Front derailleur for 26-42 double

[3mn]

Hi,

I need a front derailleur for a double 26-42 double using the inner two positions on one of spa cycles square taper triple chainsets. Bottom pull, 31.8mm clamp. Rear spacing is 135mm so I think I'm aiming for a chainline of 47-48mm (but please let me know if I'm wrong there). Thinking about cx70 derailleur, but can anyone suggest any other options/

Many thanks

David

[Valbrona]

There's the special one from Interlock Racing Design, but I am not sure about it's compatibility with newer STIs.

If you fitted the third chainring life would be so much simpler for you.

[tatanab]

I have a 40/24double where I use a Campag triple which works fine. Photo is not taken square on, so looks a bit gappy at the back. You do not specify, but if you use Shimano stuff the Campag mech probably would not work well with an STI, indeed you do not specify if you use indexing or friction on the front. Just slap on a triple mech and I'm sure you will be fine. Depending on frame geometry a road mech may be best. I have read that Shimano MTB mechs are longer and might foul the chainstay - again, this depends on frame geometry.

[gaz]

IRD is a rebranded Microshift:
http://www.microshift.com.tw/en/product/fd-r52s-bf/

[3mn]

Thanks for your replies - I meant to say friction shift so no compatibility issues there, my main concern was would a road derailleur move far enough out? The microshift one looks good as it says it is designed for max teeth between 36 and 50, but that the chainline is supposed to be 43.5. Is it likely to reach the extra few mm?

[531colin]

Hi,

I need a front derailleur for a double 26-42 double using the inner two positions on one of spa cycles square taper triple chainsets. Bottom pull, 31.8mm clamp. Rear spacing is 135mm so I think I'm aiming for a chainline of 47-48mm (but please let me know if I'm wrong there). Thinking about cx70 derailleur, but can anyone suggest any other options/

Many thanks

David

Errrr.....ask Spa?
You don't say if its this chainset or another one...https://spacycles.co.uk/m2b0s109p3383/SPA-CYCLES-Super-Compact-Chainset-with-Zicral-Rings
When I needed to test the prototype Elan, the boss wanted 105 hydraulic discs on it, and I needed low gears as I was pushing 70.
105 hydraulic takes you to just a double chainset, and the lads built it for me with 24/40T. Thats the regulation 16T difference for Shimano road stuff, and I think they used a 105 (double) front mech.
I tried to make it miss a shift, and I couldn't, so it works. But 24 to 40 is a big percentage change, even though its the regulation 16 T (of course 16 is a smaller percentage of 34 than of 24!)
Road STIs mean the cable pull is right for road front mech., and that means "road" chainline to suit the mech.
Even "road" disc hubs are 135mm OLN, so I guess its still a "road" chainline.

I must say my preference with friction front shift would be for a triple chainset....24/34/46.
Not because of the higher top gear, or even because of the slightly lower bottom gear, but because having a triple avoids the leg-wrenching jump that you get with a double chainset and a small inner ring.

[mattsccm]

SRAM road mechs work happily with 28/42 and I can't see why a 26 wouldn't work. No idea on chainline. One of mine works with a MTB double on EBB and the other uses inner and middle slots on a square tapered MTB triple.