Old 05-10-08, 10:09 PM
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andychang
Chicago needs more hills.
 
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Standover Height

I will offer my limited experience and knowledge to this issue. Depending on what type of geometry a road bike has (traditional, traditional/italian, compact, etc. etc.) standover height will be partly determined by the length of the seat tube, the angle of the virtual versus actual top tube, and the resulting "hypotenuse" of the downtube. In order to obtain an aggressive or plush feel, manufacturers must optimize the fit of the bike against the dimensions of the main triangle. For example, if somehow a bike had a 42 c-t seat tube with a 61 c-c virtual due to some type of severe case of "long torso and tiny assed legs", it would be a very awkward looking (and probably slower handling) bike.

Standover height can be useful if you want to take advantage of new seatpost technologies. It's been found through independent testing that the length of crank arm that an individual uses has very nominal effects on the efficiency of power transfer from your legs. In other words, the human leg would never create enough revolution-al force to warrant an extension of even 2.5mm per crank arm. Of course, we know that some people will always swear by a certain length for their own personal reasons.

However, more SO combined with 167.5mm cranks or even 165.0 cranks WILL allow you to use newer seatposts that boast the best in technology. If the bottom bracket remains stationary, leg extension static with the only variable being crank arm length, shorter cranks would yield a higher seating position than longer cranks would. A shorter c-t measurement (or in our case more SO height) will also yield the same result.

As a side note: When I built up my Tarmac Pro, it was quickly evident that I would not be able to fully appreciate the S-Works carbon seatpost with Zertz inserts because honest to goodness, the actual insert was BARELY above the collar level. I opted instead for just a nicer aluminum seatpost. Had I had more S.O, it's possible I would have been able to use the S-works post.

I guess that if you were REALLY cramped in the inseam and you were barreling along at 25mph and all of a sudden fell RIGHT onto the top tube that could be not as optimal for the family jewels. Although, I do suspect that even if you had 1 - 2 inches of SO and you were involved in the same nut-cracking accident, unless you fell off and your shoes had super powers and somehow you did not skid, crash, etc. - the boys would be equally as injured.

On my Gary Fisher Piranha, I opted to get the XS frame at 13" rather than the small at 15" which I could have ridden. I think when riding on the trails I just feel more comfortable and somehow more "in control" if I have a smaller frame. Most of my mountain accidents have come primarily on slower technical portions rather than blistering fast open ones, so when I know that I am losing control doing a log roll or windy singletrack, I can quickly unclip, have that extra clearance, and save myself from falling on logs, jagged rocks, heaps of dirt, etc.

As for cyclocross? No clue yet. I believe that all of your comments have merit. When I am doing training rides on the Conquest Pro, I will put 700*25cc's on. Also, I HIGHLY suspect (and I think I am right by looking at pictures of the smaller models) is that Redline does the SO measurement based on the "average", or midpoint of the top tube to the ground. Because it is listed at 44 by 51, I think that delta(L) between the virtual and actual top tube lengths would require an aggressively sloped top tube; it's possible that the SO height adjacent to the seat tube would be less than the 736mm that's listed on the website. I'll be able to know for sure next week when the bike arrives.
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