MTB Chainset on road??

[mill4six]

I'm remembering a pub conversation with some friends, recently departed for a 6 month fully loaded tour of new Zealand. I asked about their bikes and they described a bodge a using 3x square taper MTB chainset with a double road shifter. They are using only the inner 2 rings and it seems the cable pull works out. All this to get lots of low cogs for dragging luggage up mountains. Since this was a pub converation I thought it best to run it past you guys before I start building my Kaffenback 2. Thanks in advance..

[531colin]

http://www.spacycles.co.uk/m2b0s109p3383/SPA-CYCLES-TD-2-Super-Compact-Chainset-with-Zicral-Rings

[meic]

You generally need a specific triple front deraileur on triples because of the large difference in size between the middle and outer rings.
If you dont have an outer ring in place or it is very near in size to the middle ring then you dont need a triple derailleur and will often need a double deraileur instead so that you can get the cage low enough to stop the chain flying off where there is no longer a big ring to protect it.

When I replaced my son's 28 38 48 with a 28 38 44 (or something like that) the Sora triple wouldnt work with it set correctly according to the outer ring but the double derailleur worked fine.

[mill4six]

Colin, that's the exact one they were talking about. Thanks.

[531colin]

Colin, that's the exact one they were talking about. Thanks.

I have used a 24/40T one of those with an 11 sp 105 F. mech., and I couldn't fault it, except thats a big percentage difference between the rings, although its still the magic 16 teeth.
If you look at a road triple mech. they have a deep backplate, so you need a particular difference between middle and big rings, or the backplate fouls on the middle ring. Road doubles don't have the deep backplate, so I don't know why 16T difference is specified......?......but in any case, I wanted the 24 for the low gears, and even I need some high-ish gears, so I didn't pursue it further.

[mill4six]

So are you using a double or triple mech/shifter with it?

[531colin]

So are you using a double or triple mech/shifter with it?

11sp 105 with hydraulic cylinder for disc brake....... only available as double shifter and mech., as far as i know(!) .....bit modern stuff for me.

Now that i re-read Meic's post, he is saying the same thing, but a different way round......I think!

[mattsccm]

One bike runs a complete SRAM set up with road double shifters and a 28/42 MTB chain set with road mechs. Fine. Did the same with Campag on a MTB triple with the outer ring binned. Fine