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What size frame would be a good starting point?(3 posts)

What size frame would be a good starting point?NonClimber
Mar 18, 2002 3:02 PM
I'm in going to buy my first road bike and I was wondering if some of you could give me some help with frame sizing. I'm 6 ft tall with a 90 cm leg. If I understand sizing correctly I should be on a 58cm c-c or 60cm c-t frame. I was in a shop today to look at some bikes, and asked about Trek frames. The guy said I should be on a 58cm 5200 (didn't have any in stock), but from what was said in another post Treks are "small" for their size. So should I be looking at a 60cm? I'm also looking at Cannondale and Colnago bikes so are these also "sized small" or is it just Trek?
Please refer to the Idiot's Guide to Bike FitPack Meat
Mar 18, 2002 3:15 PM
This can be found on this site at
http://www.roadbikereview.com/Discussionscrx.aspx

Look at the sidebar.
Do the mathKerry
Mar 18, 2002 4:52 PM
http://www.bsn.com/cycling/ergobike.html
http://www.coloradocyclist.com/BikeFit/index.cfm
http://www.sheldonbrown.com/harart-frames.html
http://www.rivendellbicycles.com/frameinfo/Frame_Sizing.htm
http://www.peterwhitecycles.com/fitting.htm

For adjusting the fit of the bike, there are roughly five starting points:

1. Seat height (top of saddle to center of pedal axle) at 108-110% of inseam.
2. Saddle parallel to ground.
3. Saddle fore/aft adjusted so that a plumb bob from the bony protrusion just below the kneecap passes through the pedal axle when the cranks are horizontal. This is known as KOPS (Knee Over Pedal Spindle)
4. Front hub axle obscured by the handlebars when riding in your "regular" position (drops, hoods, or tops).
5. Top of handlebars 1 to 4.5+ inches below the top of the saddle depending on your flexibility and size.

These are all starting points for "average" proportioned people, and many folks like to move away from these starting points as they learn what makes them more comfortable, powerful, or efficient. You want to get the fit of the frame as close as you can, then do minor adjustments with the stem, seat post, saddle position, etc.

A lot of this is personal comfort, and we all tend to adapt to a given position over time. For example, a given stem length may be right for you, but it may feel long at first. I use the "handle bar obscures the front hub" rule for my fit, but others claim better position (for them) with the hub in front of or behind the bar. I'm 6' tall and ride with 11.5 cm drop from saddle to bar, probably more than most people would like but fine for me. Some are suggesting zero drop from saddle to bars - it's about comfort, efficiency, and aerodynamics. The ERGOBIKE calculator is pretty good, but it is not infallible. I would suggest riding some miles (over 100 total, and over 500 would be better) and see if you adapt to the position. If you continue to feel the bars are too low, go for a riser stem. There are no hard and fast rules, just general guidelines, when it comes to these things.