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It is well documented that Tiagra 4700 is not compatible with other 10 speed parts, and uses a different set of ratios. But what are those ratios?

  • What is the cable pull of a Tiagra 4700 10 speed shifter (ST-4700-R)?
  • What is the actuation ratio of a Tiagra 4700 rear derailleur (RD-4700)?

The 4700 cassettes do appear to be compatible with other 10 speed components.

Shimano provide a compatibility chart, but that is only useful within the Shimano product line.

Here is my attempt.

Cable pull * Derailleur shift ratio = Cog pitch

  • (Supposedly) 4700 uses 11-speed cable pull, which is 2.7
  • The cog pitch for Shimano 10 speed cassettes is 3.95
  • So 2.7 * Derailleur shift ratio = 3.95
  • And we get 1.46296
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  • 1
    You have assumed that the cable pull is the same between Shimano 11 speed and 4700 but actuation ratio is different. I would have thought that derailleur geometry is the same therefore actuation ratio is the same but cable pull differs. That's how it works with everything that uses the classic 1:1.7 actuation ratio.
    – Argenti Apparatus
    May 24, 2020 at 11:53
  • Just curious, why do you want to know?
    – Argenti Apparatus
    May 24, 2020 at 11:56
  • I don’t think 4700 uses the classic ratio, which is where the incompatibility lies
    – sdgfsdh
    May 24, 2020 at 12:12
  • 3
    4700 (and GRX 10 speed) definitely does not use 1:1.7. What I mean is you have assumed cable pull lengths are the same and actuation ratios differ. I disagree, I think 4700 and 11 speed derailleurs have a common actuation ratio (1:1.4 I believe) but the 10 and 11 speed shifters pull slightly different lengths of cable. The test would be to see if a 4700 derailleur works with an 11 speed cassette and say a 105 R7000 shifter.
    – Argenti Apparatus
    May 24, 2020 at 12:37
  • 2
    Fwiw I've used 11-speed Shimano road RDs along with ST-4700 and can confirm they work perfectly.
    – Nathan Knutson
    May 29, 2020 at 17:44

3 Answers 3

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According to this YouTube video, you can combine:

  • Shimano Tiagra 4700 shifters
  • Shimano GRX 812 11 speed rear derailleur
  • 11-34t 10 speed cassette

This implies that a Tiagra 4700 rear derailleur has the same actuation ratio as Shimano 11 speed road rear derailleurs, as suggested by Argenti Apparatus. This is a ratio of 1.4. 3

Plugging these numbers into the equation we get: 

Cable pull * Derailleur shift ratio = Cog pitch
Cable pull * 1.4 = 3.95
Cable pull = 3.95 / 1.4
Cable pull ≈ 2.82

So, to answer the question:

  • Tiagra 4700 10 speed shifters have a cable pull of 2.82
  • Tiagra 4700 rear derailleurs have an actuation ratio of 1.4
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Tiagra 10 speed shifters have the 11 speed pull rate. They work with any 11 speed mech - the 4700 rear mech shares the 11 speed geometry.

The Tiagra RD4700 is an 11 speed design and the shifters are "downgraded" to match a 10 speed block.

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Tiagra 4700 is NOT the same as 11 speed shifters. 4700 pulls 2.8 and consequently moves an 11speed rear mech (or 4700) slightly more than an 11sp shifter because it is to suit 10 speed cassettes. It is also happily the same as shimano standard 8 speed shifters so Tiagra shifters make a nice upgrade to a classic 8 speed drivetrain , but with 2 spare clicks. The left shifter I found was fiddly to get to shift the 8 speed front mech just right, but possible.

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