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 Post subject: XC pro thumbies
PostPosted: Fri Nov 16, 2012 12:55 pm 
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I've found a few threads on these, but am still a bit unsure... will the 7/8 speed version index well with a shimano 8s drivetrain (standard 8s cassette, XT M739 rear mech) ?

I just found some, which are labelled "F8 F7 --- 8 7". According to mombat, the 7/8 speed thumbies were first available in 1993.

Does anyone know the cable pull of suntour levers? does it match shimano cable pull from the mid 90s? I know that in 95 suntour came out with some parts that were "shimano compatible" - does that mean that parts from previous years aren't?

thanks!


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PostPosted: Fri Nov 16, 2012 2:06 pm 
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I Used them on a suntour/shimano build and worked ok, I only used them on friction tho which still had a bit of indexing feel to it. Excellent tumbies tho far better than shimnos offerings.


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PostPosted: Fri Nov 16, 2012 2:21 pm 
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Thanks. if I can get them to work, then I'd want to use them indexed with 8 speed. I've been checking sheldon's spacing cribsheet, and I can't see why they won't work:

shimano 7s has 5.0mm c-c between sprockets, while shimano 8s has 4.8mm. suntour 8s has a mixture of 4.8 and 5.0mm. since shimano 7 and 8 systems generally work well together, I see no reason why the xc pros won't work well with a shimano cassette.

I think I've got a couple of shimano 8s cassettes (road ratios, but the spacing is the same) so I'll give it a go and see what happens!


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PostPosted: Fri Nov 16, 2012 2:24 pm 
retrobike rider
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foz wrote:
Thanks. if I can get them to work, then I'd want to use them indexed with 8 speed. I've been checking sheldon's spacing cribsheet, and I can't see why they won't work:

shimano 7s has 5.0mm c-c between sprockets, while shimano 8s has 4.8mm. suntour 8s has a mixture of 4.8 and 5.0mm. since shimano 7 and 8 systems generally work well together, I see no reason why the xc pros won't work well with a shimano cassette.

I think I've got a couple of shimano 8s cassettes (road ratios, but the spacing is the same) so I'll give it a go and see what happens!


I'd be interested to see if you can get this to work as i am contemplating going down this route with Suntour thumbies, i might however try and source a Suntour rear mech but will no doubt be a Shimano or Shimano derivative cassette :)


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PostPosted: Fri Nov 16, 2012 2:26 pm 
retrobike rider
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I have a set of XC expert shifters with XT mechs, the back index’s well, once set up.


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 Post subject:
PostPosted: Fri Nov 16, 2012 2:37 pm 
Gold Trader / MacRetro / PoTM Winnner
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I've got Pro paired with M950 casette and XT mech. Works well, very accurate indexing.


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PostPosted: Fri Nov 16, 2012 2:41 pm 
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I don't think the choice of mech will have much to do with it, assuming the cable pull is the same per click with shimano and suntour systems. Since the suntour cassette has two different spacings, I imagine the thumbies will pull a different amount of cable, depending on the position they're in. The difference is the same as between shimano 7 and 8s - 0.2mm per click. I think the floating jockey in shimano mechs should eliminate this difference and allow for decent shifting, although intial setup might be a bit trickier.

I've seen a few threads now where people hace used suntour thumbies on otherwise shimano drivetrains without problem, and I think even som manufactureres (kona?) were speccing this setup onthe bikes BITD.

I might get chance to set it up this weekend, but can't ride it until I get my front brake :(

I'll report back once I get everything working (or not!)


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PostPosted: Fri Nov 16, 2012 2:42 pm 
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thanks Radoslaw, that sounds very promising!


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 Post subject:
PostPosted: Fri Nov 16, 2012 3:28 pm 
retrobike rider
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Yes it'll work as you have the 8sp version.
given the vaugeness of the indexing anyway compared to ratcheted styles like rapidfire. All that the index is is a ball bearing making a clicking sound feel in a hole.

The difference isn't so much the cable pull put the levers throw itself between the xc and xt thumbies.
Go on do it, many have many did.


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PostPosted: Fri Nov 16, 2012 5:04 pm 
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Ridden this way for years, shimano mechs and suntour Thumbies. Works perfectly.

Indeed, it was the higher-end Kona models that came with these and shimano mechs for a few years; Kiluea ^ if I recall?


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