Sram x7 issues

paul_stelling

Please can anyone help . I have a rock hopper pro evo 29er with Sram x7 rear derailleur. I seem to keep having the same problem when the chain has been slapping up and down on the trails the derailleur seems to lock leading the chain very slack which then leads to it doubling up and crunching into chain rings. The option is to get off bike and grab the thing and give it a yank to spring back. This is very annoying as it's ruining my gloves and also tacking the enjoyment out of my riding as I keep getting left behind. Is there anything I can to to prevent this happening ie gear changes or adjustments that could be made . Many thanks.

FishFish

Had a similar problem with Shimano Saint. Although maybe not the same issue or solution for you I worked out that the cause was the bolt holding the derailleur to the hanger had loosened and this caused the mech to rotate forward and leave the chain loose.

Therefore pulling it back and tightening the bolt solved the problem for me. Not Nobel prize winning engineering but a strangely satisfying fix.

Happy New Year!

The Rookie

When you say the chain is doubling up into the chainrings, it sounds like you are describing chainsuck, that's not a rear mech issue.

paul_stelling

Thanks for the reply s . What is chain suck caused by ?

The Rookie

Worn chainring or poor lubrication/muck, basically the chain stays 'sucked' onto the chainring and gets pulled up into the frame.

paul_stelling

Thanks I. Will check out.

paul_stelling

On further investigation I have found that the front chain rings especially the small one is worn out thus causing chain to stay sucked to it and continuing round and jamming. The cost of replacing both rings and the fact that the rear x7 mech seems to have lost its tension in the spring I have decided to ditch the sram and go for shimano xt and make it single chain ring conversion. Can anyone recommend a sensible single speed crankset that won't break the bank that will suit 29er. Many thanks.

JGTR

Just use your existing crank with a narrow wide chain ring.

paul_stelling

Thanks will the chain line be OK. The lbs said had to change the crankset to get it right.

The Rookie

depends on what chainset you have now, if it's a triple or a double and bash then the middle/outer location is fine, if you have a double only then while neither location is ideal, either will work.

paul_stelling

Thanks rookie I have a samox 2 pc 2×10 crankset with bash guard. The current chainring s are 36/ 22 . Do I use the outer position then ? Also bearing in mind that it's a29er and I only use on trails what would be the best size chain ring to go for. I currently never use smallest 2 cogs while on large chainring . To give you some idea of the sort of riding I do . My current cassette is a 10 sp 11 - 36 . Will the cassette be OK or should I change that too. Many thanks.

The Rookie

To start with I'd just change the chainring and keep the cassette you have, a 32T or 34T would suite by the sounds of it.

I wouldn't initially shorten the chain so that if you decide to opt for a wide range cassette you could hopefully keep using the one you have on now.

paul_stelling

The Rookie wrote:

To start with I'd just change the chainring and keep the cassette you have, a 32T or 34T would suite by the sounds of it.

I wouldn't initially shorten the chain so that if you decide to opt for a wide range cassette you could hopefully keep using the one you have on now.

Thanks for all the advice it has been very helpful. I have now found out what the issues are so thought I would share incase anyone has similar problems. Basically there were a number of things going on that caused the chain to jam up or suck in. The BB had play as did the rear hub. Also front chain rings were badly worn too. So a combination of faults leading to the jamming up. So not really a rear mech fault at all although the hanger was a little bent but this could have been caused by me trying to free chain off when all jammed up.