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retooling a 700c fork into a 650b

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retooling a 700c fork into a 650b

Old 08-23-13, 05:48 PM
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abdon
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retooling a 700c fork into a 650b

I want a 650b steel lugged cantilever fork, which are not that common at all. I was looking on ebay and found a vendor selling a bunch of 700c (allegedly) Fuji forks (http://www.ebay.com/itm/Fuji-700c-St...item58a304f841). I was wondering if it would be possible to heat it up, take it apart, cut it down to size, and rebraze it back along with canti studs. Has anybody done this? I wonder if there would be enough straight tubbing at the top for me to cut before the tapper comes to haunt me.
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Old 08-23-13, 05:53 PM
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Yeah, just don't.
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Old 08-23-13, 05:58 PM
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I dont think you should need to shorten the fork legs any. The OD of a wide 650b tire is pretty close to the OD of a narrow 700c tire. In any case, just start with a 700c fork that has the axle-crown measurement that you want. Adding (or moving) cantilever bosses on a steel fork is a fairly straitforward operation.

If you did need to drastically shorten a fork (like to fit a 571mm 650c wheel with narrow tires) then it makes more sense to cut off the end of the fork and add new dropouts, rather than to try to un-braze the fork legs from the crown.
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Old 08-24-13, 05:53 AM
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That's a bad idea. You might as well build the whole thing.

As Gray Jay said 650x42 = 700x23. A 370 mm a-t-c fork should fit a 650x42 with about 15 mm to spare of fender clearance.
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Old 08-24-13, 08:00 AM
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cantilevers are overrated. Long reach double pivot brakes are the way to go, the only problem being the quick release
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Old 08-24-13, 08:07 AM
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rebuilding a fork is a questionable idea at best. Lots of 700c to 650b conversions using the original fork.
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Old 08-24-13, 08:56 AM
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Cantilevers are fine. But require fork mods. Are you experienced at brazing? A fork is a very bad piece to have fail. So long reach brakes are a quicker/simpler solution.

Fork length, as noted above, doesn't need to modified.

How much do you trust these forks to be 1st quality, rather than something salvaged out of a dumpster?

If it was me, I'd consider getting a surly fork w/ a long reach brake.
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