Hello all,

Currently I have an old touring Trek that was handed down to my by my dad that is about 35 years old. I'm pretty sure its rear derailleur is the original. I was changing the tubes on my back tire and while putting it back on, I somehow snapped the rear derailleur in half.

My question is, what would be a compatible replacement? The current one was a SunTour Cyclone Mark-II (3500).

Thanks!

You can find that exact derailleur on Ebay, sometimes NOS. But they seem to run expensive -$35-125 or so. I'd get a different derailler. There are plenty that will work: others here will know better which ones. I suspect that that previous version (which is just called a Cyclone) will work just as well. The Mark II was different in that it was more aerodynamic looking. There are two different lengths of the jockey-wheel cages. You probably want to match whatever you have.

If you find a replacement and want to do the work yourself, be advised that, given the force required to break a derailler, your hanger (the little tab of metal that the derailler fastens to) may be bent and if so will require straightening.

Last, not to be a jerk, but if you snapped a derailler in half while changing a tube, would it be a good idea to take this to the bike shop for a repair?

Last (this time I mean it), can you post a pic of what broke?

"Touring" bike suggests long cage. You're not going to like the price of a used cyclone "GT" long cage. Friction shifting I'll assume. I'd look at "Deore LX" for half the price and all the functionality.




Shimano Deore M591 9 SPD Rear Derailleur > Components > Drivetrain > Mountain Rear Derailleurs | Jenson USA

Shimano Deore M591 is a real problem solver. Works well with anything from 5 to 9 gears in the back. But, with friction shifters just about any decent RD will work. I like the old Shimano Sora stuff. Back when they still made it out of polished alloy.

+1 this. Just be sure whatever derailleur you choose wraps enough chain to handle your gear range. And most modern derailleurs incorporate both SunTour's slant pantograph and Shimano's sprung upper pivot, so performance is likely to be as good or better than the old Cyclone, even from a relatively low-end modern derailleur.