Amount of chain play for IGH drivetrain

PersonalJesus

Hi folks,

After recently repairing a puncture on my commuter i my chain seems to have much more play than i would expect i.e ~ 1" in either direction from rest position. The chain seems to be slipping when under strain in the "neutral" 4th gear, and seems to taking more effort than before pedalling in normal conditions.

Bike is just over a month old, has a shimano nexus 8spd, no eccentric bottom bracket, tension seems to just be adjusted by position in the dropouts, and as far as i can tell ive taken up as much slack as possible i.e. the hub sits as far back in the dropout as possible.

Is this a case of shortening the chain and just adjusting the tension with the dropouts? Unfortunately the manufacturers (cube) manuals make no reference to this, nor does the shimano nexus manual. Im due a free service with CRC where i bought it from which is cool but would like to understand this myself in the meantime.

Thanks!

Doctor Bob

If the BB isn't eccentric, then I assume your dropouts are horizontal. (My Nexus 8-equipped bike has vertical dropouts, so needs an eccentric BB- consider yourself lucky you don't have one!) If so, and the rear axle is as far back as it goes, then I suspect Yes, the chain needs to be shortened. Having said that, it sounds like the chain has stretched quite a lot if the bike is only a month old. It really shouldn't stretch that much in such a short time. It's also worth bearing in mind that there should be some play in the chain when properly tensioned, but two inches is definitely a bit too much.

The problem with slippage in 4th may be a separate issue, though, and might require adjustment to the indexing of the hub- this is a pretty standard 'bedding in' issue. The Nexus 8 manual should give guidance on that (lining up the yellow lines on the two parallel parts, etc.). But really, if you're due a free service, I'd use it asap.

Holyboy

If your non turn washer tabs are facing to the rear of the dropouts you can take them off and flip them 180 degrees which will give you more room to pull the wheel back, I really don't think the chain should need shortening after a month!

Moving the wheel will have no affect on the shifting though as the cable is attached to the hub via the cassette joint unit so is the same no matter where the wheel is, but if the hub is slipping you should get it looked at as it will get damaged if you ride it out of adjustment.

PersonalJesus

Ah the washers would make sense, did think about their orientation other than left and right. The gear cable adjuster at the shifter doesnt appear to affect the yellow line alignment for me at all though?

Will be getting it into the shop at the weekend anyway and will have a word with their mechanics.

Cheers lads.

cdaly_

When you're in the shop, ask them to walk you through the gear adjustment...