Shimergo 8 -> Campag 10 nearly straightforward, but . . .

[Mick F]

All I can say to you, is that my system works ............... and works very well.
Campag Mediun cage works with a total capacity of 53-30 + 30-12 = 41

Two things:
1. The front difference is all to do with the size differences of bigger ring and the smaller ring, AND also to do with the middle ring because possibly the front mech inner plate may touch the middle ring between the outer and inner.

2. The rear mech cage takes up the slack as the chain copes with the chainring size differences and the cassette tooth differences. The parallelogram geometry of the rear mech also has to cope with the max of the cassette.

My above arrangement works. Absolutely and positively.

[Graham]

Thanks Mick.

Before doing anything else, I'm going to have a poke around with the pivots and springs on the Racing-T to see if this invokes some self-healing.

[tippo12]

If you buy the 10sp long cage mech it will all work fine beyond the range you describe.
I have been running two bikes on identical set ups for 10 years plus , one bike lives in France at a place out there.
Record 10sp triple with 53/42/24 (stainless steel granny by engagemnet rings so no chain suck even with 10sp.) on to 13-29 with long cage record rear mech.
I use a deda dog fang on both bikes to stop the otherwise inevitable drop off the granny when changing down into it, otherwise it works flawlessly.
The chain just clears the bottom of the front mech cage on the 4 biggest sprockets, and will just stretch round 53-29, although I would never use it on those two.
This setup has enabled me to keep riding, even in the alps, for a few extra years but only today I saw a surgeon who will be operating on my knee shortly (osteotomy) to try and give me a few more years - that 24 T granny make ALL the difference.

[Graham]

tippo12,

Best of luck with the knee op.

Thank you for this additional information.
My ideal solution would be to buy a new long cage mech which would permit the possibility of lower gears than the current setup.
Thus some future proofing.
At present, I can only find Campag Long cage mechs for far more money than I am prepared to pay.
I'll be waiting for an extraordinary discount from somewhere before I purchase one.

[Brucey]

it might be worth trying a shimano Tiagra RD-4700-GS. This uses a 'new' (new to shimano) shift ratio that is within a gnat's wotsit of the campag shift ratio, i.e. it may be plug and play, and even if it isn't, it might require just a tiny tweak of the cable clamp screw to make it work OK.

Such mechs can be had for south of £25 so it isn't an expensive experiment to try. The capacity is up to 32T max sprocket and 41T total capacity on a triple.

hth

cheers

[Graham]

Thanks for that Brucey. Probably worth a try to get the bike back into action.

Do you have the number for the shift ratio and/or cable pull for the RD-4700-GS ?
( It seems to be far easier to get the important facts about Shimano products, but I have not found that one. )

I will probably open up another topic on why clamping the cable in a different position changes the shifting characteristics.
I realise that I have never really understood this - just accepted it as true, but not really relevant to me [ so far ].

[Brucey]

it has been discussed here

http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=136232 and here

http://forum.cyclinguk.org/viewtopic.php?f=5&t=104359

in fact the suggestion is that if you just bolt it up as per, the result ought to allow campag 10s shifter + RD4700 (or a shimano 11s road derailleur) to work on a shimano 10s cassette (which has a slightly different spacing to campag 10s cassette).

However no-one has come back to say that they have actually tried it and it works OK, not yet.

If it does work thus, a small tweak to the cable mount (a sort of reverse hubbub, probably using a tab washer, clamping the other side of the pinch bolt, or something like that) would allow the same setup to work OK on a campag cassette.

As to why revising the cable mount position affects the shift ratio; it is all a question of leverage. If you measure the (orthogonal, 'lever') distance from the cable mount to the rear outer pivot of the parallelogram, to a first approximation, %-age changes in that distance also make similar %-age changes in the shift ratio.

Thus (say) 10% shorter 'lever' also increases the shift ratio by about 10%.

cheers

[Graham]

Yep, that looks like a go-er. Thanks

[Graham]

. . . but chickened-out in the end and bought a "Triple Comp" LONG cage @ £83

This one glides up onto the 30t sprocket without hesitation and has acceptable wrap&extend on all chainrings.

All looking good except having to re-add to two pairs of links that I removed from the 10-speed chain. I'll be watching out for trouble with them as reconstructing with an old link extractor is probably not advisable.

New one fitted : old one below it

[Mick F]

1. Where did you find the Comp rear mech? I thought I'd bought the last one anywhere!
2. In order to lengthen your chain, use two power links and as many spare links as you need.

I have some short lengths "cut" off from the chains as Campag chains come in 114 links. I only need 110 for Mercian.
Also, as chains wear, I keep the old ones, so all I need to do is take a couple or three off one to use as a "bridge".

My Moulton came with 114 links but really needed 116, and as I've fitted a wider cassette and a bigger outer chainring, I've upped it to 118 links. The main chain is Wiperman Connex, but Campag Chorus links plus KMC Missing Links all seem to match up perfectly. All works well with no issues.

[Graham]

Hi Mick,

The lucky strike was http://www.paulmilnescycles.com/

Thanks for the tips on the 10-sp chain. Still very wary - definitely different to 8-sp chains . I always carry around a link extractor.