compatibility 7 spd downtube shifter '87 with 8spd cassette?

[pondweed]

I've been finding that the extra indexing stop works quite well with an extra cog added on the cassette, (bike was 3 x7 and I'm now running 3 x but now I'm starting to road test I've realised that the indexing distances may well not be right... I am getting chatter on the upper/larger rear rings.

Can someone confirm that either my 1987ish 7 spd RX100 shifters will technically work (and thus may need clean or overhaul) over the 8 speed range, OR will NOT!

I'm wondering about the DT Sunrace 8 spd braze on if I do need something else. Any thoughts on those? Or am I better spending another 25 quid and getting Ultegra bar-ends kit..

Thanks...

 

[hamster]

The spacing of 7 and 8 speed is not the same, despite what internet experts say: 7 is 5.0mm, 8 is 4.8.
Usually it works OK, provided cables are clean and a bit of fiddling is done. Add dirt and wear and it goes downhill. It is always better to run with the right stuff - and 8 speed levers are still available new from people like Ribble.

 

[rogerzilla]

Re:

...which is why my MTB with XT thumbshifters will be a 7 speed and won't use the extra ghost click. I'd rather have precise, reliable shifting than the extra gear. How many sprockets do you really need with a triple up front, anyway?