Chainline on 10 speed

funkyjebus

Hi Folks,

Picked up my new cx bike yesterday but when I am on my large chainring and on my largest cassette sprocket the chainline seems far too severe, so much so that if I backpedal the smallest amount (eg, setting up pedals at traffic lights) the chain slips gears to the next sprocket (I know the chainline will never be perfect and is not an ideal ratio to be using, but I assume it shouldn't be slipping gears as a result). The problem goes away once I use lower gears and the chain line straightens.

Other than that the gears are as smooth as I silk.

Any ideas why this is happening, never happened on my road bike and I upgraded that myself.

DirkVoodoo

Eh, cross chaining?

This is a big no-no.

EDIT: The jumping could be caused by an improperly adjusted limit screw, but without diagnosing the problem with the bike present, this is just a guess.

funkyjebus

Oh I know it a no no, I was waiting for someone to chastise me:o. I actually only noticed it when I had the bike on the workstand last night. But still this bike is new and the slipping shouldn't happen. Given that its new, I think the the crossing is beside the point!

EDIT: Its not the front mech, there is no chain rub at all.

DirkVoodoo

funkyjebus wrote: »

Oh I know it a no no, I was waiting for someone to chastise me:o. I actually only noticed it when I had the bike on the workstand last night. But still this bike is new and the slipping shouldn't happen. Given that its new, I think the the crossing is beside the point!

EDIT: Its not the front mech, there is no chain rub at all.

Rear derailleur. Can you run your smallest gear without any issue (small front, large rear)?

funkyjebus

DirkVoodoo wrote: »

Rear derailleur. Can you run your smallest gear without any issue (small front, large rear)?

Yep, as I said this is the only issue I have with gear, other than that they are perfect.

As i look at the chain its really visable that its crossing (a lot more than my road bike), it looks like the cassette could use a spacer behind it or he chainset needs to be in further to the frame (but all looks installed correctly).

DirkVoodoo

Could you stick a photo up?

funkyjebus

Yeah, tried to take one at lunch but turned out crap. I'll get one up later today. Cheers Dirk.

cdaly_

funkyjebus wrote: »

Picked up my new cx bike yesterday but when I am on my large chainring and on my largest cassette sprocket the chainline seems far too severe, so much so that if I backpedal the smallest amount (eg, setting up pedals at traffic lights) the chain slips gears to the next sprocket

funkyjebus wrote: »

But still this bike is new and the slipping shouldn't happen. Given that its new, I think the the crossing is beside the point!

I'd say it's a combination of the crossing and the newness. Over time the chain will loosen up a bit and it's less likely to slip off. Because you're backpedalling, there's no derailleur to keep the chain on the largest sprocket and it tends towards the next one.

Quit cross-chaining and the problem will go away.

victorcarrera

DirkVoodoo wrote: »

Could you stick a photo up?

Definatey, crosschaining and generally back pedaling are 2 no nos on derailer gears but.
Can you show us the angle of the rear mech arm when the chain is in big front ring and big rear sprocket.
The chain may be too short.
Otherwise I would say it is because the chain is new and has no lateral play.
Next time you are stuck at the lights, apply the front brake, push the handlebars forwards until the rear wheel is off the ground, then rotate the pedals (forwards) to the required start position.