Looking to get some low gears and I see there is a nice fc-t6010 crank in the Shimano T6000 line that would fit the bill. Its 26-36-48t, Hollowtech II but has 50mm chainline. Im on Tiagra 4700 and the triple FD in 4700 is made for 45mm chainline. I suspect it would not would work with that crank, for that reason. There is a FD in the T6000 line called FD-T6000-H-3 that would fit my frame and the crank, but would it work with the 4700 raod tripple brifter?

Different cable pull.

give it a try , report back..

OTOH, a friction bar end shifter is quite adaptable..

Nope. The cable pull ratio of Shimano mountain bike derailleurs isn't compatible with road shifters.

But here's an idea if your derailleur won't swing wide enough to accommodate the crankset: If your frame doesn't have an integral braze-on mount for the front derailleur, you can try using SRAM's 'wide spacing' braze-on adapter to position a Tiagra 4700 triple braze-on front derailleur a few more millimeters outboard.

SRAM Wide Spacing Braze-On Adapter | Jenson USA

You'll still have a mismatch between the crankset's chainring size and the ring sizes the derailleur cage was sculpted to fit, but hopefully not severe enough to prevent it from working. IRD's Alpina-D derailleur would fix the ring mismatch, and it's designed to work with road STI levers, but not the most recent STI levers. Shimano changed the derailleur geometry and cable pull ratio between Tiagra 4600 and 4700.

OK? I suspected that, but could only find info for the rear DR.

Do you know of a cable pull converter that would work or an other solution?

Yes thanks. The 4700 is a bit of an odd ball. Its very annoying Shimano cant keep cable pull consistent or just make a drop bar brifter for the T6000 series. The wide bracket seem like a good idea, but the I need to figure out if the chain ring spacing is the same as on the 4700 triple crank.

As said abive^bar end shifter, take the shift cable out of the brifter, continue to use it as the brake lever..

Im not too interested in friction shifting, but yeah, if its the only solution, I consider it an option.

I see no one has responded negatively to your assumption that the Tiagra FD wont reach. So unless someone says they tried it an doesn't work, why not try it and find if you can adjust it enough to reach the large chainring.

On a 3 x 9 touring bike, I am running an Utegra FD designed for 2 rings (FD-6500). Its designed for 53/42, 53/39, or 52/39 rings, but I am using it with 46T/38T/24T triple rings. I am using a Tiagra triple crankset with a published 45 mm chainline, but the measured chainline to the large ring is about 52 mm and I think I still have some adjustment left on the limit screw. You may have the reach you need (wont know unless you try it).

You are right. I should measure. Do you have any idea how far out the outer ring is on the before mentioned crank?

This going on a road bike? Not only is cable pull a problem...but so is BB compatibility and chainstay clearance. Given that you're starting with a bike built for a roadie triple, this project may work....but the BB will probably need shimmed to 73,mm specification.

When you say "before mentioned crank" I assume you are asking about the FC-T6010. I don't have one so don't know exactly but based on typical spacing between chainrings for 9 speed triples (about 6 mm), the chainline to the outer ring would be about 56 mm (50 + 6). I did measure the chainline to the outer ring on my touring bike equipped with a 9 speed triple XT crankset (FC-M770), the distance to the outer ring measured about 55 mm. I think the FC-M770 and the FC-T6010 are very similar.

use a road FD , then . the cage arc will not be the best look, but they and the brifter are integrated , the I in STI..

I take those chainline numbers as more of an advisory than a hard and fast number. Before you go abandoning anything (yea, the mountain front derailer won't work what the STI), try fiddling with the spacers on the bottom bracket. A thinner spacer on the driveside or removal of the space will tuck the crank inboard and may get you the distance you need. You probably won't have any issue with the crank hitting a road bike frame. It's a least worth an experiment and, since the Hollowtech cranks are simple to work on, it's something easy to try.

I've done it on a couple of bikes and it has worked for me.