Stripped threads on pedal/crank.

[Brandane]

Not all crank sets take the same spindle length. It could be that the new crank set requires a shorter bottom bracket spindle, for instance, 118mm instead of 122mm.

In general, for a double, the crank set should end in a position so that there's minimal chain deflection when the chain is in the middle sprocket at the back. If not, chainline is wrong, and chain wear will be quicker.

Thanks, this could well be the issue. The new chainset, on further investigation, should be using a 107mm spindle, rather than the one fitted to the bike which IIRC is 116mm.. Time for another visit to the ChainReaction website!

 

[midlife]

If you are thinking about something like a shimano un55 it pays to shop around as they are on special offer somewhere most of the time

 

[Blue Hills]

that could be it.

Have had dramatic results shifting from a 110 to 113 spindle BB.

Check out Rose of germany if ordering such things - other items can justify the postage/courier costs.

 

[C R]

Thanks, this could well be the issue. The new chainset, on further investigation, should be using a 107mm spindle, rather than the one fitted to the bike which IIRC is 116mm.. Time for another visit to the ChainReaction website!

That's a very big difference, shifting and chainline to the larger sprockets will probably be awkward.

 

[winjim]

I don't know the value of your chainset but as it's brand new, fitting a helicoil may be worthwhile. Something like this - https://www.ebay.co.uk/itm/PEDAL-TH...hash=item1c9a5c3220:m:mp31IFcbz6YptYB9dar0Msw

A proper garage, LBS or engineering shop should be able to fit it for you if you don't feel confident.

Takes about ten minutes, a bit longer if you want to let the threadlock set, and slightly longer still if you want them to file down the bit that protrudes on the inside of the crank (I didn't, I was in a rush) but it's an essentially invisible repair (it's hidden by the pedal) and of course actually strengthens that part of the crank as the insert is steel rather than aluminium.