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Quantitative performance specs for bikes(3 posts)

Quantitative performance specs for bikesContinental
Jan 20, 2003 12:59 PM
When selecting a bike I would like to have available 6 easily measured performance specifications. Currently, I only see 2 of these reported. I'd like to know: 1) Geometry--available. 2) Weight--available 3) Lateral stiffness--measured as bottom bracket deflection under various standardized loads applied perpendicular to the frame at the bottom bracket. 4) In-plane stiffness--measured as bottom bracket deflection under loads applied at the bottom bracket parallel to the frame. 5) Vibration dampening--measured by applying vibrations at the fork and rear dropouts and measurng the transmitted vibration at the seatpost. 6) Resonant frequency--measured by "ringing" the frame and measuring the frequency. It's not possible to reduce bicycle performance down to a few parameters, but these simple, standardized specifications would provide some concrete rational for evaluating bikes. Current bicycle performance discussions about stiffness and ride harshness are full of sound and fury. But maybe the marketers think that a bike is like a fine watch, where style, status, and perception are more important than performance.
it's out thereishmael
Jan 20, 2003 1:16 PM
I've seen a comparison of many models. Dont remember where I saw it; it was somewhere on the internet. It involved a lot of models and compared many of the specs you mentioned. I think it was done by some shop owner. Anyway, if you do some searching you'll probably find it.
Won't get you where you want to goKerry
Jan 20, 2003 4:34 PM
You may feel that these last 4 measurements will tell you what you want to know. In fact there have been repeated efforts to both make these measurements consistently AND to correlate them with actual bike performance. There's a lot of data out there, but there is no consensus on how to take the measurements so that they will be precise, accurate, and reproducible. Further, there is nothing solid that would allow you to use such information to predict frame performance. Lots of theories are put forth, but in fact you cannot use this information except to support your own prejudices.