Gear set problem. Single Speed

StephenJ

Ive just converted my MB to singles speed to try and reduce maintenance, but I seem to have a peristant problem, one which I had when I had before I did the conversion.

Pedaling at low speeds everthings ok, but when I put a bit of power on, I get like a 'jolt' or jerk, like there is some 'give' in the system. The speed at which this happens makes it difficult to determin where this is coming from- the freehub, bottom bracket or the chain, im not sure.

Ive got a 44t chainwheel with 16t at the rear (all shimano deore). The Chain, an SRAM powerchain, appears to be OK (tension wise and its well lubricated), ive got a chain tensioner (powerplay chain tensioner) which seems to be working ok. Chain, gears and tensioner seem to be all aligned.
Everythings new except for the chainring,carnk and bottombracket

Thought that ratchet mechanism in the freehub body may be to blame so got replacement - Problem still there

Bottom bracket is fairly new and appears ok

Anyone got any ideas? could it be the chainwheel? Its fairly new

Thanks

Steve

nicklouse

sounds like some thing is not aligned and i guess you are using the original cogs that have the shifting ramps on them and the chain is being picked up on them.

rest the bike vertical against a wall and check the alignment.

StephenJ

Thanks for reply

Ive tried a number of cogs, at the moment ive got a cog very similar to the one in the DMR single speed conversion kits, with very basic teeth profile.

II'll have a closer check of the alignment again next chance I get. I do recall, when I turn the cranks, the chain did appear to run smoothly.

cheers

Steve

redvee

Alignment is my suggestion, though it could also be the sprocket. It made a hell of a difference when I changed from a cassette sprocket to a non-ramped etc sprocket. Now running a Surly sprocket.

StephenJ

Hi there,

Ive rechecked the alignment, this seems OK.
The chain is OK - tested all the links and its well lubricated.

Im beginning to think it could be either my chainring or bottom bracket.

Just to recap, the problem I have is that when im peddaling lightly everything is fine, its only during the moment that I put some effort into peddaling that I get a jolt (something gives).
It happens so quick that its not possible to see whats wrong, plus I can only replicate it when im on the bike pedalling hard.

The bottom bracket is fairly new and seems to work ok, but the moment when Im pedalling hard it could be a problem with the bearings giving away a little.

Does this seem likely / logical?

Thanks for your opinions

Steve

nicklouse

sorry bike shop time.

Drfabulous0

Had a similar problem with my wife's bike a while ago. In the end I had to put the bike in a turbo trainer and watch the drivetrain while someone put the power down. This revealed an alloy FSA chainring had worn out in around 3 months.

Anonymous

I had a similar problem on my (admitedly non-singlespeed) bike. It turned out to be a damaged tooth on my middle chainring.
Under load, the chain would be forced on to the top of the teeth on the chainring (not sitting in the gaps), for about half a revolution and then it would suddenly SNAP back into the proper place.
It was hard to spot what was going on, but I first noticed it was something to do with the chainring by looking down, and pedalling really hard (dangerous! make sure there's no trees/oncoming traffic!) uphill. It became quite apparent that something odd was going on.

saintadolf

you can pick up a ss conversion kit for a tenner (spacers and cog) so if u use that and your still having probablems then its aalmost definatly your bottom bracket

hoathy

This is going to sound stupid, and i'm sure you've already checked this, but it might be chain tension, when I first converted to SS i was using a tensioner and I reckoned I'd got it about right, it'd be fine in the work stand and when pedalling normally, but if i got up on the pedals or tried a bit harder genrally i could make it slip. I was so sure it coudln't be tension, but it was... can you remove anymore links from the chain?

caw35slr

I used an OnOne Doofer chain tensioner that allowed be to adjust the position of the tensioners jockey wheel so that it was on the chain line. I found this to be quite a sensitive adjustment - a little bit wrong and I'd get symptoms not unlike yours.

I also used an OnOne singlespeed convertion which is a straight swap for a 9-speed cassette. It came with two spacers of differing widths which gives you a change to make a fairly sweeping chainline adjustment. I used a Deore triple up front with two rings removed and achieved a decent, working singlespeed.

Persevere! :-)