Drop Barred Mountain Bikes - STI Shifters and Front Mechs - What will work?

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Drop Barred Mountain Bikes - STI Shifters and Front Mechs - What will work?

26 posts & 19 voices | Started 1 year ago by MrTall | Latest reply from antigee

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MrTall - Member

I have a Salsa Fargo which i bought recently and it's almost built up (with the help of my friendly LBS).

I'm hoping to run STI 9 speed shifters rather than bar ends (using a deore 48/36/26 chainset) but we could not get a front mech to work properly in the shop on Saturday. A Deore one was no good so we then tried a Road 105 triple which 'mostly' worked but the spacing was not quite good enough and gave a constant rub in the big ring. The simplest solution was to change the BB spacers (68mm shell) to gain an extra 2.5mm but ideally i'd rather keep the BB spaced correctly. Is there a better front mech out there that will have a bit more 'throw'?

I've looked at the picture of Chipp's Fargo from the STW article and he is running STI's with a MTB trekking chainset (XT version rather than Deore) so it must be possible.

Any thoughts? I know there are a few Fargo/Gryphon owners on here - what worked for you? Cheers.

Oh, and if anybody has any older 9 speed STI's in the spare bin in good working order, let me know - ideally 105 or Ultegra. Thanks.

Posted 1 year ago #
carlosg - Member

Try lower down the range than Deore for the front mech (altus/acera) you quite often get 48t big rings on lower end bikes that are still on square taper chainsets. I used an old STX-RC one without problems on my mtb tourer.

Posted 1 year ago #
one_bad_mofo - Member

Lifted from Sheldon Brown, may be of some help...

Cable Attachment (front)
In the case of front derailers, some newer models are designed with a choice of two cable attachment options. If the cable is run on the outside of the anchor bolt, away from the parallelogram pivots, the cage moves less far for a given cable movement. This provides a lighter action, and easier fine trimming.

If the cable is run on the inside of the anchor bolt, toward the parallelogram pivots, the cage moves farther for a given cable movement. This is often necessary to provide correct functioning with indexed shifters.

Posted 1 year ago #
cy - Member

The problem you have isn't the front mech, it's the shifter/crank combo. MTB cranks have a wider 'ring spacing that road triples, so the cable pull on the STI isn't enough to pull the front mech far enough across for your MTB based crankset. The only way to sort it properly using STI's is to go to a road triple.

Posted 1 year ago #
MrTall - Member

Carlos, i thought about that but we checked and the Deore and XT both supposedly have a range up to 48 tooth (SLX was only 44T).

That Sheldon link is also useful, thanks O-B-M.

Cy - thanks - this is what we kind of expected. Just trying to find a road front mech with a bit more throw to see if i can avoid having to swap a brand new chainset. There must be one out there somewhere....

Posted 1 year ago #
antigee - Member

i run STI's with an XT front and XT triple - its not perfect as in very fast shifting but it works and I've been out with people whose gears have shifted a lot worse. think the big cog is a 48
Doesn't always like to drop on to the granny unless i shift rear at same time - guess this reduces chain tension a bit
adjusting cable tension might be an issue - i bodged up an adjuster on the seat tube with an old brake caliper adjuster - should have fitted inline adjusters - also now that rear mechs don't have adjusters
not pretty but gets my knackered knee up some of the local hills albeit slowly and option of drops in headwinds

Posted 1 year ago #
Craggyjim - Member

If what CY says is right could you not pack out the cable clamp area of the Deore derailleur with a couple of small washers. This would effectively increase the lever length and therefore the throw?

Posted 1 year ago #
gert - Member

I have a Fargo running 3x9 with Tiagra STI shifters, 26/36/48 XT cranks and LX front mech.

It did take a while (and all the outward adjustment) to set up so that it would shift up onto the 48, but it is now very smooth when shifting. It requires a firm push of the shifters all the way across for the shift up to 48 though.

There is no chain rub at all, the only issue I have is an occasional jump from the 48 onto the 26 when trying to shift down to the 36, when I'm on a too large cog at the rear.

Posted 1 year ago #
druidh - Member

My Sutra ran 105 shifters and front mech, with a road crankset. Perfect shifting all the time. Given you have a MTB rear mech and MTB cassette ranges, just take advantage of that to get a mahoosive gear spread.

Posted 1 year ago #
kaiser - Member

Cy ...are you 100% sure that mtb and road chainsets have different centre to centre chainring spacing? it's relatively common knowledge that road shifters pull less cable than mtb ones and hence need a road specific front mech or alternative cable clamp position but I wasn't aware the chainring spacing was an issue . Here to learn if that's so !

oh and for the OP ..you may or may not find something helpful here

Posted 1 year ago #
iain1775 - Member

STI Sora shifters with XT mech and Tiagra chainset works fine on my commuter (old Voodoo hardtail), before I switched chainset I had an XT (M760) on there and that was fine too
With both set ups there was some rub on big big and middle rear gears initially but got it sorted pretty easily after a couple of rides by just tweaking the H or L screws

Posted 1 year ago #
kaiser - Member

can't see how you chaps are getting sti road levers to work with mtb front mechs on a triple, as they only pull 69% of the required cable length (if you are clamping the cable in the usual position )........
that's how it used to be anyhow.

Posted 1 year ago #
mattsccm - Member

I have run all sorts of crap as front mechs on triple chainsets. Never a problem except with modern mtb stuff. Currently running an ancient Campag record mech on a Stronglight triple. Perfect. I reckon the spacings of the chainwheels must be wider than modern stuff as at the youngest its 8 speed compatible. Maybe the BB is a touch wide. I tend to run mine as narrow as possible without the inner ring touching the chainstay. Must admit to using Campag shifter which are a bit more flexible in their setup.

Posted 1 year ago #
cynic-al - Member

Must admit to using Campag shifter which are a bit more flexible in their setup

...making your post irrelevant.

Posted 1 year ago #
antigee - Member

can't see how you chaps are getting sti road levers to work with mtb front mechs on a triple, as they only pull 69% of the required cable length (if you are clamping the cable in the usual position )........

not doing anything odd with clamp - yes its not an easy set up has to be spot on and the big ring is at limit of mech move but will drop to granny ok - but not every time/first time - a quick jiggle on rear mech will get it if trying when pressing hard on pedals - top to middle is good chain rub only if granny to small#

69& would suggest won't work but it does might not be as fast and smooth as road riders would like

Posted 1 year ago #
still s8tannorm - Member

Sorry for the slight hijack but would the same problems be present using bar end shifters and mtb mechs/gears?

I ask as I have a special birthday coming up and I'm thinking a Fargo will make a nice present to myself

Cheers
Stuart

Posted 1 year ago #
kaiser - Member

Still think CY may be wrong but awaiting his reply

Posted 1 year ago #
iain1775 - Member

still s8tannorm I had dura-ace bar ends before the STI's (yep I changed my bike around alot experimenting) and they too where fine with XT mech / chainset
But it seems others may disagree as this is supposedly impossible

Posted 1 year ago #
Sam - Member

I'm not 100% certain as I don't tend to use multiple front chainrings and STI shifters myself. However I was under the same impression as Kaiser, that the spacing between the rings was the same (otherwise you'd drop the chain between the rings) but that the actuation ratio of the shifters and mech was different. So in theory a front derailleur designed for a road triple should work, but you say the 105 triple one wouldn't go? The idea of a few washers under the fixing bolt is not a bad one and certainly worth a try.

Personally I like the Campag 10/Shimano 8 speed arrangement and have set this up on a few bikes. Stuart, no, bar ends don't have the same issue as they don't have indexed front shifting. Still need to make sure you use a road triple front derailleur though.

Posted 1 year ago #
paulosoxo - Member

I have this on my uncle John

Ultegra 9spd STI's
XT Rear Mech
Tiagra Front Mech
BB7 Road discs

Works fine, can't see a problem with removing a spacer though, and I'm sure the XT trekking BB's come with half width spacers to fine tune anyhow

Posted 1 year ago #
Steve-Austin - Member

I've run a 105 shifter with an xtr front mech and it all shifted fine across a 3spd mtb chainset.
it was a little fiddly getting it into bottom as it was at the end of the stops. i think i ran it a slight angle..

then i grew some and fitted a double

Posted 1 year ago #
MrTall - Member

Cheers for all the responses so far, lots of useful information (that could be a first for STW?).

I'm told bar end shifters will work with no problems (this is how the Fargo full build bike is set up). Looks like swapping the BB spacers will be the best option although one of the mechanics in the shop has an older LX front shifter which apparently has a bit more pull which we may try first before we go back to the 105/Ultegra front mech option.

I'll point my LBS towards this thread to see if the spacer solutions etc can be attempted.

Posted 1 year ago #
ewangronk - Member

I run a 3 spd tiagra STI shifter with an SLX front mech on my Inbred 29er, originally ran 22/32/44 Stylo crankset, now 22/34/46 rings on the same cranks and all works well, I think maybe the 'trim' that you get with STI shifters helps as if you get a slight bit of rub in a gear combination a wee half shift will move the mech slightly.

Posted 1 year ago #
firestarter - Member

My cx used to be Tiagra shifters and front mech xt rear mech cassette and xt triple chainset duraace chain all ran perfectly

Posted 1 year ago #
fargonz - Member

I'm having the same issue with setting up my bike MTB front rings & xt FD. Doesn't quite pull enough cable to fully clear the big ring.

Will probably go for bar end shifters

This link has pretty comprehensive details about it
http://www.ctc.org.uk/DesktopDefault.aspx?TabID=%204068

Posted 1 year ago #
antigee - Member

a few months down the line and think this may well be correct

Must admit to using Campag shifter which are a bit more flexible in their setup

Posted 1 year ago #