I've bought the Shimano HG40 chain which is advertised as a 5,6,7 and I think 8 speed chain. I've just received it and it also says 15,18,21,24. (Obviously including the front gears). My bike is a 2x6 so it's got 12 gears, why isn't that listed and will it still work? Surely it has to since it seems to be one of the only chains for 6 speed. Thanks, Harvey.

1 Answer 1


It will work adequately on your 6 speed rear cluster. Its basically 8 speed chain which is identical width to 7 speed chain, and its "good enough" for 6 speed.

Curiously, on a supplier's website for HG40 I notice this line:

Shimano Altus HG40 6-7-8 Speed Chain
7.3mm chain width, optimised for 7- and 8-speed HG drivetrains

6 speed is 0.5mm wider but given the tolerances of the day, that should work adequately. You have to move the derailleurs a tiny bit further to make a shift if its friction shifting. The FD cage may need to be closed up slightly.

Finding 5+6 speed chain will be interesting - even KMC's own chain checker only lists 8 speed chain as the best option. http://www.kmcchain.eu/chain-road_cross-multispeed-5_speed

Apparently "clarks CL20" is 5 and 6 speed chain and may be found at various on-line suppliers.

6 speed is a comparatively old standard and is way less common now, so not worth printing on the packaging?

As per https://en.wikipedia.org/wiki/Bicycle_chain#Width

6 speed – 7.8 mm (5⁄16 in) (all brands)
7 speed – 7.3 mm (9⁄32 in) (Shimano HG), 7.1 mm (9⁄32 in) (SRAM, Shimano IG)
8 speed – 7.3 mm (9⁄32 in) (Shimano HG), 7.1 mm (9⁄32 in) (SRAM, Shimano IG)

  • 1
    Thanks very much, it's an 80s bike I'm restoring (should be working today :)) so that's why it's 6 speed, I'm doing it period correct too so no upgrade, it's got downtube shifters too so I don't need to worry about the indexing being off. Cheers. Jun 9, 2018 at 9:35
  • I've used 7 speed clark chain and its suspiciously cheap. But it hasn't failed on me yet, and comes with a chromed quicklink compared to the dull grey chain.
    – Criggie
    Jun 9, 2018 at 20:35
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    As you're using "5/6" in your answer, can I assume that chain width wise the 5- and 6-speed chains are identical? Also, regarding the last list: the wiki seems to be updated and the 7.8 mm width for 6-speeds is no longer mentioned. Not sure if the wiki is correct, therefore not editing this myself. Feb 12 at 12:54

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