Front Derailleur cable pull ratios - 11sp 105 R7000 road STI, Deore XT T8000 triple FD

[wafter]

I want to mate these two together for reasons I won't bore the forum with. The shifter is for a double FD, so I'm going to pull apart a dead one to see if it can be modded to shift a triple.

Assuming this is even possible I understand from internet research that the cable pull ratios for 11sp road and MTB are "wildly different" - can anyone put any numbers on how much cable is tugged by either of these setups please? I have access to the 105 gear so can measure that for myself, but have no appropriate MTB parts so am in the dark with this one.

Any reliable numbers gratefully received, ta!

 

[dan28]

i dont know the answer
but would be easier to use say an stx 3 speed shifter with a triple speed front mech

 

[wafter]

i dont know the answer
but would be easier to use say an stx 3 speed shifter with a triple speed front mech

Thanks and probably; the problem is that I want a 3x11 setup with hydro disks and STIs, but no such setup is available off the shelf.

I had a proper look inside an R7000 shifter recently with a view to modding one and it was.... intimidating..

 

[ishaw]

There was a time road triple shifters existed. Maybe it's possible to find one and see if the internals can be transplanted into your stis?

 

[dan28]

I think your over thinking
You want hydro discs so I m assuming the shifters are part of the brake lever ?
So maybe use a matchmaker mount
Or can the shifter be removed/ cut off the brake lever
Then just mount an older 3 speed sti shifter
Put a pic up of what you have

 

[wafter]

There was a time road triple shifters existed. Maybe it's possible to find one and see if the internals can be transplanted into your stis?

Thanks - I did consider this but think it's highly unlikely that bits would be compatable. The only groupset I can find that contains both hydro and triple shifters is Tiagra 4700 (2x10, 3x10 mech, 2x10 hydro) and the only thing that appears similar between the mech and hydro shifters is the name.

I would be very happy to investigate this route but sadly it seems that Shimano don't offer parts diagrams down to this level of detail for their STI (nor parts I suspect) and I can't afford to buy one of each to pull to bits!

I think your over thinking
You want hydro discs so I m assuming the shifters are part of the brake lever ?
So maybe use a matchmaker mount
Or can the shifter be removed/ cut off the brake lever
Then just mount an older 3 speed sti shifter
Put a pic up of what you have

I'm not really sure what you're suggesting - I have R7000 105 on the bike currently which is 2x11 with hydro discs (and yes, STIs so brakes and shifters are integrated)....

 

[bikeworkshop]

If you want a triple on the front, you need 3 positions on the sti lever (as well as the deep cage on the f.mech)

I'm pretty sure shimano haven't made a hydro dropbar triple left, and I'm confident the gear assembly inside the lever isn't exchangeable between a cable and a hydro brake lever assembly.

This would mean you could mount a separate gear lever, like a barend shifter, or you could go double

- the range available on a modern compact double combined with wide ratio on the back spelled the demise of the triple chainset for most applications.

We set up a couple of world tour bikes recently with 30-46 double onto 11-42 cassettes, although none of the original road components "survived" the transplant - worked brilliantly.

Walking pace 1st gear, road speed top.

Not cheap though because you can't mix and match much.

 

[wafter]

If you want a triple on the front, you need 3 positions on the sti lever (as well as the deep cage on the f.mech)

I'm pretty sure shimano haven't made a hydro dropbar triple left, and I'm confident the gear assembly inside the lever isn't exchangeable between a cable and a hydro brake lever assembly.

This would mean you could mount a separate gear lever, like a barend shifter, or you could go double

- the range available on a modern compact double combined with wide ratio on the back spelled the demise of the triple chainset for most applications.

We set up a couple of world tour bikes recently with 30-46 double onto 11-42 cassettes, although none of the original road components "survived" the transplant - worked brilliantly.

Walking pace 1st gear, road speed top.

Not cheap though because you can't mix and match much.

Thanks for that really insightful response - reinforces a lot of what I've already found / thought.

Agree about the lack of hydro triple left; sadly.. and I feel you're probably correct about parts interchangeability too although I can't confirm from experience.

I could certainly use a separate gear lever, but that wouldn't achieve the desired outcome. The irony is I have this bike with hydro 2x11 STIs but prefer the gearing and crank ergonomics (wider Q) of my other, far less posh ulility hack with 3x9 and bar-end shifters.

IMO the widespread death of triples is criminal as they can be so good for both range and user experience. The 48/36/26 x 11-34 setup on the hack suits me perfectly; the middle ring is used 99% of the time meaning nice easy rear-shifting only but it's great to know I have really low as well as higher available should it be required. Conversely on the 50/34 x 11-34 on the higher-end bike I'm constantly chopping between front chainrings as ideally I want to be somewhere in the middle.

I had considered a sub-compact but really this would still be sub-optimal (too high at the high end) - seems the closest I could get would be the GRX 600 46/30 (is this what you were using?) although this still leaves the Q-factor problem and I'm reluctant to use pedal spacers for various reasons. I think an ideal double for me personally would be something like a 42/28 or similar; however this seems to be a black spot in terms of what's available. Some of the less mainstream brands do see to cater a little for such small sub-compacts, but then you potentially run into compatability and aesthetic issues...

Granted Shimano do still offer one or two triples although have really destroyed compatability with thier disperate range of pull ratios, lack of range in their STIs and other compatability issues.

It seems that the number of speeds the STIs are capable of shifting is determined by at least three components - a notched "gear" that's actuated by a pawl controlled by the levers, a moving stop that rotates with this gear and a static pressed steel stop that limits the travel of its moving counterpart.

I'd hoped that I might be able to mod / replace what's there to add an extra notch (while potentially also altering the cable pull ratio, depending on what's required by the FD) however at least two of the parts look like hardened steel, so modifying / replacing them is probably non-viable with the facilities I have at my disposal

 

[bikeworkshop]

Thanks for that really insightful response - reinforces a lot of what I've already found / thought.

Agree about the lack of hydro triple left; sadly.. and I feel you're probably correct about parts interchangeability too although I can't confirm from experience.

I could certainly use a separate gear lever, but that wouldn't achieve the desired outcome. The irony is I have this bike with hydro 2x11 STIs but prefer the gearing and crank ergonomics (wider Q) of my other, far less posh ulility hack with 3x9 and bar-end shifters.

IMO the widespread death of triples is criminal as they can be so good for both range and user experience. The 48/36/26 x 11-34 setup on the hack suits me perfectly; the middle ring is used 99% of the time meaning nice easy rear-shifting only but it's great to know I have really low as well as higher available should it be required. Conversely on the 50/34 x 11-34 on the higher-end bike I'm constantly chopping between front chainrings as ideally I want to be somewhere in the middle.

I had considered a sub-compact but really this would still be sub-optimal (too high at the high end) - seems the closest I could get would be the GRX 600 46/30 (is this what you were using?) although this still leaves the Q-factor problem and I'm reluctant to use pedal spacers for various reasons. I think an ideal double for me personally would be something like a 42/28 or similar; however this seems to be a black spot in terms of what's available. Some of the less mainstream brands do see to cater a little for such small sub-compacts, but then you potentially run into compatability and aesthetic issues...

Granted Shimano do still offer one or two triples although have really destroyed compatability with thier disperate range of pull ratios, lack of range in their STIs and other compatability issues.

It seems modifying / replacing them is probably non-viable with the facilities I have at my disposal

If it's possible, someone will have probably already done it and you'd find it online

I wondered if you could set up a double for the mid/large ring, but run the cable through an inline quick release, so in the middle gear, you could release some cable with the QR, dropping the (triple) front mech onto the inner gear stop set up to align with the small front ring.

Smcb90:

Designed for brake cable obvs but could be fitted up by the bar - same size end caps.

As an aside, many regular cyclists used to a front triple find the change to double compact shifting timing annoying at first, but nearly everyone forgets about it after getting used to 2x11.

Maximum angles on 3x11 bring new problems, so I think shimano & others decided to kick the 3x into touch and design rear mechs that could handle dinner plates to get back the overall 400%+ of ( touring) range.

We've done front doubles with custom rings for a lot of bikes - you can push it to 16t difference, maybe more, just choose your starting ratios.
1st gear sprocket on the cassette defines your choices though - and this in turn is determined by the choice of derailleur.
Modern long cage road 11s (with the drop hanger)
will do 40t, and grx can do 42, and maybe more -
Chainstay length and chainline can complicate matters!

It's easy for us to see what's possible as we have every derailleur and cassette option on the shelf, so can swap everything out to find the limit.

It's far harder for an individual to get right as you only know what works to your own expectation by actually trying it, as this is stepping out of the Shimano Playbook.

 

[dan28]

ahh i was thinking about mtb shifters where the brake lever an shifter are horizontal
IF you could find a suitable bar clamp i bet you rustle something up using a draw bolt from a canti brake (it has a hole through to clamp the brake block) an mount an mtb sti shifter to it ,it wouldnt look pretty but it would work