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
  • 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 at 11:53
  • Just curious, why do you want to know? – Argenti Apparatus May 24 at 11:56
  • I don’t think 4700 uses the classic ratio, which is where the incompatibility lies – sdgfsdh May 24 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 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 at 17:44

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
| improve this answer | |

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.

| improve this answer | |

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