Bicycle Mechanics - Replacing Broken Axle?
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04-17-11, 11:57 AM
I thought I was becoming a pretty good bike mechanic. I routinely buy abused vintage bikes and rebuild them from the frame up. But, this is the first time I’ve had to replace a broken axle and it has me confounded. The axle set is out of a “Sunshine Gyro-Master” 40 spoke 5spd FW hub that came off a ’79 Miyata touring bike. It appears to measure 134mm end-to-end. I could buy a replacement axle set from “Loose Screw” or others; except, it seems that the cone needs to match the bearing size and I don’t know how to determine that. The bearings are larger than the BB sized ones I’m used to. They appear slightly smaller than the quarter inch ones used in a bottom bracket with 9 per side. I tried to use an axle off a Shimano 105 hub, but to my surprise, the threads were different.
Any help would be greatly appreciated.
Is there something wrong with the cones? If not, I'd just bring a cone or a locknut to a well-stocked bike store and scrounge around until I find an axle with the correct thread. If it's too long trimming it a little is no big deal.
Do your best to salvage the cones, so you have a perfect match for the bearing. Then it's only a matter of matching the axle thread and length.
First the thread, you need to measure and match, or visit the LBS with a cone and match it that way. Here's a link to the Wheels manufacturing page (http://wheelsmfg.com/content/view/469/32/) listing available axles. Odd are you have a 9.5x26tpi though it could be anything.
As for the length it's usually somewhere between 8 and 12mm longer than the over locknut width, to match the width of the dropouts it's intended for. Low end bikes have thinner dropouts so 134mm for a 126mm axle makes sense, but you can buy a 137mm and grind the ends if needed.
04-17-11, 10:27 PM
I was wrong about the threading. It is standard Shimano or whatever. I'll scrounge for a replacement axle, but one of the cones is shot. I'm assuming the cone needs to match the bearing size? If I have to order one, how do I determine the size?
04-19-11, 05:49 PM
Most Shimano and Sunshine, Sanshin and Suntiour hubs used axles with the same threads and replacements are available. However, 134mm axles are for 120mm wide drop outs, and the replacements made for Suntour or Shimano hubs from Wheels Mfg are 137 mm long for 126mm wide dropouts.
I find that a lot of axles on old wheels with freewheels, especially six speeds, are bent if not broken, and I have been wondering whether to grind or cut them down a few mms.
It is also possible that the hub was overhauled and whoever did it used the wrong size bearings which would explain the ground up cones, and perhaps the broken axle
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