ricksavery
Über Member
- Location
- Poole, Dorset
I have a Shimano 11-34 rear 9-speed cassette, a 48-38-28 chainset from Spa Cycles, and Shimano LX front and rear derailleurs.
The rear setup works fine, and I can shift to all gears.
I have made an error on the front. Did not realise that there must be a 12T difference between middle and large chainrings.
Front derailleur hits middle chainring when shifting to large chainring.
So, I mounted derailleur higher up tube. No rubbing on any gears whilst in middle chainring, but on smaller chainring, there is rubbing in the low gears, making it all a bit pointless.
At first, I wasn't sure why Spa would sell a chainset with a 10T difference if this was an issue, but then reasoned that it must be OK in a 7-speed setup where the range of chain angles is not so great - and a company like Spa and loads of cyclists wouldn't sell/use it if it didn't work.
My stupid fault then for not having read the label on the tin!
As a temporary fix, I was thinking of lowering the front mech so the rubbing would stop, and not use the larger chainring (which i don't really anyway)
long-term options seem to be
1 Change the front mech to one which will work with chainset (don't seem to be many if at all)
2 Replace entire chainset
3 Replace middle (and smaller ?) chainring to give a 12T middle to large difference - was thinking of this to get a better lower range anyway
If I do replace the chainrings, would 48-36-24 work (ie a 24T overall difference) with the LX mech or would I have to be content with 48-36-26 ?
Would appreciate all advice on these options - and any others - are they stupid choices ?
Thanks for staying with the (long) question !
The rear setup works fine, and I can shift to all gears.
I have made an error on the front. Did not realise that there must be a 12T difference between middle and large chainrings.
Front derailleur hits middle chainring when shifting to large chainring.
So, I mounted derailleur higher up tube. No rubbing on any gears whilst in middle chainring, but on smaller chainring, there is rubbing in the low gears, making it all a bit pointless.
At first, I wasn't sure why Spa would sell a chainset with a 10T difference if this was an issue, but then reasoned that it must be OK in a 7-speed setup where the range of chain angles is not so great - and a company like Spa and loads of cyclists wouldn't sell/use it if it didn't work.
My stupid fault then for not having read the label on the tin!
As a temporary fix, I was thinking of lowering the front mech so the rubbing would stop, and not use the larger chainring (which i don't really anyway)
long-term options seem to be
1 Change the front mech to one which will work with chainset (don't seem to be many if at all)
2 Replace entire chainset
3 Replace middle (and smaller ?) chainring to give a 12T middle to large difference - was thinking of this to get a better lower range anyway
If I do replace the chainrings, would 48-36-24 work (ie a 24T overall difference) with the LX mech or would I have to be content with 48-36-26 ?
Would appreciate all advice on these options - and any others - are they stupid choices ?
Thanks for staying with the (long) question !