Classic & Vintage - Help with Topline crank

Hi,

I have acquired a Topline crank, and am looking for info. There doesn't appear to be a model name, but I can't find pictures of any different topline cranks either. Does anyone have any general info about this crank?

Second, the rivet that holds the arm to the spider is loose. It will wiggle back and forth about a mm. This can't be normal, but I also don't see what could cause this to be loose or how to fix it. Any ideas?

Thanks in advance186777186778

Hi Fadetoblack6902 -
Sorry I can't be of much help on identification. I would have a little concern though, that thing could let loose, and frankly I haven't met a swaged crank yet that was worth the risk.
My advice is to hang this one on your garage wall.

I can't help you with the model but the rivet would seem to be primarily for alignment during the swaging operation, to ensure the top spider arm is exactly opposite the crankarm. The swage itself should lock the ring in place and carry the torque. However, if you're really concerned, pull or dirill out the rivet and install a self-tapping screw.

Isn't that an aluminum spider?

Yes its an aluminum spider

Lookee here....a concise description of the product line of now defunct company.

I've seen several in use, including my own. Never seen the failures that others speak of. I like mine a lot. I think they're not the most rugged but for the daytripping many of us do I think it's fine. Including the T-mar remedy for yours.

http://www.bikepro.com/products/cranks/topline.html

J

Awesome, that link helps a ton. Thanks! Do you know if the play in the rivet is normal?

I think not. Likely some real mashing over time or some other abrupt or extended "abuse". Imagine this "delicate" looking crank in use on an off road bike. A lot of them went that route.

Can you tell which side - rotationally speaking - the rivet is deformed on? The configuration of the deformation? Might be a clue.

If there's play between arm and spider then the swaging must be loose. I have second thoughts about how effective and long lasting the repair will be. Only you can tell. Caution is the word.

J



Awesome, that link helps a ton. Thanks! Do you know if the play in the rivet is normal?

AFAIK that spider is not swaged, but threaded to the crankarm, and the SS rivet just is a "safety" to keep it from unwinding...if the rivet's loose I'd just pry it out and clean the hole then re-install with GREEN LocTite. If the spider is loose on the arm, that's another issue. I'd consider some LocTite BLUE on those threads just as a good measure.

^^^^

That's interesting. I never thought it through before. Just took a look at mine and the typical evidence of swaging on the inside of the arm/spider intersection is not there. Threaded makes sense.......and is probably good news for the OP.

J

Threaded huh? that's great news if I can find a way to pry the rivet out. There is zero gap between the rivet and the spider. I can't even begin to fit my smallest screwdriver under it. any ideas?

If you can't or don't want to drill out the rivet........here's a wild idea: drive the threaded arm into a most forward possible position and have a tig welder lay a bead all around it on the back side. :eek: If necessary then dress with a dremel. I've seen some pretty dadblame well controlled bead lines by good welders.

I've got a friend who came out of the nuclear reactor construction industry. He can weld a set of cuffs on a mosquito's ankles. Litespeed is also in my town and has some pretty good graduates.

There must be others.

This is a "disposable" crank at this point. You can't mess it up any more, practically speaking. Have some fun. Think artfully and maybe put it back in service.

If you can't or don't want to drill out the rivet........here's a wild idea: drive the threaded arm into a most forward possible position and have a tig welder lay a bead all around it on the back side. :eek: If necessary then dress with a dremel. I've seen some pretty dadblame well controlled bead lines by good welders.

I've got a friend who came out of the nuclear reactor construction industry. He can weld a set of cuffs on a mosquito's ankles. Litespeed is also in my town and has some pretty good graduates.

There must be others.

This is a "disposable" crank at this point. You can't mess it up any more, practically speaking. Have some fun. Think artfully and maybe put it back in service.

Whether you can find a good welder or not, you have to heat treat aluminum after welding for it to have any strength, I would suggest a different route - although I don't have any specific suggestions. They are beautiful cranks though, so hopefully you can save them, I love the set I have.