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Discussion Starter · #1 ·
In the big ring and any of the 3 largest cogs my bike down shifts 2-3 gears when I back pedal------any other gear combo is fine

The derailer hanger was bent (had a minor crash) so I replaced that and then replaced the rerailer itself but all to no avial. I have swapped the wheel with another and still no improvement.

I also checked the chain and its length and that seems fine

I have replaced the rings as used a 52 instead if a 50---it is a triple but it was doing htis before so it is hard to think the bigger ring is at fault

Any ideas ???? It is a Carbon Roubaix---the dropouts may be bent but they look fine--bike
 

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Maybe the jockeys are goobed up?
Cable housing issue?
Don't backpedal? :)

I put on a new chain and had the same problem. Turns out it was too long. Double check the chain length is the same as the previous one.
 

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rlemmer said:
In the big ring and any of the 3 largest cogs my bike down shifts 2-3 gears when I back pedal------any other gear combo is fine

I have replaced the rings as used a 52 instead if a 50---it is a triple but it was doing htis before so it is hard to think the bigger ring is at fault

Any ideas ???? It is a Carbon Roubaix---the dropouts may be bent but they look fine--bike
This is to be expected - the chain angle for a triple large chainring to largest cogs is too acute, and there is nothing to keep the chain on the cog. Don't backpedal in those combinations.
 

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Discussion Starter · #4 ·
Well--my wifes triple does not do this nor did mine when new---nor do those in the shop---so while I agree the angle is pretty acute this does not seem normal.

Tongiht I swapped cassettes just in case and no improvement. And the chain is very snug--almost want to add a link to see if that helps.

cheers
 

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Depends if your wife has the exact same bike, with the same components, wheels, and chainline.

Things like all affect the ability to backpedal in extreme crosschain situations.

I have a mountain bike that does exactly what you describe.
 

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The problem could be a number of factors, some which have alread been mentioned and too many to mention. Either have a friend who knows bikes look it over with you or bring it to a mechanic to look at it.

BTW, just because you replaced the rear derailer hanger doesn't mean it is straight. Many of them come out of alignment new. Put an alignment hanger tool on it and make sure it is straight. If you don't have one, which most people don't, bring it to a shop so the can check it out. This is the first thing that needs to be right before anything else can be done.

After they make sure it is straight, tell them about your problem and see how they can help you.

1) Hanger Straight
2) Chain is good
3) Chain line
4) Pully Wheels
5) Sticky free hub

BTW, why are you back pedaling. Keep your feet moving forward....it will get you where you want to go faster.
 

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rlemmer said:
Well--my wifes triple does not do this nor did mine when new---nor do those in the shop---so while I agree the angle is pretty acute this does not seem normal.

Tongiht I swapped cassettes just in case and no improvement. And the chain is very snug--almost want to add a link to see if that helps.

cheers
Kerry Irons is right: What keeps your chain in place when you pedal forward? That's right, a derailleur! it's what positions the chain on the cogs. When you pedal backwards, the derailleur isn't on the top to stop the chain from moving. My bike does this if I cross-chain as well.
The best advice was already suggested: Don't pedal backwards and you won't have this issue.
 

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First of all, as others have noted, you shouldn't be using the big ring up front with the one or two largest in the rear at all. Likewise you shouldn't use the smallest front ring with the two smallest on the rear. Either way you end up with a cross-chain situation that's more likely to cause problems.

Other than that, there are a number of possibilities. Yes, too long a chain is one. Another is the adjustment of the B screw on the rear derailleur, if there's insufficient tension on the rear derailleur, it might wind up too close to the cassette. Too large gears on the rear, with a short cage derailleur, might cause problems, too. Even how well the chain is oiled and whether or not it's clean might also have an effect.

I think the first thing I'd check, though, is the alignment of the rear derailleur mount. I check them on every bike I build and it's surprising how many are out of alignment right from new... some pretty seriously. It's easy to check and correct, but you need a special tool that costs more than $50 so I'd suggest you take the bike to a good, local bike shop. They can check and adjust it, if needed, pretty quickly. If that's not the issue, they might spot something else.
 
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