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Chain ring


webby's picture

By webby - Posted on 07 July 2015

I need to replace my chain and cassette and jockey wheels.
My bike is only 9 months old but I guess the wet conditions in Sydney won this fight.
Now at my LBS I took the bike in and they said if I replace my cassette and chain I should be replacing my Chain rings too otherwise they cant guaranty my safety as the chain will slip..
I spoke to my mate who builds bikes as a hobby and he said its BS..

Does having to replace a 9 month old Chain Ring sound right?

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Discodan's picture

There's no definitive answer but you can easily see if a chain ring is worn by the tooth shape. Feel free to post a pic of the teeth and you'll get lots of free opinions. I'd be surprised that it would need changing (or the cassette for that matter) on the first chain swap, is it steel or Al? Normally I'd go through 3-4 chains for a cassette and chainring but your mileage may vary

moggio's picture

Why do the cassette, jockey wheels and chain all need replacing? If they are that bad then your chainring would probably be just as bad.

What are the symptoms that led to the conclusion that such major rework needed to be done to the whole drivetrain after 9months?

Flynny's picture

If your cassette is worn the chainring is most likely too.

Think about it, there a 9,10 or 11 sprockets on the cassette to spread the wear.

Even if you run a triple front ring set up I'd guess you spend the majority of time in 1 of them and maybe 4 or 5 of the back sprockets.

That's 1 ring subject to the same wear as 4 or 5 sprockets

If your chain goes past the recommended stretch you have 3 options.

1.) Leave the old chain on and let every thing wear right out to the point where it's is skipping and not changing gears smooth then change the lot

2.) Change the lot now

3. ) Change bits a pieces, cassette and chain and hope your chain ring will mesh ok.. It may still work but as the teeth will be worn it will mean the chain and therefore the cassette will wear faster (There'll be different pressure/wear zones on the front ring compaired to the back cassette)

Riding in the wet on sandstone soils does accelerate wear (sand particals cling to every thing and make it like cutting paste or sand paper).

If you keep an eye on chain stretch (You can buy prefab gauges or just measure out from the centre of on link pin and the 12" mark should be with in 1/8" from the center of another link pin.) you should get atleast 3 or 4 chains out of a cassette and chain ring

PS when I worked in a shop the term "a mate who builds bikes for a hobby" was always met with a slight cringe. 5% of the time said mate build cool retro stuff from scratch, which is good. 5% they were a pretty swicthed on home mechanic, which is good. 90% of the time said mate was a self proclaimed expert who did thing like fill up suspension forks with water "Hydraulic! Well der Hydro means water mate..." or took a set of stilsons to q top cup trying to tighten a threadless headset...."

Moral of the story, it's sometimes wise to be suspicious of advice from well meaning mates (yes I see the irony of a stranger on the interwebs giving advice).

DudeistPriest's picture

I've got 18 months and about 7k on my large chain ring (38 tooth Truvativ), in that time I've replaced the cassette and chain (both XT) about three times and the jockey wheels once (XTR).

hawkeye's picture

As a money-saving trick, may I suggest running 3 chains in rotation on the same rings and cassette.

I've been doing this for a few years after misunderstanding a friend's advice (!) and found my cassettes rings and chains have lasted many times the life of a single unit.

the reason for this is that as a chain wears, it stretches, putting a significant wear load on both the rings and cassette. If you can spread the wear across multiple chains it dramatically extends the life of the other drivetrain components.

My routine runs like this:
* Chain 1 goes on. Gets dirty, comes off, clean Chain 2 goes on. Chain 1 gets cleaned, hung up to dry and then packed in a sealed sandwich bag.
* Chain 2 gets dirty, comes off, clean Chain 3 goes on. Chain 2 gets cleaned, hung up to dry and then packed in a sealed sandwich bag.
* Chain 3 gets dirty, comes off, clean Chain 1 goes on. Chain gets cleaned, hung up to dry and then packed in a sealed sandwich bag.

And around we go.

Chains are a helluva lot cheaper than replacing rings and cassettes all the time. Saves me a fortune - compare my spend to Dudeist's. My

Oh, get the highest spec chain you can, they wear better. I've been using KMC X10SL that have been pretty good, but have snapped a couple so will likely swap to XTR.

DudeistPriest's picture

But what is your spend?

pharmaboy's picture

For inexperienced people, I'd do what Hawkeye says - 3 or 4 chains in rotation - though to make it more realistic, I'd just swap them over every 2 months - those quick links do wear the more they are used and chains should be just wiped and cleaned on bike.

No idea on your chainring - most people change one thing at a time, and if it needs replacing, you know pretty quick - if the chain was 3/16ths stretched when replaced (over 12 inches), then yes, chances are, it's a whole drivetrain, 1/8th will be probable one item (chainring if it's a lightweight alu model)

hawkeye's picture

Over the last 2 years on the Scalpel, just the original extra chains at about $40 each.

It also means I can swap wheelsets without a too-long mismatched chain trashing the Ti cassette on the race wheels.

Flynny's picture

I do the same as Hawkeye. The trick though is regular changing, making a point to change after each wet ride no matter if chain has only been on one ride
.
1 chain on the bike. 1 chain soaking in some Pro gold lube, 1 Chain hanging up to dry. Rotate them through.

moggio's picture

What Flynny says makes great sense, but as an example, my last drivetrain I did everything wrong (I meant to do the chain swap thing), but I rode it for three years a 3-4 times a week, in wet and dry. maybe sometimes I rinsed after a muddy ride and put lube on every so often. Finally just before I was about to put on a new drivetrain, the chain snapped actually in the middle of a link!

Jockey wheels were very worn, front ring quite shark toothed and cassette a little worn in the middle. I never adjusted my derailleur over the years and it never slipped, snapped or had slightest problem shifting. What this showed me with the right parts quality is so good these days that you can be completely reckless and slack and still get great results. Still I would not recommend this and I am not trying this again!

hawkeye's picture

Yes you can do that too, and that is another way to save money.

But a word if advice: don't ever borrow your friend's spare wheel - they won't be your friend after you give it back Smiling

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