Tips on how to tell if shifters are broken?

[Psyclist]

Buying a pair of Dura Ace 7900 mechanical shifters this weekend from a private seller. Just wondering how I can tell if they're broken? £150 posted sounds to good to be true. I'm covered if they're broken as I'm paying by PP Goods which gives me 45 days to claim.

So, any tips on how to check they work, without being connected to the front and mechs? (I don't have a bike to fit them to)

TIA.

Alex.

 

[HovR]

You could always thread a bit of cable through the shifter mechanism, get someone to pull gently on it to tension it, and then operate the shifter to see if the cable moves as it should.

 

[Psyclist]

You could always thread a bit of cable through the shifter mechanism, get someone to pull gently on it to tension it, and then operate the shifter to see if the cable moves as it should.

Okay, thanks HovR, I was thinking that but wasn't sure.

 

[Svendo]

One issue to look for is that with some earlier 7900 shifters the last double click down from 3rd to 1st (3rd largest to largest cog, nearest spokes) doesn't work. It does a double click, and may move onto the largest cog, but slips back down to the second. Single clicking from 3 to 2 to 1st gear works fine.
Mine have this problem. TBH I'm not sure they ever did it, and in reality I rarely notice it, and it doesn't bother me, just do single clicks when its getting really steep, which is better technique anyway. Not sure how you'd test for it without them attached to a bike, but could be worth asking.
And for £150 I'd put up with it!
Also check all the grub screws holding the 'metal' plastic bits are there at the top of the levers, one fell out of mine somehow. Managed to file down a computer screw to fit.

 

[accountantpete]

Shimano shifters work on a spring/ratchet principle both ways - so just click away both ways for a basic test.

Otherwise you can feed a bit of spare gear cable through and tie the end to a spare drive side crank (for eg) and with that suspended click away.

 

[Psyclist]

Thanks for the tips.