Using a narrower chain

[Mark_Robson]

Quick question, Would there be an issue with using a 10 speed chain on 8 speed running gear?
The running gear is a mix of Shimano 105 and Tiagra. The cassette and chainrings look to be the same thickness but I'm not sure about the rear mech. Also would the narrower chain reduce rubbing on the front mech?

 

[fido]

I asked the very same question at my LBS the other day. I'm not sure I fully understood the answer but the upshot was that it won't work properly.

 

[Tynan]

don't the widths of everything get narrower as the number of gears increase?

otherwise we'd all have thirty speeds init?

 

[Big John]

I've picked the following up from the net...........

It is possible to cram sprockets closer together only by slimming down the chain. This has been accomplished mainly by reducing the amount by which the rivet pins protrude from the link plates, thus 8-speed chain also works fine on 7-speed, 6-speed and 5-speed systems. With the development of 9 and now 10-speed cassettes it was necessary also to reduce tooth thickness, so 9 and 10-speed chains are incompatible with other systems. Exceptions to this rule are that Shimano 9-speed rear mechs will also accept 8-speed chain – so they can be used on any system with fewer rear sprockets – and that Campag "C9" chain will also run on Campag 8-speed sprockets, allowing a Campag 9-speed rear mech to be used.

 

[Mark_Robson]

Thanks for the reply guys, Oh well it was just a thought

 

[RecordAceFromNew]

Firstly I have to declare I have never tried what was asked, but I have read the quote from CTC referred to by Big John above but it doesn't seem logical to me especially where it suddenly refers to rear mechs. I am more inclined to trust Sheldon Brown (http://www.sheldonbrown.com/speeds.html), who said:

"Chain. As you go to more sprockets on the cassette, you need a narrower chain. However, using a narrower chain with an older system rarely presents any problem. Thus, you can use a "9-speed" chain with a 7-speed or 8-speed system, or a "10-speed" chain with a 9-speed system. Since the chains designated for more gears are usually more expensive and don't last as long, this is not the ideal approach, but it's perfectly workable."

The reason why Sheldon is likely to be right is because there is very little difference between the sprocket thickness of 7/8/9 speed (1.75mm to 1.9mm) and 10 speed (1.6mm to 1.7mm), depending on brands etc., and similarly for such chains' inner plate width (which are typically between 2.15mm to 2.45mm). The big difference for the chains is in the thickness of the chains' plates and pins' width. Typical width of 7/8 speed chains are 7.1mm, 9 speed chains are 6.8mm, but 10 speed chains are much narrower at around 6.2mm.

Bearing in mind that the great man never said you can use a 10 speed chain on a 8 speed system, from the dimensions I suspect it will probably work but it may be tricky to get it indexed nicely. There is also more risks for the narrow chain to fall between the chain rings.

If anybody has tried, please do post their experience.

 

[Steve Austin]

Why would you want to use a 10 speed chain on an 8 speed system? You can buy 8 speed for less then 10 speed so its money down the drain...

if a system is designed to use certai parts, it WILL work better with the parts designed for that system.

Feel free to discuss it further, but i can't really see any point in using the 'wrong' parts on a system not designed for it

 

[beancounter]

Also would the narrower chain reduce rubbing on the front mech?

Rubbing on the front mech can usually be eliminated by setting it up correctly.

bc

 

[swee'pea99]

Why would you want to use a 10 speed chain on an 8 speed system? You can buy 8 speed for less then 10 speed so its money down the drain...

+1

10 speed chains also wear out much quicker.

 

[Mark_Robson]

The reason for the enquiry is that I have a spare 10 speed chain lying around and I disagree with the comment that rubbing on the front mech can be eliminated by setting it up correctly. IMO you can not avoid rubbing on the front mech with indexed gears if you want to use the full range of gears. Saying that the amount of rub on my 20 speed bike is less than on my 16 speed bike and that got me looking at what the difference between them is, and the main difference seems to be the chain diameter.
I realise that running the chain at extreme angles is a quick way to wear out your sprockets and chain but I would like to minimise the need to trim.

 

[ASC1951]

IMO you can not avoid rubbing on the front mech with indexed gears if you want to use the full range of gears.

In that case your O is wrong. You don't have your front derailleur set up correctly, or the indexing, or both, or it's user error. Given that you mention using "the full range of gears", I would put my money on user error.

By all means try the 10 speed chain, but it may not run or change smoothly. I would have thought a tenner for the correct chain was worth it.