Join Date: Nov 2006
Bikes: 05 Giant TCR 0; 83 Colnago Saronni; 81 San Rensho Katana Super Export track bike, #A116-56; 97 GT Zaskar
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good BB height for short cranks?
I've been looking for a bike for my wife, who is pretty short at about 4'10", but fairly normal proportionally.. and even though we're in Taiwan and ther are plenty of smaller frames around, none ft her in terms of a decent top tube standover height. even the small wheel offerings from Giant like an OCR W in XXS size are too tall in the top tube, which is just ridiculous seeing how low the seats are on them.
i finally realised the reason: almost every bike i saw with 650c wheels, in months of casual looking, has had 170mm or in one case, 175mm cranks installed! of course, this means a really high BB is needed, almost at the level of the axle, and even then there is minimal safe pedal clearence. and as well, how on earth is she meant to turn a 175mm crank, when that's longer than I use on my race bike?
So, i think we might be investing in a custom frame, perhaps with a more reasonable 150mm crank set up (stronglights).
Any one out there with some idea of a useful BB height for such a frame, given that we will be looking at building a short top tube (not very long arms either), and we must have a decent top tube standover height. I am thinking a compact frame with sloping top tube will help. there is a guy who makes Ti frames for reasonable prices here, so we may go that way...
we don't want a mixte type bike, which have the wrong geometry, but a capable road bike light enough for her to pedal uphill and sit on for several hours... and one that's not built from a large crank, large wheel perspective.