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Bike geometry and set-up.....(6 posts)

Bike geometry and set-up.....Tim Field
Jul 18, 2002 12:23 AM
Being one of the unfortunate masses, I can't afford to buy a fully custom frame. Is there a web site that can tell you the idea top tube length, seat height etc. from your own body measurements? I'll then change my components to fit the bike. Don't get me wrong here I'm not far off a good fit but I want to make sure.

Many Thanks, Tim
re: Bike geometry and set-up.....bm
Jul 18, 2002 12:36 AM
wrenchscience.com
re: Bike geometry and set-up.....dirthead
Jul 18, 2002 3:38 AM
http://www.bsn.com/Cycling/ergobike.html
don't rely on body measurements...C-40
Jul 18, 2002 4:13 AM
Body measurements are very difficult to make accurately, with the exception of inseam. If you have a real bike that can be measured, it will be a much better indicator of adjustments that need to be made in TT length, frame size or seat tube angle.

The ideal saddle position cannot be determined by any amount of measuring. It must be determined through trial and error. Two riders could have exactly the same dimensions, but a spinner may ride with the saddle significantly further forward than someone who turns a lower cadence.

Even if you get a professional fitting, all the fitter can do is place your knee directly over the pedal as a start point, unless you can tell him a different position that works better. If this saddle location turns out to be 2cm from your optimum, the custom fitting isn't of much value.
excellent advise indeed.elviento
Jul 18, 2002 6:30 AM
Nothing beats actual trial and error. Body measurements are often inaccurate.

Unless you are of very unusual proportions, you can get fit properly by adjusting stem length, seatpost length, and fork spacers. Take myself for example, I can achieve exactly the same feet/hands/butt positions on 50-56 frames without looking or feeling too strange. In fact I once had to ride a friend's 58cm CT1, which felt just slightly stretched out. Many poeple get custom frames because they are just spoiled and/or rich.

The only case I find hard is when the rider sits VERY upright and needs very high bars and short toptube length. But if he is serious enough about the sport to shed $2k on a steel frame, then he might want to just ride a bit more and get used to a normal road bike riding position (I am not talking about super racy Michele Bartoli or Jacky Durand type position, but just the good old position with bars slightly lower than the saddle.) Dumping three grand on a Merlin XL is just overkill for something a city bike with slicks can handle.
excellent advise indeed.Tim Field
Jul 18, 2002 8:04 AM
Ok guys, you've convinced me to used to what I've got. I was just looking at the possitions from the Tour De France riders which all seemed pretty similar, that's the basis for the question. I may post again after a few months more riding.

Thanks, Tim