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Proper Frame Sizing(5 posts)

Proper Frame SizingSquash
Jul 20, 2003 6:50 AM
I'm fairly new to road cycling, been doing it in the dirt for years, and am looking to expand my horizons so to speak. Not looking at racing, but would like to get into some touring. I've noticed that there is a vast difference between mountain bike and road bike sizing. I'm 6'5" with a 36" inseam and a 31" reach. I realize that there is allot more that goes into fitting a bike to the rider than what can be accomplished here. I am just looking to get a general idea of the frame size I should be looking at. I'm looking at making a purchase not sooner than next season so I have plenty of time to do my home work. Just looking for a little advice to get me started. Thanks.
re: Proper Frame Sizingcarcass
Jul 20, 2003 9:01 AM
For a 6'5" guy, the 36" inseam seems a bit short. I would double-check that measurement. If that is your true inseam, you would probably be a 61cm to 63cm center to top with a longish top-tube. A 61cm Lemond Zurich would probably be a good choice.
Words of advice, do not get talked into something smaller by a salesman.
re: Proper Frame SizingAlexx
Jul 20, 2003 9:47 AM
If you want a proper touring bike, Cannondale makes some of the best large touring frames, and despite what people say about the harsh ride of aluminum, it isn't bad when you get into 62cm-64cm sizes.
Frame sizing..coonass
Jul 20, 2003 2:48 PM
These sites will give you what you need to know; however a proper fit by an good LBS should the final step. http://psycle-therapy.great-ride.com/fit_links.htm
Ask some of the local road racers for their recommendations on where to get fitted.
There's a fair amount to itKerry Irons
Jul 20, 2003 5:46 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. There are no hard and fast rules, just general guidelines, when it comes to these things.

Just as important as your size is your flexibility. If you have a stiff lower back, you may not be able to lean over and stretch out as much. If you are very flexible, you may get away with a longer top tube, with the stem in a lower position. Over time on the bike, too, you may become more limber, or at least become accustomed to being lower and stretched out. So, your first 'real' bike may not be anything like what you will want 5 years from now.

Someone new to road riding is highly unlikely to find their ultimate position on the first go. As they become accustomed to the riding position and get some miles in, sometimes over several seasons, people often find their desired position changing. What was "stretched out" now feels OK, or what was "just right" now feels cramped. With time, if you are working on your position along with all your other riding stuff, seat position tends to rise, handlebars tend to be farther below the saddle, saddles tend to move rearward, and handlebars tend to be farther forward from the saddle. You simply cannot say "this is the right position for someone of your body dimensions" because there are too many variables and things that change with time. Get used to your position, and then occasionally make small changes: raise/lower your saddle, move your saddle forward/backward. Ride a while with the changes (a few 100 miles, anyway) and decide if it is better or worse. If it is better, keep moving in that direction. If it is worse, try moving the other direction. If you don't try, you won't find out, but it is a long term process, often taking years, to really dial in your position. And since your strength and flexibility are changing with time, it is reasonable that your position would need to change also.