Q: from 7 to 8 speed indexing with downtube RX100 changers?

pondweed

Old School Hero
I've got RX100 downtube levers which are connected to 7 speed block. There is presently a STX 8-SIS r.derailleur (presumably adjusted down on the stops) and on the strength of that I've bought an 8 speed block in the sales...

And now realised that the lever will be only 7 speed.

Is there an easy way of getting it all to work without abandoning the indexing. Or do I need new levers?
 
Hopefully you have 8spd wheels?

If so, adjust the mech so it moves the chain across the block. Connect cable to shifter as if you were connecting 7spd bits...

...then shift as normal and watch as the '7spd' Shimano lever magically shifts across the whole 8spd cassette!

I use 7spd levers for 8spd without too much issue - theres travel after the last 'click'allowing for that extra 8th cog
 
Re:

As the man says.I have three bikes running eight speed on seven speed suntour command shifters.Use the overrun on the shifter and use the mech stop screw as the last index point. So its seven clicks and a shove and you are in.
 
Re:

YAY! Thanks all...

I actually have a new-to-me rear RM30 Shimano hub, which looks like it has a spacer on it.

(But I was also thinking that if it is 7 specific, I could always buy a new wheelset rather than a new front to match the rear... not much difference in price and the R501s looking mighty tempting)
 
8 speed is 4.8mm per cog, 7 speed is 5.0mm. Usually you can get away with it (as said) due to the floating top jockey. If indexing is a bit rough, try setting the adjuster to get the rear mech dead central on the pulley to the cog for 4th or 5th.
 
got all this sorted fine.

But I wonder whether there is option to just get rid of indexing entirely on the rear RX100 shifter? As the front cog is by feel, I'd quite like the other to be so.... is it possible?
 
Re:

Believe it or not, my Gitane which is otherwise all Mavic, runs perfectly with RX100 shifters and an 8speed freehub. Mavic 840 ( I think ) mech that is.
The bike is not to hand right now, but there should be the option of friction or indexed, IIRC

Mike
 
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