Confused about chains!

[BigTone0777]

Hi Guy's, I've read about chain widths before but now the more I think about this problem I have the more I'm confused!

I got a little 24" wheeld mountain bike given for my son which had 6 speed grip shifts on that he couldn't get along with. I fitted a 7 speed block and some 7 speed rapid fires I had kicking about but it seems that the chain is rubbing the block in the higher gears causing it to jump however I thought 6 and 7 speed chains were the same width. Is this right or is it that a 7 speed chain is compatible with a 6 speed block and not the other way around?

 

[HLaB]

Not that it helps but I thought 6-8 sp chains were all the same too, only 9, 10 & 11 varied but there was a thread the other day about a SRAM 8sp link not fitting a 7 sp chain

 

[BigTone0777]

Not that it helps but I thought 6-8 sp chains were all the same too, only 9, 10 & 11 varied but there was a thread the other day about a SRAM 8sp link not fitting a 7 sp chain

That's exactly what I thought!

 

[Alembicbassman]

you can use the 6 speed cogs with a 7 speed shifter, may be worth putting it back on.

If not try adjusting the Hi Lo limits on the rear derailleur.

I swapped a 5 speed for a 6 speed on a recent conversion without issue, but the rear derailleur needed setting up properly.

 

[BigTone0777]

you can use the 6 speed cogs with a 7 speed shifter, may be worth putting it back on.

I tried that before I changed the block but couldn't get it to index properly. Maybe it's another problem such as the shifter or the mech. I'll investigate further as I've got spare mech's too

 

[RecordAceFromNew]

Irrespective of what it says on the tin 5, 6, 7, 8 speed chains are generally 7.1mm or 7.2mm wide and are interchangeable - the reason being that the rear sprocket pitch of 5-8 speed are all between 4.8mm and 5.5mm and cassette/freehweel sprockets are no more than 2mm thick. Single speed chains on the other hand are ~7.8mm or wider and are incompatible. 9 and 10 speed chains still work on lower speed drives, they just wear quicker.

All derailleur chains are narrow enough to slip between chain rings, so imho not much point in choosing chain based on whether they would. I run a 9 speed chain on a 80's (presumably 5 speed) chainset without any issue.

 

[Zoiders]

The difference you have to watch out for with 5/6 over 7/8 is the lack of profiling to aid shifting on some 5/6 speed chains.

They will run but it will be clunky.

 

[BigTone0777]

Changed the chain and the mech as it looked a little twisted for part's I had lying around and it's working a treat now. Thanks for all your advice!

 

[albion]

It's weird how we often read a 'wiki here wiki there' and then come up with a different version of what is stated. Historians probably had it much easier in that past in that they mainly all made exactly the same regional observations.

 

[RecordAceFromNew]

It's weird how we often read a 'wiki here wiki there' and then come up with a different version of what is stated. Historians probably had it much easier in that past in that they mainly all made exactly the same regional observations.

Imho part of the reason for the phenomenon is profit for nothing - you'd often find them charging more for an "8 speed" chain than a "7 speed" chain, and a "7 speed" chain more than...

 

[albion]

Well I read somewhere that 6 and 7 are generally 7.3 or 7.4 pin width whilst a 5 speed is/was 7.8mm.10 speed goes down to maybe as little as 6.3mm.Even though they are all 3/32" plate to plate width.I'm sure if it says on the tin 7.4mm width it will be 7.4mm.