Tiagra 4700 - has anybody................

[MartinC]

..............done any of these things with success?

1.     Run a 4700 2x10 transmission with DA 11 speed bar ends?

2.     Run 4700 STI's with centre pull brakes (Dia Compe GC700's)?

Any experience or thoughts welcome. In theory 1 should be OK with a spare click.  Not sure how 2 will pan out.

[grams]

If you do (1) you’ll just end up with an 11 speed drive train, with the wrong mech movement for 10 speed cassettes.

[MartinC]

Thanks, yes, I didn't think that one through! 

[Cudzoziemiec]

Isn't 4700 the 10-speed group which uses 11-speed pull ratio? In which case 1) should work, albeit obviously with a redundant click at one end.

[grams]

The 4700 rear mech does indeed use the 11 speed pull ratio, but the 4700 shifter uses an oddball cable pull distance per click to make it work with a 10 speed cassette. If you substitute the shifter for something with a different cable pull per click, it won’t work.

[zigzag]

i've heard that 11sp bike kinda works with 10sp cassette, not in all cases, but it's possible to have 7-8 gears out of 10 shifting fine. this is not ideal and only good for emergency use (e.g. in case of damaged 11sp wheel in a race, tour).

[Cudzoziemiec]

I didn't realise it was quite that special. Even for 21st-century Shimano, that is quite obscure – or maybe obscurantist.

[MartinC]

Ummmm.     I'm having a bad hair day (lost -as in misplaced - the dog earlier) but maybe I'm not as confused as I thought.  I think we all agree - 4700 mechs turn 11 speed cable pull int 10 speed cassette spacing - so using an 11 speed (Shimano) Bar End shifter will move the mech correctly across a 10 speed cassette and 1 click beyond.

[bludger]

I can't attest for rear shifting - but I fitted a campag front brifter without any dramas so I expect shifting at the front is fine. Presumably if the bar ends are in friction mode then you'll be onto a winner.

[zigzag]

Ummmm.     I'm having a bad hair day (lost -as in misplaced - the dog earlier) but maybe I'm not as confused as I thought.  I think we all agree - 4700 mechs turn 11 speed cable pull int 10 speed cassette spacing - so using an 11 speed (Shimano) Bar End shifter will move the mech correctly across a 10 speed cassette and 1 click beyond.

not correct. 11sp bar end will move 4700 rear mech for an 11sp cassette.

[grams]

Ummmm.     I'm having a bad hair day (lost -as in misplaced - the dog earlier) but maybe I'm not as confused as I thought.  I think we all agree - 4700 mechs turn 11 speed cable pull int 10 speed cassette spacing - so using an 11 speed (Shimano) Bar End shifter will move the mech correctly across a 10 speed cassette and 1 click beyond.

No, a 4700 rear mech is an 11 speed mech with a different badge. The 10 speed ness is in the cable pull of the 4700 shifter.

[sojournermike]

Ummmm.     I'm having a bad hair day (lost -as in misplaced - the dog earlier) but maybe I'm not as confused as I thought.  I think we all agree - 4700 mechs turn 11 speed cable pull int 10 speed cassette spacing - so using an 11 speed (Shimano) Bar End shifter will move the mech correctly across a 10 speed cassette and 1 click beyond.

not correct. 11sp bar end will move 4700 rear mech for an 11sp cassette.

This. So swap out the cassette for 11 speed at the same time. If the freehub is 10 speed then the 11-34 cassette will fit, but not those with smaller big cogs.

[MartinC]

not correct. 11sp bar end will move 4700 rear mech for an 11sp cassette.

No, a 4700 rear mech is an 11 speed mech with a different badge. The 10 speed ness is in the cable pull of the 4700 shifter.

There are 2 options.  Either the mech movement ratios for 11 speed and 4700 are the same and the shifter cable pull is different or the mech movement ratios are different and the cable pull is the same.  Or, even, both are different!

My, and others, understanding is that it's the second option but I'm not aware of any hard evidence for this and the Shimano compatibility charts don't help either way.  You, clearly, favour the first scenario - can you share the rationale for this?

[MartinC]

Aha!  Shiftmate's charts show and option for Shiftmate 1 to use a 4700 mech with an 11 speed shifter and a 10 speed cassette.  So it confirms what grams and zigzag are saying.  4700 has a cable pull all of it's own.

[sojournermike]

Aha!  Shiftmate's charts show and option for Shiftmate 1 to use a 4700 mech with an 11 speed shifter and a 10 speed cassette.  So it confirms what grams and zigzag are saying.  4700 has a cable pull all of it's own.

Yes, you need a converter to run 11 speed shifters with a 4700 mech to cover a 10 speed cassette, but if you have 11 speed shifters and a 4700 mech you can use it on an 11 speed cassette in the same was as a 5800, 6800 etc. See post 2

https://forums.roadbikereview.com/components-wrenching/tiagra-4700-shifter-pull-ratio-355678.html#post5047477

The pull ratio for 4700 is the same as 11 speed, but the cassette spacing is different between 10 and 11 speed. Hence the shifter controls the mech movement and that has to match the cassette in use.

Also, as noted, if the freehub is 10 speed then the 11-34 11 speed cassette will fit (although the mech may not have sufficient capacity?).

Mike

[MartinC]

The pull ratio for 4700 is the same as 11 speed

An observation not a criticism, all your input is valuable.  It's the common usage of the above that adds to the confusion.  It's the shift ratio (how the mech translates cable pull into lateral jockey wheel movement) that's the same for 4700 and 11 speed not the cable pull.  Pull ratio isn't clear 'cos it could mean the amount of cable pulled per shifter click or the mech's shift ratio.  Life would be easier (for us) if the manufacturers published proper technical specs - but it's not in their interests.

[MartinC]

If anyone's interested Microshift apparently make a down tube lever with Tiagra 4700 cable pull - it's SL-D10B, but I can't find a retailer that sells it.  Not to be confused with the SL-D10 which is standard Shimano road cable pull.

[Brucey]

re shifter compatibility;

4700 RDs indeed have the same shift ratio as 11s 'road' mechs, so various things are possible here. However shimano 'road' 11s cassettes have a 3.74mm spacing and 10s cassettes have a 3.95mm spacing. This all means that if you use an 11s shifter with a 4700RD the mech will move 3.74mm per click not 3.95mm. Some folk would be happy with that, but if the adjustment is 'perfect' in the middle of a 10s cassette it'll be 0.2mm off per click away from the centre until the mech hits the limit screws; IME this is likely to be OK if you have to, but noticeably 'not perfect' otherwise.

  There is also the issue of click spacing at the ends of the travel; 10s has 9 clicks, and clicks 2-8 produce an exact movement. Clicks 1 & 9 have longer cable pulls than normal to ensure that the RD is into the limit screws and that they determine the mech position in the highest and lowest gears.  Thus if you use an 11s shifter you will be using a short pull (either click 2 or click 9) to access one of the extreme gears in a 10s setup and it may not work perfectly.

Re the brakes, ST-4700 has 'New Super SLR' brake cable pull which is considerably longer than older  brakes used, with a lever mechanical advantage (MA) of about 2.5 or 2.75 or so . This will mean that without a travel agent or something, older brake calipers, centre pulls, cantis etc (which are deigned to use  a lever MA of about 4:1)  will be likely to feel 'wooden' and a bit feeble.

hth

cheers