overall experiment included many fit sessions, on line calculators, serotta fit cycles and multiple riders. It also included some standard brands and custom frames. The conclusion was the following:

1) most seasoned riders probably have their bikes 'configured' to what works best for them.

2) Some computer models are a good indicator of what the bike should be initially set at.

3) Not all computer models make sense.

4) The Serotta fit methodoligy is probably the best on the market.

5) The average LBS (read: many/most non serotta trained) cannot be trusted with fit. This is especially true if they do not have all frame sizes in stock.

6) If you are buying a non-serotta frame it really helps to understand geometry and trig (actually it helps all the time!), . These math skills can help in understand how the frame will fit. Most bike employees probably do not fully appreciate how a changing bike geometry will effect fit. And less fully grasp the math.

7) Buyer beware! Not all shops have the skills or time to fit a bike correctly.

[Dr. Doofus]

Mr. D. Says:

I pity the fool who uses that to set up their bike.

Mr. D.'s saddle is higher, but everything else is pretty close...Doc rides 1cm less setback, but his TT is 1cm longer...and the doc does ride a longer stem than that thing says...not as long as Senor J, but then Kelly built the doc's bike with a slightly longer f-c, and if the Doc went' eye-tal-yain he'd run a 57 top and a 140 stem or thereabouts....

That calculator came up with very close numbers...but it ain't a machine, its a very very good fitter...and them's hard to find unless you have 10 pounds of twizzlers ready, you have a stash of CONI manuals and beer nearby, or you are good pals with Giancarlo F.....

[Roy E. Munson]

Out of curiousity, I went back and remeasured and entered some new values ( I wiffed on the first inseam #) and the numbers weren't TOO far off what I currently have set up. I agree with Doofus though, "I pity the fool who uses that to set up their bike."

[David Berry]

My take on fit calculators and formulas is that they are a start to get you in the ballpark. Yes, everyone's proportions are different, but at least you have a somewhat more scientific start than just the eyeball.

But here I think is where the size cycle is such a great invention. You can plug the numbers from the formula into the size cycle, and see how it feels. And you can ask questions like what if my stem was 10 mm shorter/longer. What if I change the size of this or that. And you can actually see how it feels.

I personally wouldn't ever buy a bike just on formulas or calculators. I think they also suffer because different people have different riding styles. But perhaps they have use at the beginning of the fit process to get an idea of where to start.

David

[bostondrunk]

Roy, ya old fart, don't mess up the fit I helped you with. Do you still have the handlebars 3 inches higher than your seat?? Keep it that way!

[Roy E. Munson]

bostondrunk,

Still cold up there in Canada? You know I'd never trust you to fit my bike, you drunken canuck. Still out buying frames through mailorder, sight unseesn, then having to sell them because they don't fit? I told you that you were asking for trouble, but you wouldn't listen.