Spacers on crankset without info
08-01-20 | 06:04 AM
#1
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Spacers on crankset without info
Hey,
I just got a crankset from China and wondering how many spacers I need and what distribution. Since the crank is from China im not surprised there isn't any information on that whatsoever. Got a 68mm BSA30 and the crank can also be used for 73mm shells so I definitly need spacers. Is there any way to measure it and compared it to something similar or is it more like try and error?
I just got a crankset from China and wondering how many spacers I need and what distribution. Since the crank is from China im not surprised there isn't any information on that whatsoever. Got a 68mm BSA30 and the crank can also be used for 73mm shells so I definitly need spacers. Is there any way to measure it and compared it to something similar or is it more like try and error?
08-01-20 | 06:52 AM
#2
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Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
Trial and error would be my first thought. This would only take 15 minutes if all was at hand. Between chain ring clearance with the frame and chain line measurements it should be easy to figure out the best arrangement. Do this "dry" then reassemble with proper lube for the final install. Andy
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AndrewRStewart
AndrewRStewart
08-01-20 | 08:59 AM
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Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970
You don’t care about chainring clearance from the frame, unless the chainstay is interfering with the inner chainring.
What you want to do is center the crank to the middle of the cassette.
Depending on the crank and the bike the quick and dirty answer is 2.5mm of spacers, but if the crank is designed for a 135mm dropout then it might be more. The other issue is the FD and how far it will reach to be able to shift to the outer chainring. In that case it is a trial and error and a compromise.
John
What you want to do is center the crank to the middle of the cassette.
Depending on the crank and the bike the quick and dirty answer is 2.5mm of spacers, but if the crank is designed for a 135mm dropout then it might be more. The other issue is the FD and how far it will reach to be able to shift to the outer chainring. In that case it is a trial and error and a compromise.
John
08-01-20 | 09:10 AM
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Ok thanks sounds logical. I have a 135mm dropout but didn't knew that cranks can be or should(?) be desgined for that. Seems like I have to get some extra width spacers for trying out. My 2.5mm spacers variations didn't gave me any config in wich the chain didnt drop or make bad sounds.
Oh and is there a easy way to notice if you have to many spacers? I noticed when I go for the rough torque spec. my BB builds up resistance.
Oh and is there a easy way to notice if you have to many spacers? I noticed when I go for the rough torque spec. my BB builds up resistance.
