trouble with triple chain set

[dav581005]

Hi all hope you can help I have just bought a road bike off eBay and after snapping the chain first time out on it I took it to my local LBS who replaced the chain and rear derailleur and sorted everything out but informed me that the front derailleur wasn't working properly and was caused by the previous owner changing the chainset from a double to a triple without changing a bottom something can't remember what it was he said now does anybody know what this is and is it difficult and/or expensive to change thanks

 

[cyberknight]

Triple chainsets have a longer bottom bracket axle to accommodate the triple crankset , also triple front derailliers generally have a wider cage and finally the shifter has 3 clicks rather than 2 .
IMHO if the bike was advertised as a working triple i would put a resolution into ebay for a refund .

 

[dav581005]

To be honest I would do but the bike only cost me £100 and the guy in LBS said even if I spent another hundred it would be well worth it. as it is now I am just running on the small and middle chain ring and it is fine but would obviously want it running right really. shifter is a three speed shifter. guy at LBS said all it needs is a bottom bracket that is correct for the chainset but didn't put a price on it.

 

[accountantpete]

A new BB with the longer axle will only be £15 plus small fittings costs. I'd get the LBS to do that as you need special removal tools and the old BB can get a bit hard to take off.

 

[ColinJ]

If the small and middle rings are working ok, why would a longer BB axle be needed i.e why push the rings further out with a longer axle when they are not currently causing problems on the frame or derailleur?

 

[boydj]

If the small and middle rings are working ok, why would a longer BB axle be needed i.e why push the rings further out with a longer axle when they are not currently causing problems on the frame or derailleur?

Agreed. Sounds like moving the outer limit screw is all that is required, or maybe a cable change. Both screws would have to be moved if a longer axle is fitted. Presumably the front mech worked properly at some stage with the current bb.

 

[Ian H]

Sounds suspiciously like the BB is too long. If there's a large gap between inner ring and chainstay then that's probably it. You don't need more than approx 5mm. Bottom brackets do not need to be expensive.