ExpertTools

I just bought a 5 year old S-Works Roubaix. Equipped with Sram Red 10sp. There is a little road rash on the rear derailleur, and I can only get it to index properly on about 2/3rds of the cassette. I have a Park derailleur alignment gauge, and it’s way off. The hanger was also loose. Anyway, I ordered a new hanger, but I have two questions:

If it’s still out of wack with the new hanger, and I would assume a carbon frame can not bend, is it possible the rear dropout is bent? And if so, can this be straightened?

Also, any ideas where to obtain the two tiny hex head screws that hold the dropout to the frame? One of mine the hex is is a little damaged.

Andrew R Stewart 

Don't assume that the bike industry tolerances will insure a plug and play replacement hanger, expect the need to check it's alignment and the likely tweaking to get such really straight.


We align (I mean cold set, I mean bend them) replaceable hangers all the time, both new and old. Andy

ExpertTools

With a carbon frame bike, do you pull the hanger off the bike and bend it in a vise, or just use a derailleur alignment tool while it’s mounted to the bike? I’m hesitant to put too much pressure on the frame.

Andrew R Stewart 

You treat a carbon frame just like any other. Place the rear wheel in the drop outs and secure the axle tight. It will hold the drop out in place and prevent any bending force from distorting the drop out. Only the portion of the hanger below the drop out/axle will bend.


It's very good that you ask about this as doing this type of repair improperly can lead to far greater problems. Andy

Crankycrank

Mount the hanger and tighten bolts properly then align the hanger as Andrew R Stewart mentioned. Don't worry too much about hurting the frame. The aluminum hanger will bend much easier than the rest of the frame. And also as he mentioned always check a new hanger as they don't always bolt up perfectly aligned in the frame.

ExpertTools

Thanks for the advice guys.

woodcraft

The replacement hanger should come with screws.

Kontact

How about aligning the current hanger?


Most aluminum derailleur hangers are tempered to the hardness of cheddar.

ExpertTools

This seemed pretty stiff. And was way out of whack. Also, given that the screws were loose for who knows how long from the previous owner, I'd bet the holes could be a little enlarged. I already ordered a new hanger.

sch

Hangers are untreated aluminum, deliberately soft so as to bend and spare
the much more expensive frame. OTOH repeated bending soft aluminum
will tend to make the aluminum to crack. As a side comment the markup
on hangers must be pretty phenomenal but it is a low turnover business.

Kontact

I would tighten the screws properly, remount the wheel and align your current hanger. If that works, ride it and save the replacement for the next time you bugger up your current hanger. The amount of force on the hanger that comes from normal use of the derailleur is tiny - if the hanger survives being bent into alignment, it will survive use.

fietsbob

By Now don't Carbon frames sensibly use replaceable Aluminum derailleur hangers?

once you have it installed, then have it tweaked into alignment at the Pro Bike shop ...

hope you ordered 2..







...

Kontact

What do you think the OP is asking about?