Which chain?

[MrJamie]

On my hybrid Giant Roam 2 (http://www.giant-bicycles.com/en-gb/bikes/model/roam.2/4872/39040/) the chain it comes with is a KMC Z7. On KMC website (http://www.kmcchain.eu/?en/products/multiple_speed/7_speed_derailleur/) this is listed as a upto 7 speed chain, but the Roam has an 8 speed cassette. On Chain Reaction Cycles the chain is listed as upto 8 speed(http://www.chainreactioncycles.com/Models.aspx?ModelID=51830).

Firstly im confused as to why Giant and CRC use/list it as an 8 speed chain contrary to KMC?

Secondly if i were going to replace for the same level of chain should i be buying the Z8 or the Z7 ideally?

Thirdly would i see any benefit in buying one of the X8 type chains for about £18 instead of £7?

I should add that me and my bike are both rather overweight so probably put a fair strain on the chain on hills etc.

 

[Rickshaw Phil]

Chains between 5 and 8 speed are all interchangeable so there is no problem using a chain listed as 7 speed on a 5, 6, 7 or 8 speed drivetrain.

The more expensive chains may last longer and will likely be plated to reduce the possibility of corrosion. Chains are a consumable item so really it is up to you how much you want to spend.

 

[fossyant]

A new chain might need a new freewheel or cassette depending on age.

 

[MrJamie]

Thanks for replies

The bikes 18 months old and done about 2300 miles on original chain/cassette. It stills shifts smoothly and theres no sticking links, but its stretched enough that you can pull the chain clear of the teeth on the 48 crank. Will it just break at some point if i leave it?

A new chain might need a new freewheel or cassette depending on age.

Is it just a case of the sprocket teeth being worn and not meshing nicely with the new chain?

 

[Rickshaw Phil]

Thanks for replies

The bikes 18 months old and done about 2300 miles on original chain/cassette. It stills shifts smoothly and theres no sticking links, but its stretched enough that you can pull the chain clear of the teeth on the 48 crank. Will it just break at some point if i leave it?


Is it just a case of the sprocket teeth being worn and not meshing nicely with the new chain?

It may break but it's more likely if you leave it that it'll wear to the point where a new chain won't work with the original cassette and chainset. (It'll just slip all the time when you put pressure on.) Then you'll have to replace the lot.

Changing the chain before it's too worn will extend the life of the cassette and the chainrings. All being well, at 2300 miles you'll have caught it in time.

 

[MrJamie]

Changing the chain before it's too worn will extend the life of the cassette and the chainrings. All being well, at 2300 miles you'll have caught it in time.

Can you tell from a photo if the cassette looks okay? (other than being quite filthy after my last ride).

 

[compo]

I bought my new bike a couple of months ago and after 600 miles my chain is indicating .75 on the wear gauge. I have an 8 speed setup.

I remember years ago when chains/sprockets lasted years if looked after. I do not believe that with the advances in technology and materials sciences chains and sprockets should wear out so quickly, unless of course it suits the manufacturers.

 

[slowmotion]

If you don't have one already, it's worth getting a chain wear indicator, like this for example...

http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=10219

 

[Rickshaw Phil]

Can you tell from a photo if the cassette looks okay? (other than being quite filthy after my last ride).

Looking at that photo it appears to me that your 5th gear has the most wear but there is nothing obvious in the picture to say the cassette is past it. If that was my bike I'd be happy to put the new chain on and see how it went.

If it turns out that the cassette has worn out it will slip under load in the most worn gear.

Sorry if it sounds like I'm hedging my bets but as I'm judging from a photo I think that is the most reasonable answer I can give you.

 

[MrJamie]

Looking at that photo it appears to me that your 5th gear has the most wear but there is nothing obvious in the picture to say the cassette is past it. If that was my bike I'd be happy to put the new chain on and see how it went.

If it turns out that the cassette has worn out it will slip under load in the most worn gear.

Sorry if it sounds like I'm hedging my bets but as I'm judging from a photo I think that is the most reasonable answer I can give you.

I also thought it didnt look bad compared to my old MTB sprockets which had worn the teeth into weird asymetric spikes. Its only £7 for the chain and about £13 for the cassette if i need it, ill probably replace like with like and save upgrades for my next bike. I usually ride in 4/5/6 at the back so im more than happy to trust your judgement (as the alternative is mine)

I was a bit worried that I might be putting too much strain from grinding and trying to sprint my weight up short hills, being over 6ft about 18.5 stone and having strong legs from running and cycling regularly. I figure the fit guys must still put more power through, unless they just spin more so less power transfered through each chain link? Going up a short steep hill the rear axle on my raleigh mtb sheered under the cassette, so ive been a bit paranoid of extra wear and tear.

Thanks for all the replies, ill probably get a chain tool next time as im sure this ones over stretched already.

 

[MrJamie]

If it turns out that the cassette has worn out it will slip under load in the most worn gear.

So, i upgraded the chain for the nice KMC X8.99 i found reduced on wiggle, easily fitted it and it shifts amazingly smoothly and runs silently. Unfortunately my cassette is so far past gone - it slips very easily in the 3 most used sprockets even under light pressure. For now ive put the old chain back on with a powerlink, so the bike works and to not wear the new chain.

Replacing the cassette looks pretty easy, can i put on pretty much any shimano 8 speed cassette? It came with a HG40 11-32, so this cheapy HG41 11-32 for £10 would simply replace it? http://www.chainreactioncycles.com/...le&utm_medium=Shopping&utm_name=UnitedKingdom

 

[Rickshaw Phil]

Ah, shame it's too far gone. It's not always obvious how much wear is too much.

That cassette should be fine. Any matching Shimano or Shimano compatible cassette will do the job. If you haven't already got them you'll need the appropriate tools to undo the cassette lockring and to hold the cassette still while you do it.

 

[MrJamie]

After posting the photos, i read Sheldon Brown saying about measuring the chain over 12 inches, 1/16th over was okay, 1/8th over meant new cassette and mine was 3/16ths over, so i was kind of expecting it. Makes me wonder how many miles i would have safely got out of the chain, it might be better economy in future just to run a chain and cassette into the ground and replace both each time.

Ill order the cassette and lock ring remover and probably hold the old cassette still with a pipe wrench since i dont think i need a whip for fitting the new one anyway No rush now anyway, the old cassette/chain combo still works. Im quite enjoying learning how to fix/replace things though, so really appreciate the advice on here Incredibly cheap too, £23 for new chain and cassette. Thanks for help

 

[andrew_s]

Any Shimano 8-speed cassette will be fine. Sram cassettes are also compatible, and there are also a number of other brands such as BBB. Just avoid anything that mentions Camaognolo. In general, more expensive cassettes are lighter and shinier, and may possibly last a bit longer.

To tell how worn a chain is, take a ruler and measure it.
The pins on a new chain are exactly half an inch apart. Put the chain under light tension, line up the 0 inch mark with a pin, and check the pin that should be under the 12" mark (use the 11.5" mark if the ruler is only marked to 12"). With a new chain it will be on the 12" mark, but on a worn chain it will be a little further on. At 12 1/8", the chain is worn enough that a new chain will probably slip on the cassette. If it's between 12" and 12 1/16", the cassette is effectively un-worn. In between, a new chain runs OK, but the cassette is worn enough that a new chain will wear a little faster.
There are chain checker tools that are meant to replace a ruler, but the only one that gives a good answer is the (expensive) Shimano version. The others will indicate more wear than actual, even up to the point of showing a new chain as in need of replacement.

You can carry on using a worn chain with the same cassette for quite a long time (I've had up to 7000 miles). It will be unlikely to break, but as it wears it rides higher up on the sprocket teeth and will eventually ride high enough to slip. By this time your chainrings may well need replacing for a new chain as well as the cassette.

 

[MrJamie]

Thanks for the reply Andrew, ill be putting the new chain and cassette on when it arrives midweek and probably wont get to ride much until then anyway.

Another question if anyones still reading, Ive read the factory grease is good, but should i try to wipe it off the exterior of the chain as its already attracting filth from a 7 mile very slow ride with family.