Do shimano sti shift levers work with DX cranksets?

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Tizme
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Do shimano sti shift levers work with DX cranksets?

Postby Tizme » 15 Jan 2017, 6:32pm

Originally I was looking at a Specialised AWOL frame to build up as a tourer, with the aim of a LEJOGLE, (solo camping, taking around 25-30 days). After a bit of research I decided on a Tiagra 4700 (10 speed) set up (50-39-30 on the front with an 11-32 cassette and medium cage rear dérailleur). All bought and ready to go, but no frame available, so I finally went for a Genesis Vagabond frame. Then came the disaster, the Vagabond will not take the chainset! Talking to Genesis it will take a 48-36-26 trekking one, so I am looking at this:
https://www.rosebikes.co.uk/article/shi ... aid:670656

Ideally I want to keep all the bits I've already bought (and I prefer STI levers) but as all but the chainset is still in the packaging CRC may take it all back, especially if I just order replacement parts.

However, and after all that, can anyone tell me if it will work, or will I need to drop to 9-speed to get the shifters to work, or is there a better option?

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531colin
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Re: Do shimano sti shift levers work with DX cranksets?

Postby 531colin » 15 Jan 2017, 6:54pm

Tizme wrote:Originally I was looking at a Specialised AWOL frame to build up as a tourer, with the aim of a LEJOGLE, (solo camping, taking around 25-30 days). After a bit of research I decided on a Tiagra 4700 (10 speed) set up (50-39-30 on the front with an 11-32 cassette and medium cage rear dérailleur). All bought and ready to go, but no frame available, so I finally went for a Genesis Vagabond frame. Then came the disaster, the Vagabond will not take the chainset! Talking to Genesis it will take a 48-36-26 trekking one, so I am looking at this:
https://www.rosebikes.co.uk/article/shi ... aid:670656

Ideally I want to keep all the bits I've already bought (and I prefer STI levers) but as all but the chainset is still in the packaging CRC may take it all back, especially if I just order replacement parts.

However, and after all that, can anyone tell me if it will work, or will I need to drop to 9-speed to get the shifters to work, or is there a better option?


Why won't the Vagabond take the chainset?
Road chainline (Tiagra) is closer in to the frame than MTB. If the Vagabond needs an MTB chainline to stop the chainrings scraping the chainstay, then Tiagra F. mech. won't line up with the MTB chainset.....and an MTB F. mech. won't index with road STIs

Valbrona
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Re: Do shimano sti shift levers work with DX cranksets?

Postby Valbrona » 16 Jan 2017, 3:41am

Yeah, why won't a Tiagra triple crankset fit? If it does, it will give road chainline as per Colin's post. So yes, why not use a different crankset that gives a more suitable chainline.

Note that a triple 105/5703 front derailleur will work with a 36/48 triple crankset but an Ultegra/6703 FD won't - more of a jump needed. Different cage. Been there, done that.

Dunna know what the cage is like on a Tiagra triple FD, but the tech docs will indicate what chainrings it will work with.
I should coco.

Tizme
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Re: Do shimano sti shift levers work with DX cranksets?

Postby Tizme » 16 Jan 2017, 12:32pm

I can assure you the Tiagra 4703 triple will NOT fit. I've had to patch up the chipped paint on the chainstay! :x Again, Genesis say a 48-36-26 will just fit. :( Okay, perhaps I'm doing it all wrong, but this is my first bike build, I want to at least build most of it myself, so if I do have a problem on my trip I might just be able to sort it out! The LEJOGLE (already done a JOGLE) is a test for a Santander back to UK Bucket List trip (but don't mention it to SWMBO :) )
So what I am looking for is something that will work with 10-speed Tiagra STI's (so I don't have to buy even more kit). If needs be I will go down to a double on the front, but as I am looking at touring fully laden (albeit on roads/canal paths - not too far off the beaten track) I want something that will get me up the hills.

Norman H
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Re: Do shimano sti shift levers work with DX cranksets?

Postby Norman H » 16 Jan 2017, 1:42pm

Presumably the Vagabond is made for the smaller rings of a mtb chainset. The problem with external BB mtb chainsets is that they come with very limited scope to adjust the chainline and the resultant mtb chainline will not play well with your road STI's and front changer. You might get away with a square taper mtb chainset which would give more scope for adjustment. Something like this from Spa maybe but I don't know if it would work with 10 speed chain.

It's not available in 48,38,26 but you may well have to go smaller than this in order to shift the drive side crank far enough inboard to achieve a road chainline. I would talk to Spa as they will be best placed to advise a suitable axle length for your desired chainline

The other alternative is a 5arm 110/74BCD square taper chainset, also available from Spa.

Edit:-

I see that Spa recommend a 107mm JIS axle for their 104BCD chainset. I don't think that you will be able to go smaller than that unless you can make an iso taper work. So that looks like a non starter.

Tizme
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Re: Do shimano sti shift levers work with DX cranksets?

Postby Tizme » 16 Jan 2017, 4:07pm

Thank you for that Norman :D
I did wonder about a square taper, I was looking at this from Spa: http://www.spacycles.co.uk/m2b0s109p3/S ... act-Triple,
this requires a Stronglight JP400 110mm bottom bracket, so perhaps that will fit?

Norman H
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Re: Do shimano sti shift levers work with DX cranksets?

Postby Norman H » 16 Jan 2017, 4:58pm

Yes I think that should work but nothing is certain in this world and a certain amount of trial and error may be involved. That's the 5 armed option that I mentioned upthread. Spa also do their own brand version (XD2) or (TD2 with Zicral chainrings), which is better value I think.

You will need to select a BB axle length to give you as close to a road chainline as you can get, 110mm for XD2 or 113 for TD2 I believe (but check this with Spa before purchase) You will also need to select your chainrings with a regard to them conflicting with the chainstay.

Which of the three chainrings on your present set up is hitting the chainstay?

You may not be able to manage the 48,36,26 that Genesis say is possible because presumably that is with a mtb chainline.

By the way I prefer Shimano UN 55 BB to the Stonglight JP400

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531colin
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Re: Do shimano sti shift levers work with DX cranksets?

Postby 531colin » 16 Jan 2017, 5:08pm

Tizme wrote:I can assure you the Tiagra 4703 triple will NOT fit. I've had to patch up the chipped paint on the chainstay! :x Again, Genesis say a 48-36-26 will just fit. :( Okay, perhaps I'm doing it all wrong, but this is my first bike build, I want to at least build most of it myself, so if I do have a problem on my trip I might just be able to sort it out! The LEJOGLE (already done a JOGLE) is a test for a Santander back to UK Bucket List trip (but don't mention it to SWMBO :) )
So what I am looking for is something that will work with 10-speed Tiagra STI's (so I don't have to buy even more kit). If needs be I will go down to a double on the front, but as I am looking at touring fully laden (albeit on roads/canal paths - not too far off the beaten track) I want something that will get me up the hills.


Perhaps if you had told us in the first place that the Tiagra chainset fouled on the chainstay, we could have saved a bit of time and excitement?
Am I right in thinking that the 30T road inner chainring fouls on the chainstay?
And Genesis tell you that a 26 will clear the chainstay?
Now the difference in diameter between a 26T and a 30T is not very much.
So, again, DOES THE DEORE CHAINSET FIT BECAUSE THE INNER RING IS SMALLER, OR IS IT BECAUSE ITS AN MTB CHAINLINE?
Also again, if you use an MTB chainline, then you can't use a road F mech., because it won't reach, and if you use an MTB front mech. you can't use road STIs because the cable pull is different.
Various people have linked 2 Spa chainsets, one 4 bolt and one Stronglight Impact. If you fit these with the Spa recommended bottom brackets, they will be ROAD chainline.
This one http://www.spacycles.co.uk/m2b0s109p3052/SPA-CYCLES-TD-2-Touring-Triple-Chainset-with-Zicral-Rings is also road chainline, and works well with 10 speed.
I see Norman posted while I was writing that. Norman and me are saying the same thing......EXCEPT that I don't think you know what chainline you are after, and Spa can't possibly know, as they haven't got your frame in front of them.
Genesis should be able to answer the question "will a triple chainset with a road chainline fit with a 24T inner ring?"
I say 24T because thats the smallest that will fit the 5 arm chainset. The 4 arm chainset goes down to 22T inner, BUT there are fewer rings available, and you need to match the outer ring to inner ring tooth difference that your front mech. is designed for.

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andrew_s
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Re: Do shimano sti shift levers work with DX cranksets?

Postby andrew_s » 16 Jan 2017, 8:53pm

The off the peg Vagabond is advertised as a "Monstercross" bike, comes with 29x2.1 inch tyres (700 x 55), and will consequently use an MTB chainline. It uses MTB front and rear mechs, and uses bar-end shifters.

The line of least resistance is to follow suit.


I have had an XT front mech working well with Ultegra STI, during the 9 speed era, but it was a bit of a nightmare to get set up, so once it was working it was a case of don't touch unless absolutely necessary, like a broken cable.
I've also used Ergolevers with an XT front mech, the front not being indexed the same as STI.
Note that I use square taper, and run the chainset a little closer in than standard because most of my riding is on the large chainring.

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531colin
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Re: Do shimano sti shift levers work with DX cranksets?

Postby 531colin » 16 Jan 2017, 10:37pm

Image

Thinking on, it is possible to use an eccentric shim to re-position a F. mech. to suit a different chainline.
Picture is a home-made shim, and I'm using it to get an MTB F. mech. to a road chainline. Should work similarly the other way round, I would guess.
SJS sell one such shim.

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Re: Do shimano sti shift levers work with DX cranksets?

Postby Norman H » 17 Jan 2017, 6:36am

andrew_s wrote:
The line of least resistance is to follow suit.


I think Andrew may have a point. Trying to run a road chainline on that frame may be a bit ambitious. If you had the parts to hand in your spares box you could suck it and see but if you have to purchase them in order to experiment, you could be embarking on a costly exercise. You really need to talk to Genesis to determine what rings can be accommodated at a road triple chainline.

markfh
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Re: Do shimano sti shift levers work with DX cranksets?

Postby markfh » 17 Jan 2017, 9:46am

When you fitted the Tiagra chainset which of the chain rings fouled the chainstay? Reducing the tooth count of a chain ring by 2 teeth reduces it's radius by a fraction over 4mm. By carefully refitting the Tiagra chainset you may be able to estimate how much you need to reduce the tooth count of each of the chainrings in order to clear the chainstay with a reasonable safety margin.

With both the Tiagra chainset and the Deore one, the chainline is determined by the chainset/bottom bracket configuration and the options for "adjusting" it are very limited - see the eccentric shim suggested by 531colin although in your case if you were wanting to use a road front derailleur (Tiagra) with a chainset designed for a MTB chainline the thicker side of the eccentric shim would need to be on the derailleur side of the seat tube. Whether this approach will work with the Tiagra front derailleur you have will depend on what seat tube diameter it is designed for.

If you use a chainset that uses a square taper bottom bracket then you have the option of selecting a different length bottom bracket and using that to adjust the chainline to something between a road chainline (45mm) and MTB chainline (47.5mm or greater). Although a Tiagra triple front derailleur is designed for road chainline it may be possible to adjust it to work with a slightly wider chainline and still shift OK.

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CREPELLO
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Re: Do shimano sti shift levers work with DX cranksets?

Postby CREPELLO » 17 Jan 2017, 10:23am

Looking at a picture of a Vagabond frameset, I think it may be the outer ring that catches the frame. Is it??
Vagabond FS.jpg


I think an eccentric shim, as illustrated above could work (as long as the set tube is steel-28.6mm) with the Tiagra FD.

But looking at the spec for a Dawes Gran Tour, it uses a Tiagra 4603 FD with a Deore triple CS, which suggests any problem is unlikely, at least with this model combination.

Consider which gear ratios are most suitable for the bike's intended purpose, rather than simply choosing a chainset to fit a front mech (or chainline). It so happens that a road chainline is well suited to a touring type machine if you spend large amounts of time on the larger cogs at the back.

reohn2
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Re: Do shimano sti shift levers work with DX cranksets?

Postby reohn2 » 17 Jan 2017, 11:06am

The problems the OP is finding are compound,chainring size,STI's,compatability of front mech with STI.
If STI's are sacrosanct the front mech needs to be a road one,road mechs work with smaller rings than specced.I currently run them with 46/34/24,and have run them with 48/36/26.
If Genesis say the Vagabond will run 48/36/26 the question the OP has to ask himself is,is a 48t big ring big enough at the top end with an 11t top cog?
The eccentric shim will allow a road mech work with STI's.

Personally,I'd go for a Spa's own 48/34/24(to be on the safe side) with a UN54 the right length to give the MTB chainline required.
A 115mm BB gives a 42mm road chainline with Spa's own triple c/set on a 68mm shell,so I'd suggest a longer BB axle to be safe(122.5mm?)though it may work with 118mm depending on clearance between chainstay and chainrings..
The eccentric shim will take care of the mech alignment which of course will be infinite within a given range,but a 34.8mm seatube diameter mech is needed to fit the shim.
It's very doable with those components IMO

EDITED for clarity
Last edited by reohn2 on 17 Jan 2017, 1:26pm, edited 1 time in total.
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willcee
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Re: Do shimano sti shift levers work with DX cranksets?

Postby willcee » 17 Jan 2017, 12:28pm

Interesting contris , however newbies to off grid bike mods are faced with some situations that i cannot comprehend..i meet them weekly, buying starter road bikes to become sunday warriors, that won't take guards, changing or wishing to have chainsets that give them power figs , when they don't race!!!! on machines that won't accept different brackets, getting the wrong bike because it was the one everyone else raved over....so they get themselves into all sorts of handlings.. that's before they realise the true cost of non std builds, and all because they read in a blog or a mate told them or the testers in a mag said so.. off grid mods were never cheap unless you had £ , access to engineering machinery, and some decent hands on cycle building skill.. there's plenty of experience on this forum , all of it depends on the OP's own skill and will to listen to collective advice.. just me ranting.. will