Chain longevity: swapping chains or keeping same for longer?

[Titiritero]

Slowly building a retrobike for a long touring trip starting in about a year. I'm still debating if staying with 7/8 speed or going to 9 (only because I can find a 36t cassette).

Nevertheless, I read often that the best to keep the components running for longer is to go with 2 chains and swap them every 2000km or so. What is the logic behind that? What is the benefit of installing a 2k old chain again? Why not run one until it wears (but before it wears the cassette) and then install a new one, and so on?

What am I missing? I plan a 24k trip, so the longer the components last, the better.

 

[2manyoranges]

The more a chain stretches, the more the cogs wear - the stretched chain is a major cause of wear on rings front and rear. The ‘2 chains’ theory is that by switching you keep with an unstretched and then less-stretched chain for longer. Simples.

 

[mattr]

Yup, the "less stretched" chain will still mesh with the cassette and chainrings. As there is only 2000km extra on it.
In theory you might be able to double the life of the chainrings and cassette. In practice, you might add ~75%.

And whether you stick 7/8 or go 9 might be dependent on what you can get hold of where you are going, and what sort of riding are you doing?

i.e. how far between bike shops, and what sort of kit are they likely to have.....

 

[The Bear]

I'd be willing to bet that 7/8 speed chains last longer too.

I read an article on chain life a while back that claimed many top (road) cycling teams were able to keep the same chainings for a whole season with regular chain replacement. I bet they do a fair few miles too...

 

[greencat]

I'd be willing to bet that 7/8 speed chains last longer too.

I read an article on chain life a while back that claimed many top (road) cycling teams were able to keep the same chainings for a whole season with regular chain replacement. I bet they do a fair few miles too...

Yes, a roadie friend of mine used to replace his chain once a month. Not sure how often he replaced his cogs & chain rings.

I've usually had the same cogs/chainsets for 3-4 chains.

 

[mattr]

Not really applicable though, most top road teams will be spreading each riders load over 3 or 4 bikes. At least.
Plus they'll be cleaned and lubed daily.

The bike/bikes they have at home will not get their chainrings to last a season........

My record is 4 months, for chainrings. New groupset, months training in the UK, 2 weeks in spain, 2 weeks back in the UK, 10 day race, 2 weeks back in the UK, new chainrings. Also did a couple of sets of tyres, bar tape and a complete re-cable of the bike in that time.......... No idea how many chains. And thats very very much bottom end road team.

 

[2manyoranges]

Re:

Well, I think that lesser-gear-chains do (last longer). I did thousands of off road miles on my Marin steel bikes in the 90’s - the group sets lasted forever. We were lucky in that this was in the South Downs where the mud is more of a lubricant than an abrasive - one week on gritstone seems to be the equivalent of ten years on chalk. But 7-8 lasted a hell of a lot longer than 9. Regular cleaning vital, and we spent years experimenting with how to de/grit and re/lube a chain.

Brush off
Shake in diesel in a big tin or jar
Hang up to dry
Shake all the grit out by wiggling it a lot
Refit
Load with Castrol motorbike chain wax
Done

 

[mk one]

Like above, seemed to have less trouble with older style chains.

Not everyones choice but back in the day i tried just about every oil and lube trying to find one that didnt collect grit/dirt. In the end i started running my chain dry. Just used to make sure it was cleaned regularly and dried and it lasted years, never had any problems.

 

[Titiritero]

Re:

Thanks for the answers above. What I still don't understand is that, if let's say a chain will start wearing out a cassette after 4000 km... what is it going to be a difference of having 2 chains and swap each after 2000 km, instead of using one, going up to 4000 km, throw it away, then get another new one, another 4000 km, etc?

Will the swapping of the chains mean I would get more than the expected 4000 km per chain?

I see why installing a used 2000km chain would be better than the one still there after 3900 km, but this replacement will also reach that number once its second "shift" is about to end...

(please remember numbers given are illustrative, not factual)

 

[Woz]

Re:

Keep it simple. No faffing about, spend £5 on a proper chain wear indicator that will determine the state of it properly.

When it gets to 0.75% wear, swap it out for a new.

Keep the old for a spare (or pass me down for the pub bike).

You then won't need to worry about cassettes and rings too much. After about three chain swaps I usually ditch the cassette, or at least close inspection comparing to a new cassette since tooth profils are misleading. Usually it would only be a couple of sprockets worn. Chain rings get ditched much later.

Hell, if you got steel chain rings they would practically last forever with a timely chain swap out.


The price of a chain and cassette at Deore/Tiagra/105 level is very reasonable.

Counting km's for a chain
is a utter joke to begin with as there are so many variables.