I have an 80's Trek 1000. I recently replaced the chain after waiting too long and had to replace the cassette too. Everything seems okay now, except that if I push very hard in the highest gear (largest front and smallest rear), I can get the chain to pop off to the outside onto the crank arm. I am doing this while riding very slowly and pressing hard on my front foot while braking. I thought this would be a good way to test that the chain would stay without it happening unexpectedly while riding in traffic. My local shop thought the chainring still had life to it when I got the chain. Am I wasting my time testing it this way? Would I be able to force the chain off like this even with new parts? The derailleur was about 5mm above the chainring teeth so I lowered it to between 2 and 3mm. I also adjusted the limit screws. I can still make the chain come off under force.
Please note that the shortest teeth seen in the photos are at the bottom of the chainring when I am in the position when I am applying a lot of torque to test it.
by dim-witt
11 Comments
Those teeth are cooked, time to replace the chainring too
https://preview.redd.it/iqwupc451nwg1.png?width=444&format=png&auto=webp&s=1e495b42d33aaf39f51a975e974a1a0a371f8477
This is what your chain ring looks like. I’ll just leave you to ponder that 😀
That chainring looks cooked
Shark’s tooth appearance means it’s worn out.
Uhhhh, for real? Can’t imagine what is happening.
you have zero teeth on the chainring buddy, amazing the chain stays on at all 😭😭😂😂
Thanks, all. I’m glad there’s an easy solution to this. I’m confused why the shop thought it looked good still. Maybe they just glanced at the part that looks the best and missed the worst section. I also thought that if I still have flat tops the to teeth that means they aren’t that old?
LBS said the chain rings had some life left because it’s too difficult to find replacements but they still wanted to sell you a chain and some service cost. The reality is it’s cooked.
It’s not unsolvable. If you start searching the interweb you find one somewhere. Failing that you would definitely get one at a local swap meet if you have one. There will be NOS somewhere.
New everything. Chainrings, chain, cassette. Make sure you have a good look at your derailleur.
You also need a new chainring.
Replace your entire drivetrain!! If you just replace one it will be ruined by the other worn out drivetrain pieces in turn still do the exact same fall of or skipping. Replace chainrings, cassette & chain. Also look at the wear on your rear derailleur pulleys. ⚙️🔧