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Replacing front mech on compact flat bar roadie ...

KangaKanga Posts: 131
edited August 2009 in Workshop
The cage on my clamp on front mech has cracked, so needs to be replaced. It's an Spesh Sirrus with Shimano 440 8 speed flat bar shifter setup on a compact chainset. The LBS insists they can replace it with a standard Tiagra double front mech, but I've read elsewhere that the 440 kit is MTB indexing and the 440 shifters won't work properly with the road mech. LBS mechanic assures me not to trust anything I read on the web, but it's been more reliable than a string of LBSs over the years.

This is the 9 speed version http://www.parker-international.co.uk/7407/Shimano-R440-9sp-Flat-Bar-Front-Mech.html

Other thead on 440/Tiagra issues http://www.bikeforums.net/archive/index.php/t-187886.html

Help !

Posts

  • bicebice Posts: 772
    I won't read the other threads, but indexing is not really an issue with a front mech and you can mix them up quite promiscuously, so long as they're the right size. On the inner ring, the mech is at rest on the L limit screw and then you are just tightening the cable for the middle and more onto the outer H limit for the larger outer. Even simpler with a double.

    I am not one of the 'trusty LBS school', but the mechanic is probably right on this one.
  • KangaKanga Posts: 131
    Thx bice :)
    The front 'indexing' issue according to the CTC is that "mountain-bike shifters pull 19.5mm of cable across a triple, whereas road equipment does the same with only 13.5mm. So a road shifter pulls only 69% of the cable needed to index a mountain-bike front mech, and a mountain-bike shifter pulls 44% too much to index a road mech".

    Not changing shifters, so assuming FD's are simple beasts that just respond to cable tension it *should* be OK. The Tiagra and 440 FD specs are the same on the Shimano website. Shimano and other sites stress the 440 shifters are only compatible with the 400 FD, but not the reverse, presumably so peeps dont stick on 440 shifters on their MTBs and get the indexing problem. Shouldn't mean they won't work with other road FDs.

    Probably just being paranoid (and ignorant) but the sales bod had no clue and the mechanic was less than convincing ...
  • maddog 2maddog 2 Posts: 8,114
    a road mech will be fine, if you're running a double/compact setup. I've run allsorts of Shimano mechs with the R440 shifter and not had a problem.

    Basically the R440 shifters pull a tad more cable that a road STI, but your limit screws on the mech sort all that out, and anyone with basic setup knowledge should be able to figure it out.

    If you're on a triple then I'm not 100% sure and the 440FD may be the best option.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • KangaKanga Posts: 131
    Thanks MD2, it's a 50/34 compact so fingers crossed :lol:
  • maddog 2maddog 2 Posts: 8,114
    just set up click 3 on the big ring,

    then use the limit screw on the mech to stop the mech overshifting slightly when it drops down onto the 34t (click 2)

    Click 1 is redundant

    Shimano double FDs are fine but you can also use Campag's CT mechs if you tweak the cable routing slightly, which are even better. PM me if you want to know how to do it.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
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