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proper bike size(5 posts)

proper bike sizejfd141
Jun 25, 2002 8:44 AM
Hey guys,
As a long time mountain biker I'm trying to make the switch to road biking. People tell me different things about proper size and I'm a little confused. I'm 6 feet tall, and rode a 19 inch mountain bike. A local bike shop tried to fit me on a 60cm but I think they were trying to pull a fast one on me cause that was the only size they had left in the bike I was interested...when I test rode it my arms were way too stretched out trying to hold the handle bars.

After further research I've concluded that I'm mostly likely a 56 or 58 cm size but I can't decide which one. I'm leaning towards a 56 cm. Also, I've heard bigger bikes are better for long rides, while smaller ones are better for this true? In other words, are there any advantages to slightly smaller or slightly larger frames?

- John -
re: proper bike sizeDave Hickey
Jun 25, 2002 9:00 AM
I suggest going to a shop that will fit you properly. A 56 to 58 sounds closer to your needs but remember manufacters measure their bikes differently. Some manufacters measure center of the BB to center of the top tube(ctc). Others measure center BB to the top of the top tube(ctt). In other words, a 56cm frame can be the same size as a 58cm if the 56cm is measured ctc and the 58 is measured ctt.
More links and commentsKerry
Jun 25, 2002 5:24 PM

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.
Link to sizing helpdirthead
Jun 25, 2002 9:03 AM
I went through the same process not long ago. The best advice I can give you about sizing a bike is not to take the advice of a salesman. They are there to sell you a bike, not necessarily the best bike for you. I know there are exceptions to this, but I think the vast majority of salesman in bike shops have NO experience in professionally sizing someone to a specific bike. Each bike will fit differently. The various manufacturers use different geometries and different measuring systems, so a 56cm bike from Trek will not fit like a 56cm bike from Colnago.

The following link helped me make my sizing decision

The sizing calculator on this site will use your body proportions and the specific frame manufacturers geometry to give you the bet fit. It will also calculate the optimum stem length, bar width, and saddle height.

My first bike purchasing experience was a Cannondale Caad4 road bike, which was fit to my by a salesman at a sporting goods store. The bike was a little big. The test ride felt fine, but was very short, about 5 minutes. On longer rides, I would get very uncomfortable. Hands would go numb, along with other private parts, and back pain. I decided to buy another bike, Merckx Team SC, and had it professionally fit at Cycles BiKyle, His fit matched the fit I calculated on the site I linked above exactly. He used the same body measurements for his sizing calculations. I would definitely recommend purchasing from them if you are going for a high end bike. I have never been more comfortable on a bike. I feel like I could ride all day.

Hope this helps!

Ride On!!!!!!!!
Great link...thanks!!! (nm)kapalua
Jun 25, 2002 10:00 AM