chain problems on single speed cruiser

in message <[email hidden]>,

(' ') said:

I am having intermittent drive train problems on a Schwinn SSX Single
Speed cruiser that I recently bought new. I ride the bike about 3
miles to the station and along the way the chain is prone to jumping
especially under load or when going along a bumpy road. The chain
often drops off the cogs completely once or twice along the way. It
also tends to jam the pedals from moving forward and if I pedal
backwards very slightly and forwards again it seems to avert the chain
from falling off.

The bike shop said it might be a chain tension issue and they
installed a new chain and apparently set the tension.

This really should not happen.

On a single speed it's pretty important that the chainline is straight - in
other words that the sprocket on the rear hub is in the same plane as the
chainwheel. You can check this by sighting along the chain - does it look
straight? If it isn't, take it back to the shop where you bought it and
tell them to fix it.

Next, the chain should not be bar taut, but you should not be able to lift
the chain in the middle of its run by more than about half an inch. If you
can then it is not tight enough.

At the end of the rear forks there should be a slot on each side which is
more or less horizontal (or else there should be an eccentric bottom
bracket, but this is more unusual and usually only on expensive bikes).
The ends of the axle sit in this slot, and are (on single speeds) held in
place by two large nuts. To adjust the chain tension, slacken the nuts and
move the axle back until the chain is taut enough (test as stated above),
then tighten the nuts firmly. What I suspect is happening is either that
the bike shop didn't tighten the nuts enough, or else they aren't gripping
well enough; in either case the axle is slipping forward under load.

If this continues to happen after you have adjusted the chain and tightened
the nuts firmly, you could fit 'chain tugs', which prevent the axle being
pulled forward.

http://www.wiggle.co.uk/ProductDetail.aspx?ProdID=5300005220

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; may contain traces of nuts, bolts or washers.

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Hi

I am having intermittent drive train problems on a Schwinn SSX Single
Speed cruiser that I recently bought new. I ride the bike about 3
miles to the station and along the way the chain is prone to jumping
especially under load or when going along a bumpy road. The chain
often drops off the cogs completely once or twice along the way. It
also tends to jam the pedals from moving forward and if I pedal
backwards very slightly and forwards again it seems to avert the chain
from falling off.

The bike shop said it might be a chain tension issue and they
installed a new chain and apparently set the tension.

They've probably fixed it - it's possible they know there's an issue
with poor quality chains on these bikes[1] and they routinely replace
them with better ones if they cause a problem.

Quoted message said:

Any ideas as this has lost my confidence in the reliability of the
bike. I am wondering if it is more of an alignment problem but all
looks ok to me....

It could be a number of things. Here's how to check for some of them:
Take the chainguard and chain off and turn the cranks while looking
closely at the teeth on the chainring from above - if a tooth is bent or
if the chainring is warped it should be fairly obvious.
Repeat with the rear sprocket, although excessive float and bent teeth
are pretty unlikely there.
From the front, sight along the inside of the chainring to the inside of
the rear sprocket - they should appear pretty much in line.
Refit the chain, make sure the rear wheel is centred in the frame and
pulled back as far as it will go to tension the chain.
Turn the cranks backwards - there shouldn't be any tight spots in chain
tension. If there is a tight spot reset the chain tension at that point
and check again. Check for loose spots - finger pressure on the middle
of the chain run shouldn't move the chain vertically by more than half
an inch or so. If you can't eliminate tight spots without creating
excessively loose spots the chainring might be off-centre and need
replacement.
Turning the crank backwards, watch the chain as it comes off the bottom
of the rear sprocket - any stiff links should be fairly obvious, you
might be able to free them off by hand by bending the chain from side to
side a few times, otherwise you'll need a chain rivet tool.

[1] I'm only guessing, but I've seen this sort of thing before.

Rob Morley said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Hi

Quoted message said:

I am having intermittent drive train problems on a Schwinn SSX Single
Speed cruiser that I recently bought new. I ride the bike about 3
miles to the station and along the way the chain is prone to jumping
especially under load or when going along a bumpy road. The chain
often drops off the cogs completely once or twice along the way. It
also tends to jam the pedals from moving forward and if I pedal
backwards very slightly and forwards again it seems to avert the chain
from falling off.

Quoted message said:

The bike shop said it might be a chain tension issue and they
installed a new chain and apparently set the tension.

They've probably fixed it - it's possible they know there's an issue
with poor quality chains on these bikes[1] and they routinely replace
them with better ones if they cause a problem.

Quoted message said:

Any ideas as this has lost my confidence in the reliability of the
bike. I am wondering if it is more of an alignment problem but all
looks ok to me....

It could be a number of things. Here's how to check for some of them:
Take the chainguard and chain off and turn the cranks while looking
closely at the teeth on the chainring from above - if a tooth is bent or
if the chainring is warped it should be fairly obvious.
Repeat with the rear sprocket, although excessive float and bent teeth
are pretty unlikely there.
From the front, sight along the inside of the chainring to the inside of
the rear sprocket - they should appear pretty much in line.
Refit the chain, make sure the rear wheel is centred in the frame and
pulled back as far as it will go to tension the chain.
Turn the cranks backwards - there shouldn't be any tight spots in chain
tension. If there is a tight spot reset the chain tension at that point
and check again. Check for loose spots - finger pressure on the middle
of the chain run shouldn't move the chain vertically by more than half
an inch or so. If you can't eliminate tight spots without creating
excessively loose spots the chainring might be off-centre and need
replacement.
Turning the crank backwards, watch the chain as it comes off the bottom
of the rear sprocket - any stiff links should be fairly obvious, you
might be able to free them off by hand by bending the chain from side to
side a few times, otherwise you'll need a chain rivet tool.

[1] I'm only guessing, but I've seen this sort of thing before.

Thanks for the great advice, will do some more investigation! - Steve

Quoted message said:

Rob Morley said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

Quoted message said:

Hi

Quoted message said:

Quoted message said:

I am having intermittent drive train problems on aSchwinnSSXSingle
Speed cruiser that I recently bought new. I ride the bike about 3
miles to the station and along the way the chain is prone to jumping
especially under load or when going along a bumpy road. The chain
often drops off the cogs completely once or twice along the way. It
also tends to jam the pedals from moving forward and if I pedal
backwards very slightly and forwards again it seems to avert the chain
from falling off.

Quoted message said:

Quoted message said:

The bike shop said it might be a chain tension issue and they
installed a new chain and apparently set the tension.

Quoted message said:

They've probably fixed it - it's possible they know there's an issue
with poor quality chains on these bikes[1] and they routinely replace
them with better ones if they cause a problem.

Quoted message said:

Quoted message said:

Any ideas as this has lost my confidence in the reliability of the
bike. I am wondering if it is more of an alignment problem but all
looks ok to me....

Quoted message said:

It could be a number of things. Here's how to check for some of them:
Take the chainguard and chain off and turn the cranks while looking
closely at the teeth on the chainring from above - if a tooth is bent or
if the chainring is warped it should be fairly obvious.
Repeat with the rear sprocket, although excessive float and bent teeth
are pretty unlikely there.
From the front, sight along the inside of the chainring to the inside of
the rear sprocket - they should appear pretty much in line.
Refit the chain, make sure the rear wheel is centred in the frame and
pulled back as far as it will go to tension the chain.
Turn the cranks backwards - there shouldn't be any tight spots in chain
tension. If there is a tight spot reset the chain tension at that point
and check again. Check for loose spots - finger pressure on the middle
of the chain run shouldn't move the chain vertically by more than half
an inch or so. If you can't eliminate tight spots without creating
excessively loose spots the chainring might be off-centre and need
replacement.
Turning the crank backwards, watch the chain as it comes off the bottom
of the rear sprocket - any stiff links should be fairly obvious, you
might be able to free them off by hand by bending the chain from side to
side a few times, otherwise you'll need a chain rivet tool.

Quoted message said:

[1] I'm only guessing, but I've seen this sort of thing before.

Thanks for the great advice, will do some more investigation! - Steve- Hide quoted text -

- Show quoted text -

FYI - Took my bike back to the bike shop and this time they noticed
two things:

- The front chain ring was slightly bent if the rotation is viewed
from above. This could have caused the back wheel to be slowly forced
out of alignment and eventually lead to the problems I am seeing...

- Also, while chain tension throughout one revolution of the chain
ring can be slightly different my chain ring when rotated display
large differences in chain tension. Making it difficult to maintain
proper tension throughout the revolution.

All in all I will probably replace the chain ring and all should be
OK.

Thanks
S

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

FYI - Took my bike back to the bike shop and this time they noticed
two things:

- The front chain ring was slightly bent if the rotation is viewed
from above. This could have caused the back wheel to be slowly forced
out of alignment and eventually lead to the problems I am seeing...

If that's what they said then I reckon they're either clueless or trying
to baffle you with [censored].

Quoted message said:

- Also, while chain tension throughout one revolution of the chain
ring can be slightly different my chain ring when rotated display
large differences in chain tension. Making it difficult to maintain
proper tension throughout the revolution.

They should have spotted that when they fitted the new chain.

Quoted message said:

All in all I will probably replace the chain ring and all should be
OK.

I wonder if maybe you should find a bike shop where the staff don't wear
Stetsons. Was this the same shop that sold you the bike?