Citycoco "Harley" Stems

I got a company in town that rents these scooters. They are fun but are full of typical "Chinese quality problems." My least favorite is the stems, which wallow until loose and bottomed out. The fleet owner then tightens the bolts further until they strip, leaving me to:

1. Sand down the block to relieve the bottom-out
2. thru- drill and tap the bolt threads to a larger size

This works until the clamp wallows some more, or the clamp ears break off. I tried welding the clamps but the alloy is too poor.
I would like to design a better clamp, perhaps out of steel, but not if a product or improved design already exists. What do you have?

Are they threadless steerer tubes? If so, there's a lot of different threadless stems you can buy. You just need to make sure you get the right ID on the stem for both the bars and the steerer.

Also, it's possible the bearings and/or headset are bad (or installed wrong).

If they're threaded steerers, there's still lots of different quill-type stems available.


See the pages about those on the Sheldon Brown site for some good info.


http://www.sheldonbrown.com/headsets.html

Crazy looking units
https://youtu.be/ucOMxGQz_G4?t=49

Another technician tried using epoxy to repair a stem, so I sliced it off as shown. Look, it's full of casting defects! Also, not the upper right ear broke off.

The steerers are solid 25.4mm rods, threaded, with a machined flat spot. quite proprietary, or more similar to some scooter. Also shocked to find no retention or jam nut for the crown nut. At least 3/8 of these scooters have loosened crown nuts by over 3 turns. I applied nylon to the threads to lock the nuts.

Anyways, I'm still low on stems, since you can see one is now sliced in half, and two others have broken ears.

amberwolf said:

Are they threadless steerer tubes? If so, there's a lot of different threadless stems you can buy. You just need to make sure you get the right ID on the stem for both the bars and the steerer.

Also, it's possible the bearings and/or headset are bad (or installed wrong).

If they're threaded steerers, there's still lots of different quill-type stems available.


See the pages about those on the Sheldon Brown site for some good info.


http://www.sheldonbrown.com/headsets.html

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