Thorn Cycles Forum
Community => Thorn General => Topic started by: in4 on April 03, 2025, 08:34:07 PM
-
Approximately how many kms should a sprocket last? Ive got some wear on my 45 x 19 combo but it looks good to go for quite some kms yet before it needs reversing/changing. TIA
-
Approximately how many kms should a sprocket last?
Depends on lots of things - weather, riding on clean roads or dirty tracks, use of a chaincase or not.
I haven't yet done enough distance with Rohloff sprockets to know, and they are under ChainGlider chain cases that protect the transmission fairly well against mud, sand and other debris, so they should last significantly longer than with an exposed transmission.
Before I started using ChainGliders, with similar size sprockets (19 to 22 teeth) used on Sturmey hubs I used to get about 5,000 kms before flipping the sprocket, so about 10,000 kms in all. This is in a relatively wet coastal climate, sometimes with sand, salt or mud, but not doing much mountain-bike style riding.
-
Approximately how many kms should a sprocket last?
I’ve got the same combo and am wondering the same. 18000km so far and haven’t flipped. No chainglider.
-
Are you running sprocket, chain and chainring into the ground. to be replaced together? If so, flip/change when the sprocket teeth are noticeably shark fin like, as martinf says that depends on several factors, for my riding it#s probably 20 - 25,000km in all weathers.
Or, are you changing chains as they wear in order to prolong the life of the other components? If you're doing this right, the sprocket life in 100's of thousands of km, though you'll be getting through a lot of chains.
-
Approximately how many kms should a sprocket last? Ive got some wear on my 45 x 19 combo but it looks good to go for quite some kms yet before it needs reversing/changing. TIA
Keep going, but don't flip a sprocket until you replace the chain.
On my Rohloff bike, I wait until a bit over 1 percent for my chain.
I agree with Ph, but I a get less distance than he does.
-
If the sprocket is wearing, how is the chainwheel?
-
If the sprocket is wearing, how is the chainwheel?
I flip/replace mine at the same time, as recommended in the Living with a Rohloff booklet. It's not as worn as the sprocket, but probably has enough wear to increase the wear rate of a new chain, IMO it's a false economy to keep it. So that's 2 chains, 1 sprocket and 1 chainring per 40,000+ km, about £100. Considering how little else gets spent on it, I can live with that. For me, the same usage on a derailleur tourer would be three or four times the cost and a lot more time in maintenance.
-
Hi PH.
Maybe I have misunderstood but it sounds like you flip both the sprocket and chainwheel at the first chain change and replace them at the second chain change?
What % elongation do you change chains?
You seem to get good chain mileage running without a chaincase.
-
Hi PH.
Maybe I have misunderstood but it sounds like you flip both the sprocket and chainwheel at the first chain change and replace them at the second chain change?
What % elongation do you change chains?
You seem to get good chain mileage running without a chaincase.
You've understood it right.
I don't measure the chain, what's the point? I'd do so on a derailleur where I was sacrificing chains to save cassettes. But with any single chain line, I'm accepting they'll need replacing together. I'm judging when to replace based on wear to the sprocket.
I'm also, where possible, using the biggest combination of chainring and sprocket, for example 19/48 is almost identical to 16/40, that not only spreads the wear over more teeth, it also means more links are engaged and the bend between them is less, the latter will also increase efficiency. You'd need a lifetime to accurately measure how much difference these things make, IMO it isn't insignificant. I'm not obsessive about chain cleaning, but it's always well lubricated.
I'm not a fan of chaincases, I like to keep an eye on the transmission and all those I've seen add complexity to wheel removal. I have no doubt though, that with the right chaincase, where a chain was kept clean and protected from the rain, and well lubricated, you could double or triple the mileage I get.
-
Apologies for the late response. Many thanks for all the replies. I’m on my first cycle-camp of the year.
I’ve attached a couple of photos for further info. Apologies for the dirt, the tracks are still quite wet in places.
-
Apologies for the late response. Many thanks for all the replies. I’m on my first cycle-camp of the year.
I’ve attached a couple of photos for further info. Apologies for the dirt, the tracks are still quite wet in places.
Looks fine to me, other than the chain looks a bit dry (It might just be the photo) I wouldn't be considering changing yet.
-
...
I'm also, where possible, using the biggest combination of chainring and sprocket, for example 19/48 is almost identical to 16/40, that not only spreads the wear over more teeth, it also means more links are engaged and the bend between them is less, the latter will also increase efficiency. ....
There is a third advantage to the way you are doing it, a bigger chainring means that you put less tension on the chain. Thus, there is less pressure at the wearing surface where you have metal rubbing on metal, less pressure means less wear.
-
Apologies for the late response. Many thanks for all the replies. I’m on my first cycle-camp of the year.
I’ve attached a couple of photos for further info. Apologies for the dirt, the tracks are still quite wet in places.
I agree with PH, those teeth look very good.