Kathmandu front sprocket

[John Frum]

I have a Cube Kathmandu with a 10 speed Shimano cassette. When I replaced the slightly worn chain recently I started experiencing "chain suck". The new chain is a correct Shimano unit with identical number of links to the outgoing and I cleaned the entire gear train first. The cassette is in good shape. Replacing the original chain eliminates the problem. It's hard to believe that the tiny difference in chain pitch caused by minimal stretching would account for the difference.
One problem I have is that it's almost impossible to check the front sprocket thoroughly as the chain guard cannot be removed without (I think) dismantling the crank (etc?) Several questions arise:
1) Any suggestions as to the fault?
2) What tools are required to remove the chain guard and drive sprocket?
3) What is the spec for the replacement sprocket? I assume it's a standard Shimano unit rather than Cube-specific.

My experience of Cube is that asking for answers to anything at all is completely futile so I'd appreciate any help forum participants could offer.
Many thanks
Johnno

 

[stevenatleven]

My wife has a Hybrid one with the same chain guard, it is difficult to see how to remove it. I will turn it over tomorrow and see if I can figure it out, failing that I'm going to the Cube dealers next Wed so will ask the mechanic there. Hope you find out before that.

 

[stevenatleven]

My wife's bike a Cube Touring Hybrid One has two 3mm Allen bolts between the crank spider to remove chain guard, plus the one at the rear. Doesn't look like the brackets go round the bb so should be ok to remove.

 

[Phil Dryden]

My wife has a Hybrid one with the same chain guard, it is difficult to see how to remove it. I will turn it over tomorrow and see if I can figure it out, failing that I'm going to the Cube dealers next Wed so will ask the mechanic there. Hope you find out before that.

I had a Kathmandu until recently, and from what I remember, there is a small screw to remove at the rear of the plastic guard, and thereafter it is held in place by one or two plastic clips moulded onto the back of the guard which press into plastic mounts on the motor housing. It requires a little courage to prise them out as they are held firmly in place and it is a bit of a heart stopping moment in case anything cracks or breaks! I made sure they were heavily greased before replacing the guard. In actual fact I eventually upgraded the front 15T sprocket with an 18T one to raise the gearing, and found that I had to hacksaw one of the plastic mounts off as it fouled the new run of the chain, so the guard became redundant!