Bicycle Mechanics - Pin/cylinder in my sprocket prevents use of a chainguard
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12-16-07, 10:55 AM
I bought a new chainwheel/crank for my bike which uses hub gears. I removed the smallest of the three sprockets (the middle one is needed to keep the largest tight). The largest sprocket has a sort of metal cylinder (about 4mm diameter and 15mm length) in it, perpendicular to the plain of the sprocket, and pointing towards the crank arm. The cylinder is close to the edge of the sprocket and would therefore prevent me from having a chainguard over the sprocket. What is this cylinder (some might call it a pin)? It wont budge and is made from a different piece of metal than the rest of the sprocket.
12-16-07, 11:22 AM
It keeps the chain from dropping between the arm and the ring.
12-16-07, 11:24 AM
It serves two purposes, at least for other people. If you overshift it keeps the chain from becoming jammed between the chainring and the crank arm. It also indicates the proper orientation of the chainring so that the shifting aids will line up with the middle ring.
If it was my bike I'd chuck a cutting wheel into my Dremel tool and grind it off.
12-17-07, 07:30 AM
Unfortunately I'm a student in a foreign country and my rotary tool is at home. Maybe I can smash it off with a rock... :D - I'll see if a friend can help me out, or maybe even my landlord.
12-17-07, 07:47 AM
You can usually take/break it off with pliers. Or you can modify the chain guard
12-22-07, 09:11 AM
It came right out with pliers and a bit of wiggling. I was scared off bending the sprocket but it hardly takes any force at all. Thanks for the advice :)
You can also get single-speed length chainring bolts so you can get rid of the unused chainring.
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