djangophat

Hi and thanks, in advance for any insight/resource/help you can provide.

After having two bike mechanics attempt to 'fix' and 'adjust' the stock GT-150 derailer on my '71 Schwinn Varsity it still will not shift properly. Not looking to salvage it or try something tricky to get it to work, just want to find a good/newer system to upgrade. Should I also be considering newer shifters? Hopefully, a system that won't require too much trouble to install.

Thanks again for any help!

sonatageek

Since your setup is friction shifting (as opposed to index) just about any derailleur will work. If you have a bike coop there are a bunch of Suntour derailleurs from the 70's which would be a great upgrade and replacement. If you decide to go new, even a Shimano Tourney (which is very low in their product line up) which would also be big improvement to your old GT 150.

oddjob2

I hate to admit, but even this would be an upgrade. You'll need an RD with a claw hanger. Replace your cable/housing too.

Sun Race SR 515 Short Cage Rear Derailleur | eBay

djangophat

Sounds like some good options. I looked up the Shimano parts on ebay and found some pretty good deals. Any thoughts on what to do about the shifters? Thanks for your help, Sonatageek!

Dave Cutter

Yeah almost any of the newer derailleurs should work. The shifters (levers) shouldn't matter much since you'll still be old school ten speed friction. I'd buy new cables, cable housings, and a chain too. Actually.... I'd replace the chain and cables (in that order) first before I replaced the derailleur.

djangophat

Thanks Dave, good call. Thankfully, I do have a new chain but will replace the cables and cable housing.

Metacortex

I concur with all of the advice given above, but I wanted to set the record straight on the derailleur designations. The Schwinn GT-150 was a rebadged Shimano Thunderbird *front* derailleur that was used on some 10-speed "World" and Schwinn bikes from '71 through '73. The rear derailleurs used on the Varsity at that time were either the "Schwinn Approved" rear derailleur, which was a rebranded Huret Allvit with no number designation, or a GT-100, which was a unique model expressly made for Schwinn by Shimano, with no comparable Shimano branded version.

John E

Caveat -- SunTour derailleurs require more cable wrap than the original Huret unit did. (This is also why they have a lighter feel and do not break cables as often.) When I built my wife's Peugeot with TwinStiks and my old SunTour V-GT, I had to file the front plate's tab that goes into the backing plate a bit to provide enough shift lever travel. No big deal -- easy modification.

When I had a Varsity, I installed an ultra-6 speed freewheel and clamp-on SunTour downtube shifters, which of course required a shim.