Brompton owners - how many miles do you get out of a chain / sprockets?

[wafter]

It's good to try it though...

If you hadn't you'd always have wondered if we were just spending money for the sake of it.

I think Wafter's method of running two chains would mean you can probably get twice as many miles as long as the chains are swapped very regularly.

As I've said elsewhere recently, it's still a fairly cheap swap so to me it's not worth the additional hassle of trying to remember to swap the chain. But, as I do remove it all to clean wouldn't actually be any extra work as such.

Double the life is probably pushing it as it'll still wear regardless of chain position, but I'd expect it to extend sprocket life beyond what you'd get using a single chain.

@EltonFrog - seems your drivetrain has worn at about four times the rate of mine; which seems very rapid although IIRC Brompton advise changing chain and sprockets at 2k miles and who's to say what level of wear would be present then... so maybe your experience isn't too far from the manufacturer's expectations.

Every time I order from a Brompton supplier I toy with the idea of buying a spare set of sprokets but am always put off by the thought that the ones I have might not need replacing for years.. I think when one starts slipping I'll likely just replace that one in isolation and leave the other in place to get the most life out of it.

My gut tells me that the 13T sproket will likely last longer since it's signficantly thicker and the tooth profile maybe a bit more resileant.. interestingly the current spec sprockets now share the same "multi speed" profile of the 16T; I wonder if the deeper tooth profile on my 13T sprocket is contributing towards the damage I'm getting from the chain striking the rear frame during shifting..

 

[Kell]

Maybe double the life was phrased incorrectly.

For me, if I could make a sprocket set last two chains instead of changing it with the chain, it would double the mileage I get out of one.

The only way of doing that would be to change chains more regularly so it doesn't wear as each chain 'stretches'.

 

[T4tomo]

Maybe double the life was phrased incorrectly.

For me, if I could make a sprocket set last two chains instead of changing it with the chain, it would double the mileage I get out of one.

The only way of doing that would be to change chains more regularly so it doesn't wear as each chain 'stretches'.

doing two chains to one cassette in road bike world is a "thing" because cassettes are relatively expensive cf a chain. When a sprocket / sprocket set is cheaper / same price as a chain then running them until they skip and then changing both together is the optimum way forward.

 

[wafter]

doing two chains to one cassette in road bike world is a "thing" because cassettes are relatively expensive cf a chain. When a sprocket / sprocket set is cheaper / same price as a chain then running them until they skip and then changing both together is the optimum way forward.

Are you sure about this? It seems that running a worn chain on any sprocket will accelerate wear on the sprocket, but for your proposition to hold true doesn't that assume that running a worn sprocket with a new chain would reduce chain life; which I'm not sure is the case..?

It seems that regardless of component cost it's a good idea to run multiple chains in rotation to prolong cassette life; the only limiting factor spending so much on multiple chains that you never wear them all out and hence don't get your money's worth..

 

[wafter]

Maybe double the life was phrased incorrectly.

For me, if I could make a sprocket set last two chains instead of changing it with the chain, it would double the mileage I get out of one.

The only way of doing that would be to change chains more regularly so it doesn't wear as each chain 'stretches'.

Yeah, it's an interesting thought isn't it? The question at the end of this particular rabbit hole appearing to be how many chains you can buy and rotate before you end up dying in possession of a hundreds of pounds worth of barely-worn drivetrain components

 

[Kell]

Are you sure about this? It seems that running a worn chain on any sprocket will accelerate wear on the sprocket, but for your proposition to hold true doesn't that assume that running a worn sprocket with a new chain would reduce chain life; which I'm not sure is the case..?

It seems that regardless of component cost it's a good idea to run multiple chains in rotation to prolong cassette life; the only limiting factor spending so much on multiple chains that you never wear them all out and hence don't get your money's worth..

The problem (as I understand it) is that the cassette teeth will wear as the chain rollers do (let's call this chain stretch because most people do) because the length between links changes and creates the wear.

So most of the wear you get is not just from simple use. So if you could stop the chain from stretching, the sprockets wouldn't wear as fast. You cant' stop the chain from stretching, but using two (possibly more) and switching between them means that the sprockets won't wear as ONE chain does and it spreads the excess wear across more than one chain.

And it's the excess wear that means they're not compatible with a new chain.

I've never really understood why the chainring doesn't wear at the same rate - especially as that's locked to your pedal stroke. But it's definitely possible to make a chainring/set last for multiple chains and cassettes.

 

[wafter]

The problem (as I understand it) is that the cassette teeth will wear as the chain rollers do (let's call this chain stretch because most people do) because the length between links changes and creates the wear.

So most of the wear you get is not just from simple use. So if you could stop the chain from stretching, the sprockets wouldn't wear as fast. You cant' stop the chain from stretching, but using two (possibly more) and switching between them means that the sprockets won't wear as ONE chain does and it spreads the excess wear across more than one chain.

And it's the excess wear that means they're not compatible with a new chain.

I've never really understood why the chainring doesn't wear at the same rate - especially as that's locked to your pedal stroke. But it's definitely possible to make a chainring/set last for multiple chains and cassettes.

Yes; I'd agree with that broad-strokes. If you had a magic chain that never elongated (let's not perpetuate the nasty "stretch" misnomer!) the sprockets would still wear but at a much lower rate.

As you allude to the elongation in the chain increases wear as it pushes the contact point forward and up the teeth, meaning engagement happens progressively less tangentially to the direction of travel at the sprocket's circumference and closer to the point where the chain will slip.

Not sure about the chainrings - obviously they have a lot more teeth than a typical single sprocket; might also be something to do with their larger diameter spreading the load over multiple chain links compared to the smaller sprockets..?