Chainwheel run out

[MALT]

Hi guys / girls.

Recently upgraded from a viceless mountain bike to a veteran road bike.

The road bike has a relatively new triple chainwheel fitted.

When I am in top gear, the chainwheel run out increases slightly with the load on the pedals, which means the chain rubs the chainwheel derailer for a quarter of the revolution of the crankset.

Any advice on how I can overcome this - adjusting the derailer stop screws has very little, if any, effect.

Also I don't seem to be able to select the shortest ratio chainwheel when I need it, so have to cope with hills in a higher gear than ideal.

MALT

 

[sight-pin]

Could be the cable needs adjusting? take up the slack either by loosening the cable clamp and pulling tight or by the adjuster at the gear lever end.

Edit, Also check for any play in the BB.

 

[KneesUp]

Has the FD got enough movement to cope with a triple?

 

[MALT]

Thanks for the replies.
I don't think it is a cable tension problem.
Not sure how the brake lever gear shift works though, is it possible to increase the total movement from them?
It is entirely possible that the triple requires too much movement of the derailer. If that is the case, will I need to replace the FD and the shift/brake lever?

 

[MALT]

No, there's no detectable play in the crank bearings when checking them static.

 

[Sharky]

Are the chain ring bolts all tight?

 

[Poacher]

Do you know if the relatively new triple replaced an older triple or a double? Difficulty engaging the smallest ring could be due to having a shorter BB axle than needed for a triple. There's also the possibility of incompatible tapers on the axle and chainset, e.g. Campag chainset on a Shimano BB; I run this combination on my Spa tourer and worry that it may be the cause of a slight occasional rubbing and various creaking noises under pressure, although this is more likely to be my knees protesting.
See this article by saint Sheldon.

 

[MALT]

Thanks for your reply Poacher. My rear tyre went flat on a run yesterday. This evening I changed the inner tube and when I went for a test ride afterwards I noticed that the left crank was creaking. On closer inspection I found that there was play in the crank taper on both sides. This play all went away when I tightened the screws in each side... and hey presto the run out has disappeared too!