lower ratios

[bygone era]

I have a tourer 2nd hand dave marsh 531 bike it came with campag 8 speed groupset the front is 30 40 50 with triple mech 8 speed exa drive shifters and a med cage mirage rear mech and 13 to 26 rear I would like to go lower for touring but does that mean replacing with shimano to get a low of around 25 inches I have a long cage acera rm which goes upto 34 but would need a wheel that accepts a shimano cassette and would the velocetriple be able to handle a low 24/6 on front?

 

[DCLane]

You could use a Miche Primato cassette. This one goes up to 28 teeth: https://www.ebay.co.uk/itm/Miche-Primato-M-Cassette-8-speed-Miche-Campagnolo-compatible/202380877820

Otherwise a Shimano compatible wheel with larger cassette is worth a try. The medium cage might work as 8 speed is interchangeable.

 

[MichaelW2]

8 speed Campagnolo has different cog spacing to Shimano 8. CTC has an article on cross compatibility of that era. I just switched everything to Shimano 9 which was a shame because the front micro-indexing shifter can work with any front ring/ mech combo

 

[bygone era]

8 speed Campagnolo has different cog spacing to Shimano 8. CTC has an article on cross compatibility of that era. I just switched everything to Shimano 9 which was a shame because the front micro-indexing shifter can work with any front ring/ mech combo

what does the rear spacing need to be for a 9 speed ie 130 please

 

[MichaelW2]

I have 9 speed in 135 OLD.
I was referring to the inter-cog spacing which must be compatible with the cable pull per index and the rear mech movement per cable pull (shift ratio).

CTC information here.

 

[Ajax Bay]

what does the rear spacing need to be for a 9 speed ie 130 please

What dimension are you asking about?
The hub OLN will be 130mm (road bike, Campagnolo or Shimano freehub) but your Dave Marsh frame drop outs may be at 126mm.
If you're asking about spacing between sprockets on a 9 speed cassette, look at Sheldon's cribsheets.