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Wheelbuilding Tip No. 11 - Stuck Cogs

May 23, 2011 2 Comments

[Note: this is #11 of a series of 20]

Don't let stuck cogs interfere with wheel rebuilds.

When rear wheels need new rims and/or spokes, stuck cogs (or freewheels or cassettes) can prevent introducing new spokes. Gears sit near the drive side hub flange and you can't get spokes in or out when they're in place.

With multi-speed hubs and coaster brakes, the solution is to disassemble the hub. Remove the axle and all guts. Out comes the driver with the cog. The empty hub shell can easily be laced with a new rim. Now, reassemble the hub and finish the build. Reassembled, the hub will rotate accurately and you can true your wheel.

 

Interfering cog removed.

 

For stuck fixed and freeewheel-type gears, the problem is solved another way. Best is to remove all gears while the previous wheel is still built. It's easy to remove cogs when the rim is still laced up and can be used to hold the hub still.

If, however, your rim has been removed too early, you can reattach it for the sake of cog removal. This requires a dummy rim and spokes for one side of your hub. The spokes must be "dog leg" shape rather than traditional elbows. "Dog leg" spokes are rare these days but any length will do. If you have none, bend some up for the occasion.

 

"Dog leg" end on the right.

 

Dog leg spokes can be inserted from the hub end because they have no enlarged head, just the "Z" shaped bend. Insert them into the flange nearest the stuck gear. Attach all of them to the rim with nipples. Twist the rim so all the spokes are in the cog removing direction. Voila, the cog or freewheel can be removed with standard tools.

Don't let stuck cogs or gears prevent your rebuild!


2 Responses

Nate Gill
Nate Gill

November 02, 2021

Just last night, I faced the problem of removing a stuck fixed gear cog from a hub that had already been cut loose from it's rim. I was lucky in the the hub was aluminum, and the cog steel. Aluminum shrinks more than steel in the cold, so I put it in the freezer for an hou, clamped the hub into a vise longways, with a piece of wood on each end. Took a steel punch, a hammer, and by hammering

Steve Barner
Steve Barner

November 02, 2021

If you’re lucky enough to be working with a large-flange hub, and you have a frewheel still installed after the customer cut the spokes, you can often get access to the spoke holes by disassembling the frewheel body. You can leave the inner threaded part on the hub until you get the wheel built and then remove the remaining part of the frewheel and re-assemble the freewheel.

If you have a small-flange hub, and you don’t care about the freewheel, you can disassemble the freewheel body as above and carefully grind almost through it with a die-grinder. Don’t try to grind all the way through. Get close on both sides and then break it off by striking CCW with a cold chisel. If you do it right, the body will crack on the side where struck, and unscrew easily. It would likely be quicker to use headless spokes, but this is an alternative if none are available.

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