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i'm converting an old schwinn traveler in to a fixie. i plan on buying new rims with a flip flop hub, and with fixed/free sides. i installed a new bottom bracket, but when i started thinking about putting on new cranks with a new chain ring, and aligning that with the rear cog, i got stuck. the spindle on the bottom bracket i was told is too long (shimano un53, xl 118, 68 eb, bc 1.37x24 - i think the 118 is too big?)
How do i determine what size spindle to get with what cranks? I've looked at sheldon brown's site a bunch, he's the one who told me the spindle is too long, but i can't figure out how to get things straight.
any suggestions? thank you ~ j.
How do i determine what size spindle to get with what cranks? I've looked at sheldon brown's site a bunch, he's the one who told me the spindle is too long, but i can't figure out how to get things straight.
any suggestions? thank you ~ j.
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Oregon
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Re: building a fixed gear and confused
Thu, January 17, 2008 - 12:49 PMI have no suggestions for your problem. I will suggest bypassing the whole flip-flop thing, and just going for the fixed hub. You will NEVER used the free-wheel once you are competent with the fixed gear...which occurs in about a week. Maybe two.
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Re: building a fixed gear and confused
Thu, January 17, 2008 - 6:15 PMIf you can, take it back to the shop and swap for one with a 113 or even 111 spindle. -
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Re: building a fixed gear and confused
Thu, January 17, 2008 - 6:28 PMput the chainriing on the inner side of the dbl crank.
if that don't work, swap out the Bb for a 68x110/113 BB.
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Re: building a fixed gear and confused
Sat, February 9, 2008 - 7:19 PMThis is a difficult task without knowledge of the mechanic's mathematical equation!
First.. do yourself a favor and do the homework. Regardless of what gear you're running on what rear end spacing.. do this.
Decide what your rear end spacing will be.. in mm's. Are you spacing your rear end to the hub.. or vice versa?
Because I'll assume that your hub is 120mm spaced - half that number = 60. This is centerline.
Now measure the hub.. from the outside of the driveside locker (cone/nut) to the center of the toothys on the cog.
This will be a measurement I'll call "instep", and it will be subtracted from your centerline. (60)
On track spec gear, the instep will usually be about 17mm for a 43mm chainline.
Does the math make sense?
It should, and even better if working with strange gear involving rearends and hubs that are not spec to 120mm.
Now that you know where your cog sits on the chainline.. now it's time to take a look at the front.
Measure where your chainring sits by very carefully placing a piece of tape along the center of the downtube..
AS CENTER AS POSSIBLE!!
Then, simply measure from that line to the center of the chainring toothys.
Based on the previous measurement, however mm's you may be off as your chainring is concerned will be remedied..
By a bottombracket that is whatever amount of mm's you are off in either direction..
And I may add that running a chainring on the inside or outside of the crank may be a consideration..
When chainlining with a road or mountain crank.
As I'm a mechanic by day, and fixrider by night.. I hope that my formulae is of some help.
Especially given the project you've undertaken.. a project which I've "fixed" myself with some difficulty.
If it's the one I'm thinking of it used a 1pc BMX "snakecrank".. which made things difficult. Maybe not..
Good luck,
Moon
