Position differences on compact vs. traditional frames?



davidd86

New Member
Nov 29, 2004
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Is there anything about a compact frame that is inherently supposed to position the rider differently? I ask because I recently swapped out a Team Miyata steel frame, which was just a traditional horizontal top tube unit, for a used Giant TCR, which is a compact frame. I just put all the components in exactly the same place, starting at the BB and measuring from there. The TCR took a slightly shorter stem to do it but the riding positions are absolutely identical. If you closed your eyes it would be extremely difficult to tell which bike you were on. Obviously there's much more seatpost showing on the Giant. It's the same position I've had as a Cat 3 and Masters rider for several years.

(I have just made up a marked stick to show the saddle height, the setback -- i.e. on my setup the saddle is dead horizontal and the nose of the saddle is exactly 3.5" aft of the BB spindle -- the reach and drop to the bars, and lastly the angle of the hoods. Works great and takes only a couple of minutes to do - you just use the marked stick and a long carpenter's level -- although I usually have to fine tune the saddle height by a couple of mm on the first ride.)

I ask because I rode by a very Euro, somewhat poseur-ish bike shop to buy a new inner tube and I was talking to the guy and he said the position should be different on the compact frame. That makes no sense at all to me. But I keep reading it in this BBS as well. Why is a compact frame, in and of itself, any different for the rider than a traditional one? I thought it was just a matter of saving a bit of weight by having slightly less metal.
 
davidd86 said:
Is there anything about a compact frame that is inherently supposed to position the rider differently? I ask because I recently swapped out a Team Miyata steel frame, which was just a traditional horizontal top tube unit, for a used Giant TCR, which is a compact frame. I just put all the components in exactly the same place, starting at the BB and measuring from there. The TCR took a slightly shorter stem to do it but the riding positions are absolutely identical. If you closed your eyes it would be extremely difficult to tell which bike you were on. Obviously there's much more seatpost showing on the Giant. It's the same position I've had as a Cat 3 and Masters rider for several years.

(I have just made up a marked stick to show the saddle height, the setback -- i.e. on my setup the saddle is dead horizontal and the nose of the saddle is exactly 3.5" aft of the BB spindle -- the reach and drop to the bars, and lastly the angle of the hoods. Works great and takes only a couple of minutes to do - you just use the marked stick and a long carpenter's level -- although I usually have to fine tune the saddle height by a couple of mm on the first ride.)

I ask because I rode by a very Euro, somewhat poseur-ish bike shop to buy a new inner tube and I was talking to the guy and he said the position should be different on the compact frame. That makes no sense at all to me. But I keep reading it in this BBS as well. Why is a compact frame, in and of itself, any different for the rider than a traditional one? I thought it was just a matter of saving a bit of weight by having slightly less metal.
I've rode both types myself and never really noticed any difference apart from the standover height. Some say that because of the smaller frame size, compacts are stiffer. Not too sure about that.
 
I'm with you, when measured in relation to the BB, all things being equal, fit is the same. Weight savings are probably very minimal due to an increased seat post as you noted. I believe that compact geometry allows the manufacturer to produce more fit options, using components like stems and posts, with fewer sizes, and therefore less cost to them. But we could both be wrong, I look forward to the science guys who will undoubtedly post up soon.
 
CDAKIAHONDA said:
But we could both be wrong,
No, you're right. While it's possible to get the seat down lower relative to the bars on a compact, it isn't necessary. The weight savings are negligible, and there's no reason why a compact geometry is inherently stiffer. The reasons for the trend are mostly aesthetics. While the manufacturers can get away with fewer sizes, there are some high end custom builders who offer it as an option.
 
davidd86 said:
Is there anything about a compact frame that is inherently supposed to position the rider differently? I ask because I recently swapped out a Team Miyata steel frame, which was just a traditional horizontal top tube unit, for a used Giant TCR, which is a compact frame. I just put all the components in exactly the same place, starting at the BB and measuring from there. The TCR took a slightly shorter stem to do it but the riding positions are absolutely identical. If you closed your eyes it would be extremely difficult to tell which bike you were on. Obviously there's much more seatpost showing on the Giant. It's the same position I've had as a Cat 3 and Masters rider for several years.

(I have just made up a marked stick to show the saddle height, the setback -- i.e. on my setup the saddle is dead horizontal and the nose of the saddle is exactly 3.5" aft of the BB spindle -- the reach and drop to the bars, and lastly the angle of the hoods. Works great and takes only a couple of minutes to do - you just use the marked stick and a long carpenter's level -- although I usually have to fine tune the saddle height by a couple of mm on the first ride.)

I ask because I rode by a very Euro, somewhat poseur-ish bike shop to buy a new inner tube and I was talking to the guy and he said the position should be different on the compact frame. That makes no sense at all to me. But I keep reading it in this BBS as well. Why is a compact frame, in and of itself, any different for the rider than a traditional one? I thought it was just a matter of saving a bit of weight by having slightly less metal.
Your common sense and mine agree that position is defined by the relationship of the rider to the BB/pedals, saddle, and stem. If those are identical with two different frame shapes, the rider will feel no difference in position. Theoretically the compact frame may be lighter, and a bit stiffer, and the compact frame will allow a lower standover height, but the correct fit relationships are unchanged. Any other thoughts are nonsense.