Thorn Cycles Forum
Technical => Transmission => Topic started by: jul on July 14, 2026, 12:34:34 PM
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Hi,
Do you think it is useful to change the chain without sprockets ?
If yes, you change it every how many miles ?
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Hi
It largely depends on your gear system. Changing chains early saves the sprockets and chainwheels and on derailleur gear systems it is usually worth it….but change by measuring chain elongation rather than miles.
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Do you think it is useful to change the chain without sprockets ?
It depends on your transmission and materials from which it is built.
I don't want to go into when I used derailleur systems, let's just say I was continually p*ss*d off at the waste and inconvenience. But those transmissions accustomed me to not expecting more than a thousand miles from an entire transmission system. I replaced the sprocket set with all the other gearwheels because they all got wrecked at the same rate as the chain.
When I went over to hub gears, I used the beautiful but soft alloy Nexus crank, sprocket and Shimano chains, and they wore out together at such a rate they never managed much better than a thousand miles.
This couldn't be right. Most of the cyclists I knew were unsmiling idiots, who believed all the nonsense on television from the climate catastrophists, and got angry when anyone didn't instantly believe the street corner gossip they retailed as gospel bicycling lore, but a few were thoughtful people, and very helpful when I made a determined effort to educate myself about bicycles.
As a byproduct of them directing me to bicycle makers who knew what they were doing, I made a major discovery. I was unsympathetic to the mushy aesthetics of the crank Utopia-velo fitted as the default option. I wanted something more classic, and while I decided what I wanted and sourced it, I told the dealer preparing the bike for delivery to me to fit a cheap crankset and give me a credit for the expensive but ugly default crank. He fitted a forged steel crank and chainring from an Indian manufacturer I'd never heard of, Amar, and this, together with KMC Z7 chain and high-quality Rohloff sprocket, was an eye-opener.
I was now in position where I got three to four times the mileage on a single chain than I had before. I want to stress that all of these transmissions operated inside full chain covers, first the Dutch plastic kind, several, then Utopia's own Country, then the Hebie Chainglider, and that my maintenance was state of the art, from white liquid wax every hundred miles or so to my experiments with running the chain solely on its factory lube inside a Chainglider for its entire life.
When I finally found cranks I liked, I discovered that the high-quality Thorn chainring I'd decided on was too wide for the Chainglider, and substituted a Surly stainless steel chainring. I now run X8 KMC chains, arguing that if the fixie Z7 was good, the derailleur X8 with its extra flex would give me an extra edge. (I have no idea whether it has worked; I don't keep the sort of detailed records Dan and Martin delight in. But the X8 is available everywhere and often on sale, and usually cheaper than the slower-selling Z7.)
Then I fitted a Bafang centre motor, which requires a dished chainring, and bought a selection of their available tooth counts that also match the Chainglider's availability for the Rohloff -- and rediscovered the virtues of steel.
I last inspected the sprocket on the Rohloff at around 11K kilometers, and there was no wear. The Amar steel chainring was on the bike for about 3000km, and while it could have done with a wire brush on the back and some Rustoleum, the blacking on the teeth wasn't even disturbed. I'm sure no one will be surprised to hear the Surly stainless steel chainring wasn't marked in the few thousand kilometers it was on the bike. The current Bafang dished chainring isn't showing any wear in about 4.5K km.
The common element is steel chainrings and a high quality Rohloff sprocket. I have throughout taken the view that the chain is the cheapest replaceable service component on the bike, and thrown off the chains at around 0.5 percent wear, in part because I wanted to start experiments with a new chain.
So my answer, based on experience, is, yes, on your Rohloff bike with the Rohloff sprocket, you can change the chain without changing the sprocket.
About your second question, after how many miles should you change the chain, that's going to be different for each of us.
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I also think that there is a case to be made, especially with the Rohloff sprocket, to ride the lot until the sprocket (or more likely the chainring, if it is aluminium alloy) starts skipping, that is, let them all wear together because that way they will fit together until they don't, at which point you flip the sprocket and the chainring and fit a new chain.
However, it may also be that with such extremely worn components, the outcome may be perverse in that it will lead to one component with some wear still left on it but being too worn to accept a new chain. That outcome can perhaps be postponed by running several chains in parallel, say for a thousand miles each, so that there is always only a small difference in wear between the chain and the sprocket, ditto for the chain and the chainring. Considering the amount of work involved, at this point I lose interest; I'm happy with my near-zero maintenance bike and consider chains a near-irrelevant expense; I'd probably have a different outlook if I were a major tourer. It would make a worthwhile experiment for someone with enough years left to let the components do their own thing to the end.
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However, it may also be that with such extremely worn components, the outcome may be perverse in that it will lead to one component with some wear still left on it but being too worn to accept a new chain. That outcome can perhaps be postponed by running several chains in parallel, say for a thousand miles each, so that there is always only a small difference in wear between the chain and the sprocket, ditto for the chain and the chainring. Considering the amount of work involved, at this point I lose interest; I'm happy with my near-zero maintenance bike and consider chains a near-irrelevant expense; I'd probably have a different outlook if I were a major tourer. It would make a worthwhile experiment for someone with enough years left to let the components do their own thing to the end.
I found running several chains in parallel was well worthwhile with derailleur systems and with unprotected hub gear systems. On large-wheel derailleur bikes with triple chainrings I used to run up to 4 chains in parallel, swapping every 300 to 500 kms on average, though this was very variable depending on weather and the type of roads (or not roads) where I was riding. So getting up to 4 times the chain life for the cassette sprockets and smallest chainring, scrapping the chains at about 1% elongation. The 2 larger chainrings generally lasted for at least two cassettes.
On hub geared bikes without chain covers, chains lasted longer, maintenance intervals were further apart, sprockets (except the Rohloff ones) are very cheap and can usually be flipped for double the use.
I still run 2 chains in parallel on bikes with ChainGliders. But the intervals between chain swaps are nearly always much longer, on one of my utility bikes bike I am currently at over 4000 kms without yet needing to remove the chain for a swap and thorough clean.
At the other end of the scale I have one Brompton with derailleur gears, this is the only derailleur bike I still have, though I do maintain some others for a nature reserve. The reason on this Brompton is that a derailleur system is lighter, the 500g or so saved compared to a Sturmey-Archer hub gear makes a difference when I have to carry the bike a significant distance. This Brompton is used in all weathers for short utility rides when I know I will be carrying the folded bike and using other transport for part of the trip. Worst case for a chain swap was a ridiculous 50 kms after 3 short trips during particularly wet winter weather. On a small wheel bike the chain is much closer to the ground and picks up much more muck from the road.
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Thanks for all that detail, Martin. I look forward to hearing that you won a multiple of five times the chain wear as a reward for your work.
The good news for Jul the OP is that he has an exciting and profitable journey ahead of him.
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I'm not sure to understand Martin ;)
So it's not possible to have a simple answer..
Usually, during my trip with my Nomad, i replace my chain every 5000 kms approxymately, to be honest at thiat moment the chain is always dead.
I return my Rohloff sprocket around 10000 kms.
And, i've never replaced my Surly chaingring (30.000kms)
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Hello,
On my Thorn Raven Twin, I replace my chain about every 7500kms and have just recently replaced the chainrings and sprocket for the first time after accumulating about 44000kms.
Regards
Hugo
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Hello,
On my Thorn Raven Twin, I replace my chain about every 7500kms and have just recently replaced the chainrings and sprocket for the first time after accumulating about 44000kms.
Regards
Hugo
44000 kms with a Rohloff Sprocket ! Are you sure ? it’s a lot of kilometers
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Hello,
On my Thorn Raven Twin, I replace my chain about every 7500kms and have just recently replaced the chainrings and sprocket for the first time after accumulating about 44000kms.
Regards
Hugo
44000 kms with a Rohloff Sprocket ! Are you sure ? it’s a lot of kilometers
If you change the chain often enough, you can make a sprocket and chain ring last almost indefinitely. The question is if it makes economic sense, as in - are you spending more on chains than you would replacing the other components? There is some disagreement on the answer to that, it depends... IMO it makes little cost difference, but letting it all wear out requires less maintenance.
I swapped (Or flipped) the lot on my Mercury at around 27,000km, though that bike doesn't see the worst of the weather or much off-road. On the wet weather/off-road Nomad I'm still expecting 15,000+ km.
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Ok, but sometimes when your replace only the chain, an unpleasant noise appears the first hundred kilometers
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Ok, but sometimes when your replace only the chain, an unpleasant noise appears the first hundred kilometers
Then you've left it too long, the wear on the sprocket, and possibly the chainring, is beyond the tolerance of the new chain. What you're doing, that noise, is premature wear on the new chain till it matches the sprocket. the economic thing to do in that instance, is to put the old chain back on. If you're going down the route of swapping chains to preserve other components, you have to frequently measure and not go by mileage.
Riders can do what they choose, but there are two practical options, wear it all out and replace together or replace chains before anything else is worn. Doing something between those two has no advantage and will cost more in components than either.
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OK i understand but lmo i don’t want to replace chains every 1000 kms.
I change my chain when the old one is too stretched around 4000 kms
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Ok, but sometimes when your replace only the chain, an unpleasant noise appears the first hundred kilometers
How many teeth on your rear sprocket?
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Ok, but sometimes when your replace only the chain, an unpleasant noise appears the first hundred kilometers
How many teeth on your rear sprocket?
16 teeths and 36 in front (Surly stainless steel) but the noise it seems to be coming from the back..
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If you're going down the route of swapping chains to preserve other components, you have to frequently measure and not go by mileage.
Riders can do what they choose, but there are two practical options, wear it all out and replace together or replace chains before anything else is worn. Doing something between those two has no advantage and will cost more in components than either.
There's Martin's middle way of swapping chains in and out at quite short intervals when his bikes ran with open chains, which substitutes maintenance time for components costs.
He told us recently that the chain-exchange intervals are very much longer when the chain runs inside a Chainglider, which, if we're talking cost accounting, shifts part of the cost onto the Chainglider. However, as I pointed out when I tested all the Chainglider competitors and in the end could recommend only the Chainglider, after a chain cycle or three the Chainglider has paid for itself and falls out of the equation for the rest of its service life (on which nobody has yet put a number; the thing may be indestructible). So, with a Chainglider and Martin's intermediate method, the costs of transmission components falls to a distant but lower plateau. My best guess is that Martin's Method will realize ever more marginal savings.
That's not much of a guess; it's simply basic economics.
Of course, all this assumes that the cyclist actually enjoys maintenance and doesn't count the opportunity cost of his own time.
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Ok, but sometimes when your replace only the chain, an unpleasant noise appears the first hundred kilometers
How many teeth on your rear sprocket?
16 teeths and 36 in front (Surly stainless steel) but the noise it seems to be coming from the back..
As chains wear and elongate, the chain links with the inner plates do not elongate but the chain links with outer plates do elongate. More on that here:
https://www.sheldonbrown.com/chain-life.html
Most people on this forum use a sprocket with 17 teeth, an odd number, thus every sprocket revolution a tooth that had a link with inner plates on it, the next revolution will have a link with outer plates on it. That is because Thorn fits bikes with a 17 tooth sprocket when new.
Rohloff hubs when sold new come with a 16 tooth sprocket, I am also running a 16 tooth sprocket. (For touring, I use the same gearing as you, 36T chainring, 16T sprocket.) Thus as long as you do not change your chain, the chain and sprockets wear to match each other. As a chain elongates and half of the links have an increased space between rollers, some teeth wear more than others.
If you put a new chain on without changing or flipping a sprocket, the teeth that were worn in to match an old chain will take some time to wear into match the new chain.
Also, if you take a worn chain off, clean it and put it back on, if you put it on so that it no longer is on the same teeth, the teeth might not be on the same links and that could cause the chain to be off somewhat.
I cut a small notch into one sprocket tooth and one chainring tooth. Every time I put a chain on the bike, I am careful to always put a link with outer plates on the tooth with a notch. Sometimes it is hard to see the notch, it fills in with grime so I also painted a spot on the sprocket and chainring. This won't solve the issue of noise when you put a new chain on worn teeth, but it may help a little bit.
I ride several different bikes, one has a Rohloff and the others have derailleurs with seven or eight speed cassettes. Most of my miles are on the derailleur bikes. Since I am wearing out eight speed chains on the derailleur bikes and I change those chains more often than you would need to change them on a single speed or IGH hub, I now am putting chains that I wore out on a derailleur bike onto my Rohloff bike to get some more wear before I discard them. Thus, I no longer put new chains on my Rohloff sprocket or chainring.
I got home from a bike tour a week ago with my Rohloff bike. I discarded the chain where I did my tour, did not bring the chain home. It was already quite worn when I started that tour. I will be putting a chain on the Rohloff bike that already meets the definition of worn out from a derailleur bike to get some additional wear on it before I discard it.
Photo attached, several years ago I took this photo before I flipped my sprocket. The tooth on the left has a lot more wear than the tooth on the right.
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If you're going down the route of swapping chains to preserve other components, you have to frequently measure and not go by mileage.
Riders can do what they choose, but there are two practical options, wear it all out and replace together or replace chains before anything else is worn. Doing something between those two has no advantage and will cost more in components than either.
There's Martin's middle way of swapping chains in and out at quite short intervals when his bikes ran with open chains, which substitutes maintenance time for components costs.
I'd forgotten that, it was very popular on derailleur set ups at one time, I even tried it once myself, but the effort to keep the wear in synch was two much for me.
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Thanks Mickeg, interesting ..
Effectively, for me 36x16, the most important gear is the first, i can climb almost any hill..
But, my next Surly chainring have 35 teeths, i got a good price for it, I don’ t know if i have to keep my sprocket in 16 teeths or maybe 17 ! but i'm afraid to ́lost my first short gear..
For information, 36x16 transmission, above 43km/h you can no longer pedal, sometimes it’s frustrating
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For information, 36x16 transmission, aboie 33km/h you can no longer pedal, sometimes it’s frustrating
Depends on your pedaling cadence.
I generally pedal relatively fast at about 90 rpm (tours par minute). With a 36x16 combination that translates into 36 km/h, which is way above a sustainable speed for me on the level, unless I have an exceptionally strong tail wind.
If necessary I can increase pedal cadence for very short periods. With a 36x16 combination at 120 rpm in the highest gear that would be 48 km/h. In practice, that kind of speed is not really useful for me, except perhaps when I negotiate medium size roundabouts, where I feel safer if I am doing roughly the same speed as most of the motor vehicules.
My current highest gearing on any of my bikes is 42x19 on my Rohloff equipped Raven Sport Tour. I use that bike mainly for day rides with little luggage. Top gear with 42x19 is slightly lower than with a 36x16, the maximum speed I managed recently when pedaling (downhill) was 53 km/h at 137 rpm, just to see if I could still do that at age 69. But normally I would just stop pedaling and coast down the hill.
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Thanks Mickeg, interesting ..
Effectively, for me 36x16, the most important gear is the first, i can climb almost any hill..
But, my next Surly chainring have 35 teeths, i got a good price for it, I don’ t know if i have to keep my sprocket in 16 teeths or maybe 17 ! but i'm afraid to ́lost my first short gear..
For information, 36x16 transmission, above 33km/h you can no longer pedal, sometimes it’s frustrating
My cadence has varied over time. For the past few years, it usually is in the range of 66 when I am doing a multi-hour ride. If I am working to get up a hill in a low gear, I try to raise it up to 72. But if I have been in the saddle for most of the day already, it might dip down to 60.
I mentioned I use 36T/16T (ratio of 2.25) for touring. But for riding around near home with an unladen bike, I put a 44T chainring one the bike, add four more chain links for a ratio of 2.75. For riding near home, I never need a gear higher than 14 with that higher range of gears.
But for touring, I value that low gear, so I can live with the loss of the higher gear that I would otherwise use on shallow downhills.
When I built up my Nomad, I calculated that if I wanted to use the stock 16T sprocket, pedal at a cadence of 72, and have a speed of 3.5 miles per hour, that I wanted a 36T sprocket. I find that I can't get below 3 mph without oversteering to try to maintain stability, both directional and vertical. And a cadence of 72 feels smoother than anything slower. My point is I did some calculations to figure out that I wanted the 36T, I did not pick it at random.
And the 44T, that range of gears pretty much mirrors my range of gears that I think are ideal for riding near home on my other bikes.
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I never thought about all that when making my choice, :)
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I never thought about all that when making my choice, :)
I am an engineer (retired), so I of course I tried to use a scientific approach. I tried to pedal up a steep hill near my home several times to see how slow I could go and still feel comfortable that I am stable and not oversteering and overcorrecting. That was how I came to the 3.5 mph criteria and the cadence of 72. If I tried a cadence closer to 60, I noticed the slow down and speed up pattern as I pedaled, thus I set my target for hill climbing at a cadence of 72 that felt smoother.
I have pedaled up hills on my Nomad Mk II in first gear with a cadence of 60, thus about 2.9 mph, but those were on good days without wind, minimal traffic on the road so I felt more comfortable being further from the edge, etc.
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I recently sought some advice re gearing down. The Clisham, my Hebridean nemesis means my 45 x 19 is a bit too much for me ( loaded Nomad etc.)
I’ve had the suggestion that dropping down to a 39T chainring and keeping the 19T sprocket will give me a couple of lower gears. I’ll give that a go and hopefully conquer The Clisham next time I’m there.
I haven’t looked into cadence etc.
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My other limitation is heart rate. If I pedal too hard, heart rate shoots up to levels I do not like to see it. I do not have heart problems and I want to keep it that way. So, I use a heart rate monitor to tell me when to stop, get off the bike, and walk it up the hill.
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For information, 36x16 transmission, aboie 33km/h you can no longer pedal, sometimes it’s frustrating
Depends on your pedaling cadence.
I generally pedal relatively fast at about 90 rpm (tours par minute). With a 36x16 combination that translates into 36 km/h, which is way above a sustainable speed for me on the level, unless I have an exceptionally strong tail wind.
If necessary I can increase pedal cadence for very short periods. With a 36x16 combination at 120 rpm in the highest gear that would be 48 km/h. In practice, that kind of speed is not really useful for me, except perhaps when I negotiate medium size roundabouts, where I feel safer if I am doing roughly the same speed as most of the motor vehicules.
My current highest gearing on any of my bikes is 42x19 on my Rohloff equipped Raven Sport Tour. I use that bike mainly for day rides with little luggage. Top gear with 42x19 is slightly lower than with a 36x16, the maximum speed I managed recently when pedaling (downhill) was 53 km/h at 137 rpm, just to see if I could still do that at age 69. But normally I would just stop pedaling and coast down the hill.
Yep, i did a mistake, 36x16 transmission, you can ride max at 43 km/h..
At 47km/h you pedal as a salade drainer
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On a loaded Nomad ( 45 x19 ) I did 46.6km downhill on Ardnamurchan in May. Still love the adrenaline rush and utter folly 😂
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On a loaded Nomad ( 45 x19 ) I did 46.6km downhill on Ardnamurchan in May. Still love the adrenaline rush and utter folly 😂
I only do the fast downhills on my derailleur bikes, not my Rohloff bike. Ratio of chainring to sprocket in top gear on my road bike is 50/12. My two derailleur touring bikes is 46/11, and my rando bike is 52/11.
But if I am going down a long hill, I let my cadence drop to a slower pace to relax and let gravity do the work.
The only time I put effort into pedaling on a downhill is if I am going down into a valley and several seconds later I will be pedaling up a steep hill on the other side. On those occasions I do that to help maintain momentum on the uphill.