Rear der ques. Campy 10s

[bikerboy337]

So I just finished pulling together my new caad with full record. When I'm in the big chainring, I can't get it to run smoothly on the largest three cogs, I know I won't be cross over with those gears, but on all my other bikes, all campy, those spin smooth. It seems like the chainline is off..the chain is running on the outside of the derailleur pulleys if that makes sense...any thoughts? I'll try to explain better tomorrow on a computer, thus is posted from my phone...all other shifting is flawless...is just really rough in the big big combo

Running cannondale branded sram red cranks, record rear d

Thanks

[maunahaole]

Look again at your campy instruction sheet. It tells you to recenter the pulleys under the 4th cog using the barrel adjuster after you get the big in front/small in back combination set. Also, make sure that you have the cable attached properly at the rear mech. It is very sensitive as to placement under the attachment point - it needs to sit in the groove, which is tiny.

[cmg]

set the screw on the derailluer for the larger cog. i believe it's the rearward screw on the front cover of the derailluer. check out the park tool directions, http://www.parktool.com/blog/repair-help/rear-derailler-adjustments-derailleur

[aoe]

+1 on the rear limit screw. A few turns should do it.

[CaptStash]

If noen of the above works, it could be an out of alignment derailleur hanger. That happened to me on a tri bike I was playing with. In that case I noticed the chain was doing funny things as it came off the big chainring.

CaptStash....

[bikerboy337]

I'm 99% certain its not the limit screw as when im in the small chainring, there are absolutely no issues, shifts thorugh all the gears smoothly... its just when i'm in the large chanring, large (26t) cog, the chain is entering the lower pulley at a steep angle and not sitting properly...


I'll fool with it again tonight and see if I can figure it out a bit more... its a brand new frame, so it should be the der. hanger...

[CaptStash]

Au contraire! Since it is a brand new frame it could very well be the der. hanger. At least that was the deal with my bike. The frame I was playing was literally new out of the box.

Saul aka CaptStash....

[Mike748]

...the chain is entering the lower pulley at a steep angle and not sitting properly...

I've had this happen with a Record RD that had a bit too much free play in the hanger pivot, allowing the derailleur to sit a little crooked. I added a shim under the pivot bolt head and that resolved it. Dave has posted about this, worth a search.

[CNY rider]

Is the chain too short?

[binxnyrwarrsoul]

Check the pulley cage. Even slightly "off" (bent,) can cause the chain to "jump" the pulley wheels, IME. Happens a bit more with medium and long cage, but is possible with short cages, also.

[kgbianchi]

Check the pulley, do they wobble?

[bikerboy337]

chain is spot on... that was my first thought last night, so i double checked that i set it up right (followed the park guide for big/big + inch)...

It certainly appears, after test riding a quick 15 today, that the pulleys wobble/derialleur is bent... when i'm in the big ring, large cog set up, the derailleur "bends" inward... which messes up the chain line, and the chain wont set on the pulleys... i'll try to fool with it tonight... basically i have 17 gears that i can use now... just the largest three cogs, when used with the large chainring, dont work... really strange...

my thought right now is the rear der. is bent or wont sit vertical, and "twists" a bit in the big/big combo...

i'll try to update to night if i can.. have to paint a room first (ugh)

[hockeybike]

Is the chain too short?

Just curious, how much harm is there in using a chain that's a hair too short (probably a link or so)? I transferred all the parts from my lynskey to the serotta a while ago and haven't had a chance to get a new chain on there, but the longer chainstays on the serotta have the RD STRETCHED in the big/big combo.

[dana_e]

if it is stretched too tight it can lock in the big / big

been there / done that

as long as it works and is not totally tight, you are good

the only time you should use the big/ big is by accident in the heat of the moment

[hockeybike]

if it is stretched too tight it can lock in the big / big

been there / done that

as long as it works and is not totally tight, you are good

the only time you should use the big/ big is by accident in the heat of the moment

Yeah, there's no locking (had that happen when hoping I could install a new bigger cassette on a friend's bike w/o more chain--whoops!). It runs, but the RD is stretched. Definitely not a combo there's any reason to be in.

[bikerboy337]

Ok, really spent some time on this, limit screws are all set, what's happening is that when I'm in the big chainring and I shift into one of the three largest cogs, the chain jumps off the lower derailleur pulley. It jumps off the pulley, to the outside. from what I can tell, everything else is dialed in, it just jumps outside of the pulley....

Any ideas? Could a bent der. Hanger do this? I'm at a loss

Thanks!

[oldpotatoe]

Ok, really spent some time on this, limit screws are all set, what's happening is that when I'm in the big chainring and I shift into one of the three largest cogs, the chain jumps off the lower derailleur pulley. It jumps off the pulley, to the outside. from what I can tell, everything else is dialed in, it just jumps outside of the pulley....

Any ideas? Could a bent der. Hanger do this? I'm at a loss

Thanks!

Either the der hanger is bent of the der cage is bent...bend it around. Pulleys in the der properly, top on top, etc? Inner der cage not upside down?

[Grant McLean]

In my humble opinion, the derailleur hanger should be checked on every bike.
If you're a cyclist, and care about how your bike performs, and spent a lot
of money on frames and parts, get the best out of them.

It seems to me, many mechanics (home & shop) just assume the hanger
"should" be straight because a frame is either new or expensive. Not true.

A major reason is people don't have the tool, and it used to cost a lot.
The park DAG-2 is like $50. If you ride with a few friends, buy one and
have them kick in $5 to check their own bikes. If you're also a mtn bike
rider, it's almost essential to own one in these days of replaceable hangers
that are as pliable as overcooked pasta.

-g

[Mark McM]

Ok, really spent some time on this, limit screws are all set, what's happening is that when I'm in the big chainring and I shift into one of the three largest cogs, the chain jumps off the lower derailleur pulley. It jumps off the pulley, to the outside. from what I can tell, everything else is dialed in, it just jumps outside of the pulley....


Jumping off the lower derailleur pulley is an odd one.

The last time I saw something like that, it was due to the chain being incorrectly threaded through the derailleur cage. Instead of being routed to the inside of one of the chain retention tabs on the cage, it was routed over the outside of the tab.

[bikerboy337]

It was a bent der. hanger... i guess one should never assume a new frame is set to go without a good once over... the LBS fixed it and everything shifts fine now...

Thanks all for the help/suggestions. I was hoping this was a home fix, but for a few bucks, my LBS fixed it.

Now I get to head out and ride the thing!