Rear Derailleur Recommendation

[temporider]

I recently went from an 11/30 8 speed cassette to an 11/34 8 speed cassette on my Schwinn Tempo road bike. Up front is a triple with a 28 tooth small chainring. The bike is Shimano 105 equipped with components from the mid-90’s. However, I’m still running SIS down tube shifters that are set to friction mode. What’s a good derailleur to run with the bigger rear cog? The Shimano 105 on it now won’t clear the 34t cog.
Thanks!

 

[Cycleops]

You actually don't need a new derailleur if want to save money. Just add a Wolf Tooth to the 105 which drops it down so it will run your 34t.




This is Wolf Tooth Roadlink original but you can find cheaper copies on eBay.

Welcome to Cycle Chat.

 

[temporider]

Thanks - I actually ran across this a little while ago while looking at derailleurs. I’d never seen one before! I got one on order.

 

[Ajax Bay]

The OP doesn't say what his large chainring is but if 48t then he's asking his RD to perform well out of specification. The suggested wolftooth will solve the dinner plate 34t sprocket but asking it to wrap 43t ((48-28)+(34-11)) is a challenge. The solution is to size the chain length large to large plus 1" and accept that when straying into small/quite small there'll be some 'noise' as the chain rubs on the cage. Take this as a sign to shift up to the middle ring asap.

 

[temporider]

Actually, my large chainring is a 52t. I don’t like going into cross chain gear combinations. I stay on the three large gears out back when I’m on the small chainring for climbing and the four small gears when I run the large chainring on long descents. Lots of elevation change in my neck of the woods.

 

[raleighnut]

105 GS (long cage) should cope.

 

[Dogtrousers]

You're using friction shifters.

In very similar circumstances I used an Alivio (8 or 9 speed, can't remember) rear mech successfully. But my big sprocket on that bike is only 32 not 34. Mine works a treat. No need for a wolf tooth thingy.

The specs for the Shimano Alivio are capacity 45T; max low sprocket 36T which sound like they would meet your needs (required capacity 43T, required max sprocket 34).

https://bike.shimano.com/en-US/product/component/alivio-m3100/RD-M3100-SGS.html

 

[T4tomo]

if you really do need a 28-34 bottom gear then to get an 8 speed RD to "cope" with 47T difference, you probably need a long cage MTB RD.. Friction shifters gives you some freedom on not exactly matching shifter series, but I'm not sure modern 11 speed designed for narrow 11 spd chains will still work with 8 speed chain????

I think you either need to be searching ebay / retrobike for older Deore or STX / STX RC etc series long cage RD , or modern 9 speed stuff as suggested above by @Dogtrousers

 

[temporider]

All good comments - this is a great forum! I bought the wolf tooth on Amazon, so I can return it if it doesn’t work out. I’ll post up the results once I get it installed.

 

[temporider]

Dog Fang on the front and Wolf Tooth on the back. Took it out for a 15 mile test ride and everything works great. This will work for me.

 

[Chislenko]

28-34 should get you up Everest 😊

 

[ianrauk]

Too much excess oil on that chain. Give it a wipe through a rag.

 

[Ajax Bay]

Great phots! And I think your choice to install a dogfang mitigates the 'long' chain dropping risk. Please would you indulge me(us) by sharing images from the side of the chain on 1) large/large and 2) small/small.

 

[Cycleops]

Why is the QR lever on the drive side? 😧 Change it over.

 

[temporider]

Why is the QR lever on the drive side? 😧 Change it over.

What problems arise when the QR lever is on the drive side?