Transmission life

For discussions about bikes and equipment.
fatboy
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Postby fatboy » 25 Jun 2008, 10:15am

It's not all bad wearing out your cassette, means you get to change set-up. In my case I changed my cassette only to discover that my biggest cog was 30 not 32 that I had assumed. So I've now gained a lower gear or two.

I actually landed up with an SRAM cassette which has different ratios to Shimano. They seem to work well for me.
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly

ciuffolotto

Postby ciuffolotto » 27 Jun 2008, 1:06pm

I commute mostly off road and the sandy mud demolishes chains and cassettes - I reckon on 2 months per 9 speed chain in winter, so around 1500-2000 miles. 9 speed cassettes maybe 4000 miles, more if I'm disciplined with the chain checker and changing chains. I've gone back to the Rohloff which gives a year per chain and one side of the rear sprocket in the same regime!
I'm on the bike day in, day out, often very early or late, and the bike gets a chain clean once a week at most.
Mountain biking is much worse. I've written off a chain in a couple of weeks in a Welsh winter!

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lauriematt
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Location: shropshire

Postby lauriematt » 27 Jun 2008, 5:52pm

jus cleaned my chain...take a look:
Image
just checked my old MTB chain...with park tool...measured well over 1percent!
WHAT DOESNT KILL YOU .... CAN ONLY MAKE YOU STRONGER

Lawrie9
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Location: Powys, Wales, UK

Postby Lawrie9 » 27 Jun 2008, 6:58pm

As a chain is about the price of a gallon of diesel you could replace it almost monthly. But the wear will depend on the amount of stress the metal is under, rainfall, road surface, weight of rider, riding style. hills so it is not easy to give a precise figure as to how long a chain should last. As a youth I seemed to go about 10 years without replacing the chain. But in those days they were made out of good quality metal that held its edge and everything was built to last rather than be thrown away every six months.

byegad
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Postby byegad » 27 Jun 2008, 10:18pm

At the same price as a gallon of diesel that's a cheap chain! No wonder they only last five minutes!

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Mick F
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Postby Mick F » 27 Jun 2008, 10:31pm

How much does a gallon of diesel cost in your part of the world, Lawrie?

My chains cost about £20 odd.
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PW
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Postby PW » 27 Jun 2008, 10:53pm

Mine are about £14. With diesel at around £6/gallon & rising that comparison will soon be accurate! :D :lol:
If at first you don't succeed - cheat!!

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andrew_s
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Location: Gloucestershire

Postby andrew_s » 28 Jun 2008, 3:09pm

It does depend a lot on what parts you buy.

It could be a £11.50 cassette or a £130 cassette

It could be a £3 chain (about 0.5 gall of diesel) or a £40 chain

A lot is dictated by how many speeds you run. Not only is 5/6 a lot cheaper than 9/10, it lasts a lot longer too (2.5x?).

If you use an expensive cassette, it is obviously best to get the cheapest chains that fit and change them frequently.
On the other hand, if you can get a cheap cassette in the right speeds/ratios, changing chains frequently could mean you end up spending a lot more on chains than you would if you ran the chain to the death and then got a new cassette as well.

___________________________________________________________


On the 1 chainring/3 cassettes/9 chains point, it's a good idea if you can do it, but...

a) you've got to keep proper tabs on which chain has been used how many times with which cassette.

b) you can put enough wear into a chain in the course of a single cycling holiday to derail the system - ie get back home and find that the next chain in sequence slips. Then you've got to put the chain & cassette aside until the wear on a new rotation of the other 2 cassettes and 8 chains has caught up. It could all get a bit confusing.

c) it would probably be good for 50,000 miles if you kept the regime going, but are you going to ride that long before getting the next new bike?
If not, what happens to the part-used chains and cassettes?

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andrew_s
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Postby andrew_s » 28 Jun 2008, 3:35pm

pigman wrote:how does one determine the length of chainlife? Is it (1) the stretch aspect, (2) the wear on the inner link plates or (3) the floppiness of the joints?

some seem to be concerned with (1) and go on to say that regular cleaning improves chainlife. How? - stretch has nothing to do with cleaning, it depends on mileage, terrain (hills/flat) , pedalling style (heaving/twiddling).

However (2) and (3) are affected by cleaning, but have a lot do with variation in chainline (tough terrain means more gears used and 11 speedwill be more extreme than 5). In short, its impossible to simply quote mileage and to say cleaning is the panacea for a longer-lasting chain.


Chains don't stretch at all.
What people mean when they talk about stretch is wear on the pins and inner link plates. As they wear, you get a little bit of play at each joint, and it's the accumulated play across a number of links than makes the chain longer and is referred to as stretch.

If the joint between the pin and the inner link plate is mucky and unlubricated, it wears a lot faster than if it is clean and lubricated, and hence the chain doesn't last as long.
It's this stretch that limits chain life. The teeth on the chainring and cassette are a fixed half inch apart, and if the chain pitch gets enough larger than half an inch, you get chain slip.

The mechanics of getting the muck out from the pin/inner link joint, and the lubrication in, is another matter entirely