cccorlew

Has anyone stretched the limits of eTaps wifi rear derailer? It's spec'd at a 32 tooth max, but I'd love to go 34 or maybe even 36.
Sinner or winner? Brilliant or ill advised? Catches on fire and burns? No problem?

RoadLight

Hi cccorlew,

There is no single answer because it depends on your bike's frame and, most importantly, its rear derailleur hanger. Some bike frames and hangers will allow you to use a 36t cog with a short-length rear derailleur cage, let alone a medium-length like the SRAM eTap Wifi. Unless you know someone with the same bike frame and hanger who has already tried to do what you want, then you probably won't know if it's possible until you try it, yourself.

Here are some things to be aware of: First, you'll probably have to unscrew the "B" adjustment screw on the rear derailleur quite far in order to fit a bigger cog. You may even need to unscrew it all the way (or remove it). What you need to do is make sure the largest cog clears the top derailleur pulley by a minimum of 2 mm when shifted to it. If it doesn't, then the chain will lack adequate clearance between them.

Second, letting the B screw so far out will cause the rear derailleur to rotate clockwise toward the rear of the bike. Plus, you'll probably need to use a longer chain. These two factors will combine to create a longer variation in required chain length between the extremes of your gear combinations. The length of the rear derailleur cage may not be able to maintain as much tension at the small end and this can lead to more chain slap and a greater possibility for the chain slipping off.

Lot's of cyclists are able to successfully use a larger-than-rated cog with their rear derailleur and the way you'll know if that includes you and how much bigger you can actually go is probably by trial and error.

Lastly, there are some hanger adapters that effectively lengthen your hanger but they are mostly for Shimano rear derailleurs. Most of these adapters are not recommended for SRAM systems so bear that in mind when you hear about them.

Kind regards, RoadLight

TimothyH

For what it's worth, I'm using a SRAM PG-1170 11-36 cassette with Shimano 6870 GS rear derailleur on a Ninter RLT 9 RDO.

Not sure if it has any bearing on the original question but just putting it out there.


-Tim-

springs

I use a PG-1170 11-36 with my etap wifli. No problems. 2011 Cervelo RS, stock hanger.

cccorlew

Thanks so much for your carefully considered and detailed answer. Info I can use!

Thanks to Springs as well.