thespaceman

Hi all,

I've just received my daughters new bike but there appears to be a problem with the crank and the chain. The crank rotates ok but is quite stiff so I guess the bearings are too tight?

The other problem is that when in gear 1 (largest rear cog) and pedaling backwards the chain slips off first gear and lands on second. The problem doesn't happen on gears 2-6. There is only 1 fron cog.

Is this something to do with the chain line or could it be a bent front cog spindle or something else?

Any advice welcome!

2manybikes

Your bike is not designed to pedal fast backwards. There is no guide to guide the chain on the cog and the tensioner on the derailleur will not work correctly in reverse. Don't pedal the thing backwards fast. Don't worry about what it does in reverse, only forward. There is no indication that anything is wrong with the chain except you are pedaling it backwards too fast.

It does sound like the bearings are too tight. Is it stiff in both directions?

JiveTurkey

It's also possible the Low limit screw on the rear derailleur is set too tight.

AndrewP

Limit screw setting wont make any difference when pedaling backwards.

erader

why are you pedalling backward....you are supposed to be pedalling forward !

ed rader

Air

Are you already in a gear before it jumps off? Make sure you give it a few good cranks forward before trying to pedal backwards - I can pedal any of my bikes backwards without an issue. When there is it's usually that the chain isn't greased and the rear deraileur hangs up and makes it jump.

mcoomer

As the others have said, pedal forwards. As long as there is no problem when riding normally I wouldn't worry about it.

I suspect that the Low adjust may be a bit off a slight bit causing the chain to ride just to the outside of the large cog instead of being centered on the cog. It may not be off enough to cause trouble but if your daughter notices her chain jumping off the large cog to the second cog you may need to adjust it or if the bike is new take it back to the shop and have them do it.

Mike

thespaceman

Thanks for the responses guys. Ok I know she shouldn't pedal backwards but it even happens when she is trying to bring the pedal up when starting off.

Anyway I took it to a local bike shop and the guy slackened off the bottom crank off a bit so it now turns fine.

What he did say though that the bottom bracket is too long and as this is making the chain wander outwards. He said that there wasn't much that could be done as the outside of the front cog is nearly touching the frame and the longer bracket was fitted to provide clearance.

I might get away with a shorter bracket so will see how she gets on and consider fitting one later. I wonder if other Raleigh Sunbeam owners have the same problem?

Cheers.

DannoXYZ 

You could get a smaller large-chainring and that'll let you use a shorter BB-spindle. Most bikes are geared for 45mph+ top-speed of pros, most people end up hardly ever using their big-chainring as a result.

Also, the chain coming down when spinning backwards is due to the angle of the chain. It's aimed over towards the outside at the top after it comes off the big bog. It's like there's an invisible derailleur on top pushing the chain sideways. Just be sure to be in the small-chainring when you're using the three biggest cogs in the back and it'll reduce this amount of sideways chain-flex. Less-friction, the chain will last longer and you'll go faster as well.

Portis

I use my big chainring 75% of the time, and my cadence is around 85-90. It also helps that is is mainly flat, but it is a fact that a LOT of people use their big ring.

AndrewP

Note in the original post - there is only a single chainring. Your duaughter will only need to use the biggest cog at the back when pulling up steep hills. When starting off on the flat she should be in one of the middle gears at the back.

1901

Had same problem. It was the chain; it was made of a very weak metal and was too flexible sideways.
Was able to pedal forward. The derailleurs were keeping the chain in place, but when tried to pedal backward the chain slipped from both chain-ring and freewheel. It didn't happen on all speeds. Just for the sprockets that were not aligned with the chain-ring. Out of 7 speeds/sprockets, I was able to pedal backwards on only 3 of them (on speeds 3-4-5).
Tried to get used to it and use the bike as is, but the chain broke in about 100m; at the first stop (I suppose the chain is most stressed when you stop) Changed with another identical chain and it also broke in 100m. Those bad chains costed me less than 1€ each. Changed with a better chain made of strong steel and less flexible sideways that costed 3€ and I no longer have any problem pedaling backward.

fietsbob

What Big headlines you have, there.. 1901..

BCRider

A couple of hints about forum posting etiquette.

It's not really sporty to bring back threads that are more than about a year old unless there's a good reason. Such as you're the original poster coming back with a followup. Or unless you had the same problem. And even when you have the same issue as the previous poster it's more suitable to start a new thread than to bring a 5 year old one back from the grave.

Also it's not nice when you Yell in big letters or TYPE IN ALL CAPS. Both are seen as the internet version of screaming.

JiveTurkey

It's always a shock to start reading through a thread, not paying attention to the dates, and scroll down and see an ancient post of my own.

Old Hammer Boy

Had a similar problem on our tandem. Turned out the "b" adjustment needed tightening up, which removed excess slack from the chain and kept it on track.