Chain slip.

shauncwz

Likes Bikes
Hi guys, any advice would be appreciated.

I recently installed a Sunrace 10spd wide range cassette (11-40t) on my bike. And along with it a brand new KMC chain. Since then I have been experiencing chain slip while on the largest sprocket (10th), but only while putting loads of power down, like when climbing steep hills. The chain doesn't jump to the next sprocket, it just slips on the that same sprocket until it catches again. On the road/flats it doesn't slip, but I suspect that's because I am not able to put down enough power for it to slip. Does not slip on the second largest sprocket (9th) even if I stand and pedal up the same hills.

I run a 1x10 setup with a 32t NW chain ring up front. XT Shadow+ derailleur (long cage) out back. Hanger seems straight and I have properly setup up my derailleur (upper limit, lower limit and b-screw).

What do you guys think could be the problem? Would pedal bob due to the long travel of the bike cause a change in the chain line or chain tension and cause it slip? I have tried letting all the air out the shock and compressing it to see if the RD still has room to extend and it does have room left.

Left annoyed not being able to use the wide range to conquer them climbs!!
 

moorey

call me Mia
Pic of setup? B screw wound in so far not enough chain/cog contact?

edit....largest sprocket you say? Are you sure it's properly tuned? High and low screws set correctly?
 

shauncwz

Likes Bikes
Pic of setup? B screw wound in so far not enough chain/cog contact?

edit....largest sprocket you say? Are you sure it's properly tuned? High and low screws set correctly?
Yeah only slips on the largest sprocket. I'm pretty sure its properly tuned. I've tuned all my previous bikes and have got it right so far. Indexing of the gears are pretty spot on too.

I will take a picture tomorrow when its brighter. The b-screw is wound out as far as it will go before the jockey wheel starts grinding on the cassette.

Looking from the top, the big jockey wheel lines up perfectly with the largest sprocket, but the derailleur cage is sort of crooked. ie: small jockey wheel doesn't align with the cassette. Not sure if thats normal as I have never took notice of it before until today.
 

ChrisJC

Likes Bikes and Dirt
There's probably a contributor..... Designed maximum sprocket size is 36T, regardless of cage length.
yeah, that's what I was thinking! I've converted 3 bikes to 1x10 in the past few months, all with sunrace cassettes 11-42 and 11-40 with kmc chains. None of them have missed a beat; however I've used xt m8000 medium cage derailleurs to replace the existing m786 long cage derailleurs.
 

shauncwz

Likes Bikes
yeah, that's what I was thinking! I've converted 3 bikes to 1x10 in the past few months, all with sunrace cassettes 11-42 and 11-40 with kmc chains. None of them have missed a beat; however I've used xt m8000 medium cage derailleurs to replace the existing m786 long cage derailleurs.
=( So you've never used your m786 on your setup? Immediately went to the new m8000?

Reckon one of those RAD cages would solve the issue? What does the RAD cage do different anyways?
 

ChrisJC

Likes Bikes and Dirt
=( So you've never used your m786 on your setup? Immediately went to the new m8000?

Reckon one of those RAD cages would solve the issue? What does the RAD cage do different anyways?
Not really sure - I never looked into it much. I think you need a medium derailleur to use the RAD cage (I had a long cage) and it worked out to be more than a M8000 which only cost me $73
 

cvbass

Likes Dirt
Not really sure - I never looked into it much. I think you need a medium derailleur to use the RAD cage (I had a long cage) and it worked out to be more than a M8000 which only cost me $73
RAD cage only suit Medium cage but the newer RADr cage suits any. It moves the upper jockey wheel back out of the way as far as I know
 

shauncwz

Likes Bikes
Retuned my derailleur and shifter over the weekend. Made the higher limit closer towards the hub. I think that sorta made a difference.

Biggest surprise was when i stiffened my rear shock when climbing. No more slippage! Now wondering if pedal bob was the contributor to the whole slippage thing happening?
 

moorey

call me Mia
Retuned my derailleur and shifter over the weekend. Made the higher limit closer towards the hub. I think that sorta made a difference.

Biggest surprise was when i stiffened my rear shock when climbing. No more slippage! Now wondering if pedal bob was the contributor to the whole slippage thing happening?
If you have chain growth, it will stretch out the derailleur as shock compresses, and potentially reduce contact between chain and the cassette.....in the same way winding in the B screw will...as my mind sees it.
 
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