Chain Crossover

[Graham O]

All,

Well...I have now built up my commuter / winter bike and need a little advice.

Its all OK, but when the chain is on the bottom two sprockets of the cassette whilst on the lower chainset ring, the chain rubs against the upper chain ring. I have never seen this on any of my bikes and suspect that something is wrong.

Anyhow, I am contemplating a solution. Thought of the following;

1) Try to transfer a washer from the non drive to the drive side of the rear hub.
2) Buy a 42 tooth inner chainset ring.
3) Work around the problem (i.e. don't use the gears)

Any other ideas...

[sid_day]

Graham my first thought is that the BB axle might need to be longer.
Bottom brackets come in different shell widths and axle lengths.

Assuming you have built up with old bits a new BB shouldn't cost you the earth.

[Graham O]

Thanks Sid.....That seems to be the answer. If I muck about with the rear hub, it will probably go horribly wrong...

[sid_day]

Shimano Chainsets used to come with a little leaflet which told you what BB the chainset would work with.

Some of these leaflets are available on the european shimano web site here:
http://techdocs.shimano.com/techdocs/index.jsp

Example:
[url]http://techdocs.shimano.com/media/techdocs/content/cycle/SI/TIAGRA/FrontChainwheel/4400_4403/SI-1DM0A-En_v1_m56577569830612377.pdf[/url]
No use to you if you run campag obviously

[John the old'un]

[quote="Graham O"]All,

need a little advice.

Its all OK, but when the chain is on the [color=red]bottom two sprockets[/color] of the cassette whilst on the lower chainset ring, the chain rubs against the upper chain ring.
Any other ideas...

[Graham O]

Its all a bit confusing really - When I say bottom I mean 12 and 13 sprockets !!

[John the old'un]

[quote="Graham O"]Its all a bit confusing really - When I say bottom I mean 12 and 13 sprockets !!

[Graham O]

Is that top gear on the front top chainring or top gear in the Rapha Catalogue....

Only messing....Use of Top and Bottom noted, until next time that is.

[John the old'un]

[quote]

Slow day in the office? Same here mate