Replace chain only or enite drivetrain/groupset?

Rouxenator

Rouxenator

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Replace chain only or entire drivetrain/groupset?

I recently twisted the chain on my mountain bike and the guy at the bike shop that fixed it said the chain is about 75% worn. He also said that when I replace it I'll have to replace the blades (front gears), cassette (rear gears) as well as both derailleurs - so pretty much the whole drivetrain.

Understandably this can be pretty expensive! The bike is currently fitted with a Shimano Acera/Alivio drivetrain and it costs about R1600 to replace. Considering this is an entry level 29er that only cost R5000 it makes sense that is fitted with a drivetrain built for recreational mountain biking. However I use the bike 50/50 between commute to work and long/technical trail events. The bike has done 1700km since I got it in September.

So now I have three options.
1) fit a cheapish (R300~) new chain and hope everything goes ok for another 1000km
2) fit a new drivetrain similar to the one I have (R1600~) and get another 2000km out of the bike
3) upgrade to a groupset intended for more than recreational use such as Shimano Deore (R5000) although I am not sure how much longer it will last than the cheaper options.

I could also list buying a new bike factory fitted with Deore groupset but those cost R10k+ so its not really an option for me.

My question is can you simply fit a new chain and hope to get reasonable mileage with replacing anything else?
 
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Can't help you but have you thought about converting to single speed ?
 
Is the drivetrain worn?

I would just replace the chain, if you really need to then you can replace the other stuff later on.
 
Single speed..... raaaait, that will work just perfectly especially considering I am doing the Trans Karoo in two weeks time. 240km with one gear.... mkay :p

I'm also thinking along the lines of just replacing the chain but most forums online, including some motor bike ones, recommend that you replace the gears when you replace the chain.
 
Rouxenator said:
I'm also thinking along the lines of just replacing the chain but most forums online, including some motor bike ones, recommend that you replace the gears when you replace the chain.
Click to expand...

Are they worn? Post pics of gears.
 
LBS is talking bull most likely as you have only done 1700km. Also how is he measuring chain wear? If he is using a ride/no-ride chain wear tool then find a new LBS, if he actually used a ruler then trust his advice. Also you only replaces your cassette / chain-rings when you have exceeded the chain wear limit. Even then I've done it before and there was nothing wrong with my cassette.

A cheap chain is R100-R200 so check out CWC.

You would only replace your derailleur if you mangled it.

(EDIT: Rule of MTB is 1 cassette to 3 chains, 1 chainset to bonus-time ;) )
 
Rouxenator said:
Single speed..... raaaait, that will work just perfectly especially considering I am doing the Trans Karoo in two weeks time. 240km with one gear.... mkay :p

I'm also thinking along the lines of just replacing the chain but most forums online, including some motor bike ones, recommend that you replace the gears when you replace the chain.
Click to expand...

I would also say just replace the chain except for the little fact you mentioned above ... now it boils down to what Ponder asked about the condition of the drivetrain.
 
Thanks, I checked out CWC and it seems the only 8 speed chain they have is this not too shabby looking SRAM http://www.cwcycles.co.za/product/sram-pc-951-chain which seems perfect at R160. Will try to post some pics of the gears when I get home tonight. Still need to clean the bike cause it picked up a lot of mud this weekend on the Lourensford ride.
 
Rouxenator said:
Thanks, I checked out CWC and it seems the only 8 speed chain they have is this not too shabby looking SRAM http://www.cwcycles.co.za/product/sram-pc-951-chain which seems perfect at R160. Will try to post some pics of the gears when I get home tonight. Still need to clean the bike cause it picked up a lot of mud this weekend on the Lourensford ride.
Click to expand...

That SRAM chain is nice, I got one (still in its bag) ;) ... just keep your chain clean and use proper lube
 
Rouxenator said:
I recently twisted the chain on my mountain bike and the guy at the bike shop that fixed it said the chain is about 75% worn. He also said that when I replace it I'll have to replace the blades (front gears), cassette (rear gears) as well as both derailleurs - so pretty much the whole drivetrain.

Understandably this can be pretty expensive! The bike is currently fitted with a Shimano Acera/Alivio drivetrain and it costs about R1600 to replace. Considering this is an entry level 29er that only cost R5000 it makes sense that is fitted with a drivetrain built for recreational mountain biking. However I use the bike 50/50 between commute to work and long/technical trail events. The bike has done 1700km since I got it in September.

So now I have three options.
1) fit a cheapish (R300~) new chain and hope everything goes ok for another 1000km
2) fit a new drivetrain similar to the one I have (R1600~) and get another 2000km out of the bike
3) upgrade to a groupset intended for more than recreational use such as Shimano Deore (R5000) although I am not sure how much longer it will last than the cheaper options.

I could also list buying a new bike factory fitted with Deore groupset but those cost R10k+ so its not really an option for me.

My question is can you simply fit a new chain and hope to get reasonable mileage with replacing anything else?
Click to expand...

Hmm....

I don't see why you should replace the derailleurs. They are only replaced if they are bent and not fixable.
Your chain should be replaced if they say so (it stretches, there is a "chain meter" that tells you how far it's gone, as they say 75%).
If your chain is worn and you keep riding with it, it will eat into your front blades and your rear sprockets. This will cause them to have to be replaced.
It's easy to see if your front blades need to be replaced - are they noticeably eaten? The rear blades are harder to tell, but you will be able to feel - do they slip easily and is your shifting crappy at times? (This is assuming your gears are indeed set correctly and your cables are still fine).

Btw, I had around 30'000km on my front and rear derailleurs before I finally replaced my entire groupset.
In general you should get around 2000-3000km out of a chain if you stay on the road. It's harder for me to guess with an mtb since the wear is more.

Oh, and motorbike chain.... completely different to that of a bike :p
 
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GarethC said:
May I enquire how you managed to twist your chain?
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I missed that bit.
WTF.... :D
I've never managed to bend a chain... by using it on the bike as it's intended, I fail to see how it's possible.
 
Rouxenator said:
I'm also thinking along the lines of just replacing the chain but most forums online, including some motor bike ones, recommend that you replace the gears when you replace the chain.
Click to expand...
There is no need to replace the gears even on a motorcycle, unless they are worn.
 
On a superbike, replace sprockets when replacing the chain. (Unless your sprockets are in mint condition and well looked after) But they work a whole lot harder than a bicycle. :p So you can't compare.
 
Oh the chain twist, funny thing actually. It was after the Argus MTB and I was cruising back to the bakkie to load my bike, in the parking area the chain fell off the lowest blade and got stuck between the crank and the BB. I tried pedalling to get it out but it would not budge. Eventually I managed to pull it out with lots of force.

...and that is how I bent my chain... what a chop :(
 
That's why you should get a chain guard (iirc that's what you call it) :p
 
Rouxenator said:
Aren't those only on the outside? (after top blade)
Click to expand...

You thinking of the front derailleur? No, you get a little plastic clamp that sits on your seat tube next to your small chainring.
http://www.chainthong.com/images/chain-guard.jpg <== it looks like the black cable tie thingy on the tube, but lower down. If the chain falls off the inside, it lands on that instead of between the crank and the bottom bracket.
 
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