[chudson0616]

Hey all,

So i just recently purchased a specialized secture at a local bike shop for cheap. Everything seems to work properly except for some reason while in the biggest casette ring, when pedaling backwards the chain skips off of the ring and binds up the derailleur. I know its not really a big deal just dont pedal backwards but was curious if anyone had any input on it either maybe being a worn casette or the derailleur being out of adjustment. Any info will be appreciated. Thanks

Chris

 

[jamesh75]

Take it back to the bike shop where you bought it and ask them to adjust the rear derailler. Or if you're mechanically inclined, watch some youtube videos and adjust it yourself.

 

[PJ352]

Hey all,

So i just recently purchased a specialized secture at a local bike shop for cheap. Everything seems to work properly except for some reason while in the biggest casette ring, when pedaling backwards the chain skips off of the ring and binds up the derailleur. I know its not really a big deal just dont pedal backwards but was curious if anyone had any input on it either maybe being a worn casette or the derailleur being out of adjustment. Any info will be appreciated. Thanks

Chris

You've answered your own question. Don't pedal backwards.

I've been doing my own wrenching for about 25 years, keep my bike in tune and it does the same thing.

Not all exhibit this 'trait', but it's generally caused by a less than straight chain line. Cross chaining (outer ring, inner cog) would be an extreme example.

Anyway, go ride (and enjoy) your bike. It's fine.

 

[TricrossRich]

Hey all,

So i just recently purchased a specialized secture at a local bike shop for cheap. Everything seems to work properly except for some reason while in the biggest casette ring, when pedaling backwards the chain skips off of the ring and binds up the derailleur. I know its not really a big deal just dont pedal backwards but was curious if anyone had any input on it either maybe being a worn casette or the derailleur being out of adjustment. Any info will be appreciated. Thanks

Chris

You've answered your own question. Don't pedal backwards.

I've been doing my own wrenching for about 25 years, keep my bike in tune and it does the same thing.

Not all exhibit this 'trait', but it's generally caused by a less than straight chain line. Cross chaining (outer ring, inner cog) would be an extreme example.

Anyway, go ride (and enjoy) your bike. It's fine.

This is NOT the right answer...

A properly tuned rear derailleur should not do this. There could be a couple of reasons. It could be that the chain is excessive worn and no amount of RD tuning will get it right, but being that the bike is new, I doubt this is the issue. My guess is that the RD is just slightly out of adjustment, probably the cable stretched a bit if the bike sat for a while in the shop, or if the bike was literally just built before you got it, your first couple of rides could have stretched it a little and put it slightly our of adjustment. If you don't feel comfortable making any adjustments, take it back to your shop and they should straighten it out in about 20 seconds. if you feel comfortable, check out some Youtube videos... my guess is, you need to turn the barrel adjuster on the back of the rear derailleur maybe 1/8th to 1/4 turn counter clockwise. Doing so, should move the pulleys on the RD, directly under that last cog. Right now, they're not quite under, so the chain jumps back down a gear when you backpedal.

 

[PJ352]

This is NOT the right answer...

You're right that there could be several reason for a chain dropping to a lower cog when pedaling backwards, but fact is, in practice it doesn't matter.

Think about it. Pedaling backwards, the chain is moving backwards across the cog, then thru the RD pulleys with little tension on it. So the likelihood of it seeking a straighter path increases.

Conversely, during 'normal' pedaling, the chain is tensioned, runs bottom up thru the RD pulleys and then the cog.

If the OP's drivetrain otherwise shifts and runs smoothly, all is well with the adjustments.

Just as an aside, if you review Shimano's tech docs, nowhere will you find steps where the chain is run backwards thru a RD for proper setup.

It's not broke, so no need to 'fix' it.

 

[TricrossRich]

You're right that there could be several reason for a chain dropping to a lower cog when pedaling backwards, but fact is, in practice it doesn't matter.

Think about it. Pedaling backwards, the chain is moving backwards across the cog, then thru the RD pulleys with little tension on it. So the likelihood of it seeking a straighter path increases.

Conversely, during 'normal' pedaling, the chain is tensioned, runs bottom up thru the RD pulleys and then the cog.

If the OP's drivetrain otherwise shifts and runs smoothly, all is well with the adjustments.

Just as an aside, if you review Shimano's tech docs, nowhere will you find steps where the chain is run backwards thru a RD for proper setup.

It's not broke, so no need to 'fix' it.

When the chain is put on a cog, it should stay on that cog, whether being pedaled forward or backward. The fact that its kicking back down on backpedal and subsequently binding is a sign that it is not set up correctly. If you want to keep riding your bikes like that, that's fine, but clearly the OP doesn't and he's asking how to fix it.

 

[PJ352]

When the chain is put on a cog, it should stay on that cog, whether being pedaled forward or backward. The fact that its kicking back down on backpedal and subsequently binding is a sign that it is not set up correctly. If you want to keep riding your bikes like that, that's fine, but clearly the OP doesn't and he's asking how to fix it.

I don't see where the OP is saying he doesn't want to ride his bike, nor where he's asking how to fix it. He's merely asking opinions.

No mention on Shimano's tech docs I see, but that aside and as I've offered, a RD is not designed to do what you're describing. It's as simple as that. That (in some instances) pedaling backwards doesn't drop the chain to the lower cog is happenstance, nothing more.

OP, I'm confident in my posts and stand by them. If it will give you some peace of mind (assuming you trust their judgement), ask the owner/ operator of the shop or the wrench there for a third opinion. Either way, if this is the only problem exhibited by the drivetrain, your bike is fine.

 

[taodemon]

No mention on Shimano's tech docs I see, but that aside and as I've offered, a RD is not designed to do what you're describing. It's as simple as that. That (in some instances) pedaling backwards doesn't drop the chain to the lower cog is happenstance, nothing more.

Not that I attempt pedaling backwards often while riding but I have done it and I've never had the chain drop a gear or things bind up as a result.

 

[PJ352]

Not that I attempt pedaling backwards often while riding but I have done it and I've never had the chain drop a gear or things bind up as a result.

Here's an example that (I think) illustrates my point.

My bike has an SRAM chain on an otherwise Shimano 105 (5600) drivetrain. Initial installation of the chain (for whatever reason) required a slight cable adjustment to fine tune rear shifting.

Pedaling backwards resulted in the chain dropping to the lower cog (when in the inner cog/ outer ring). Now, after maybe a few hundred miles, that no longer occurs - no further adjustments made.

So, was something 'wrong' on initial installation/ adjustment and it magically 'fixed' itself? I don't think so. As I posted earlier, it's happenstance - pedaling backwards doesn't follow a normal chain line (exacerbated when cross chaining) and isn't how RD's are designed.

 

[PJ352]

On a separate but related topic, I noticed in your OP you were asking about a worn cassette. Worn cassette cogs generally cause a serviceable (read, good) chain to skip. Your bike doesn't seem to exhibit this, so unless both chain and cassette are worn, no reason to think the cassette is worn.

However, to avoid future problems, it would be good to periodically measure for chain wear. Place a 12 inch ruler along the bottom chain run, align the 0 mark with the center of a chain rivet. Note where the 12 inch mark aligns on a rivet. If the center or the rivet is at 12 inches the chain is new or nearly new.

Off by less than 1/16" and the chain is showing some wear but is still serviceable. If it misses the 12 inch mark by more than 1/16" the chain requires replacement, but the rear cogs should be ok. As mentioned, worn cogs on a new chain will typically cause the chain to jump or skip in the worn out cogs.

FWIW I replace my chain at the 1/16" mark.

 

[TricrossRich]

Here's an example that (I think) illustrates my point.

My bike has an SRAM chain on an otherwise Shimano 105 (5600) drivetrain. Initial installation of the chain (for whatever reason) required a slight cable adjustment to fine tune rear shifting.

Pedaling backwards resulted in the chain dropping to the lower cog (when in the inner cog/ outer ring). Now, after maybe a few hundred miles, that no longer occurs - no further adjustments made.

So, was something 'wrong' on initial installation/ adjustment and it magically 'fixed' itself? I don't think so. As I posted earlier, it's happenstance - pedaling backwards doesn't follow a normal chain line (exacerbated when cross chaining) and isn't how RD's are designed.

It didn't fix it self... it was not correctly adjusted at first and then due to cable stretch or some other cable tension change, you rode it into adjustment... give it another few hundred miles and it will probably start skipping again.

 

[PJ352]

It didn't fix it self... it was not correctly adjusted at first and then due to cable stretch or some other cable tension change, you rode it into adjustment... give it another few hundred miles and it will probably start skipping again.

Nope. The cable is somewhere around 8-10 months old with a few thousand miles gone by. And.. it never 'skipped' as you say. Like the OP's bike, it shifted fine; just dropped to the lower cog when cross chained and pedaling backwards (who cares).

*Nothing* changed. No adjustments made. That was my point.

BTW, cables don't stretch. They seat after a couple of hundred miles.

Do you even work on your own bike?