XT rear derailleur id / year / speed?

[sefton1275gt]

I have 3 XT derailleurs on 3 different bikes.

2 look the same. one runs a 7spd and the other 8spd

And the 3rd (which looks older) runs a 7spd

Are they fixed or could the 7spd one's also run and 8spd block? (Thinking of going 8spd)

Also, how much (roughly) are they worth?

Thanks

 

[winjohn]

The first 2 are XT 737 and the last is a 735 The 737 are 8 speed nominally, the 735 7 speed, but they are capable of 8 or 9 speed. The serial numbers are on the back of them. About 20 to 30 quid each actually the 737s look like long cages so are more sought after.

Most Shimano kit has a serial number somewhere

This is a great resource.
https://en.wikipedia.org/wiki/Shimano

 

[sefton1275gt]

So is the 739 the newest?

 

[winjohn]

Sorry I have corrected the typo that I'd originally written, the single one is the older 735. I have three or four of them in a box in my garage. I like the look of them but they have a small range.

 

[sefton1275gt]

So would they all run 8 SPD cassette?

 

[winjohn]

They would have no issue with the 8 speeds just be aware of the largest cog size and capacity. On my 735 it is given as 28 and 28.

How to calculate tooth capacity​

• (largest cog - smallest cog) ＋ (largest chainring - smallest chainring) = required capacity

For a modern, double-chainring road bike drivetrain, we would have something like:

• (32 - 11) ＋ (52 - 36) = 37t capacity

For the sake of example, let’s assume you're looking at a Shimano 11-speed road derailleur here.

The total capacity of an SS (short cage) Shimano derailleur is 35t, and 39t for a GS (medium cage) derailleur. As such, in this circumstance, you would require a medium-cage derailleur.
It bears mentioning that the quoted capacity of derailleurs tends to be pretty conservative. In practical terms, you could almost certainly get away with using a short-length cage derailleur in this circumstance, so long as you avoided extreme (e.g. big and big) gear combinations. Shimano, however, wouldn’t condone this.