Bikeguide.org - Bike maintenance for BMX'ers
The Street => The Bike Shop => Topic started by: Travis Bickle on December 23, 2017, 11:59:02 AM
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Hello,
I'm trying to figure out the wheelbase of two different frames to compare because the geometries are much different. After looking online for over an hour, I cannot seem to figure out how to calculate the overall wheelbase to any frame. Could someone help me figure out the wheelbases to each of these frames but also how to calculate frame wheelbase for future use?
Thanks
Frame one:
TT: 20.5
CS: 13.625
BB: 11.7
ST: 8.75
SA: 71°
HT: 74.5°
Frame two:
TT: 20.5
CS: 13.625
BB: 11.8
ST: 8.5
SA: 71°
HT: 75°
Assume Odyssey R32 fork
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I think you will like this site http://www.bikegeo.net
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Thanks for the link! It's very helpful however, I'm wondering how accurate it is, because based on the calculations it is saying there is only 1mm difference between an S&M ATF and a Credence MOD frame as far as wheelbase goes, assuming the same CS length. I always thought .5° in headtube angle was .15" (3.81mm). Granted, the MOD BB is .1" lower.
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I'm curious why you'd be concerned about the front half of the wheel base? I've never thought about it much. The headtube angle and bottom bracket height differences I'd notice much more than the minimal difference in the distance between the bottom bracket and front axle. But I guess it's all relative. I don't think it would be much at all though, I think frames with a 69 seat tube usually ran about 1/4" smaller than a 71 seat tube frame, 21.25" 69* frame had the same wheelbase but larger front end than 21" 71* frame. So half a degree on on the headtube would only be like 1/16" difference, right? haha I doubt that's anything you'd notice.
Edit: 1/16" is 1.5mm so maybe my guess is right haha
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I think frames with a 69 seat tube usually ran about 1/4" smaller than a 71 seat tube frame, 21.25" 69* frame had the same wheelbase but larger front end than 21" 71* frame.
It would only feel longer when you're sitting down though. The BB and HT would be in the same relative place on a 21" 71 degree frame as a 21.25" 69 degree frame. Remember how they sold the Tierra with measured and effective TT lengths listed? I always thought changing the ST angle was the dumbest thing.
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I think frames with a 69 seat tube usually ran about 1/4" smaller than a 71 seat tube frame, 21.25" 69* frame had the same wheelbase but larger front end than 21" 71* frame.
It would only feel longer when you're sitting down though. The BB and HT would be in the same relative place on a 21" 71 degree frame as a 21.25" 69 degree frame. Remember how they sold the Tierra with measured and effective TT lengths listed? I always thought changing the ST angle was the dumbest thing.
The BB and HT thing is exactly what I said. But I'd way rather ride a 21.25 69* seattube than a 21" 71* seattube. The extra room up front is definitly noticeable, for me atleast, bar spins and tables feel better.