When to reverse and change chainring, sprocket and chain?

[crazytraveler]

How many kilometers approximately should you ride before you start doing this procedure.

In which order is it supposed to be done?

I have to make an order from SJS cycles -and wait- and I was thinking if I should order something else... I don't know how easy will be to find sprocket, Rohloff oil, chain or chainring on the road. We are in Slovenia, cycling through the Balkans directions Turkey (maybe there I will find everything?) and after that into Central Asia.

We have ridden 10.000 Km with our Thorn Nomads since we bought the bicycle and the only maintenance we have done is to clean and oil the chain once in a while, clean and grease things when tighten up and change oil of Rohloff hub. We are using KMC Rohloff-specific X1 chain.

Here is a picture of my chainring and sprocket attached.

[crazytraveler]

Added picture of the sprocket as well.

[il padrone]

How many kilometers approximately should you ride before you start doing this procedure.

My Thorn Nomad has done just under 21,000 kms. It is still on the first chainring and sprocket, but the third chain on its last rotation. It will be about 24,000 kms before I replace all.

In which order is it supposed to be done?

There is no real order, but generally a chain will wear out before the sprocket. But if you let it go too far (over 1/8" stretch in 12") then the sprocket will be too far gone to mesh happily with a new chain. Chainrings last a lot longer as they have more teeth to share the wear over.

I have to make an order from SJS cycles -and wait- and I was thinking if I should order something else... I don't know how easy will be to find sprocket, Rohloff oil, chain or chainring on the road. We are in Slovenia, cycling through the Balkans directions Turkey (maybe there I will find everything?) and after that into Central Asia.

Order these ahead where you can. You will not find them on the road in the Balkans or Turkey (nor even in their bike shops too much). These are very much specialist items, even in the UK and Western Europe.

[crazytraveler]

My Thorn Nomad has done just under 21,000 kms. It is still on the first chainring and sprocket, but the third chain on its last rotation. It will be about 24,000 kms before I replace all.

Third chain? One every 8,000 Km? How do you check when do you need to replace it? Are you using the same chains than I do?

There is no real order, but generally a chain will wear out before the sprocket. But if you let it go too far (over 1/8" stretch in 12") then the sprocket will be too far gone to mesh happily with a new chain. Chainrings last a lot longer as they have more teeth to share the wear over.

How do you check that?

Order these ahead where you can. You will not find them on the road in the Balkans or Turkey (nor even in their bike shops too much). These are very much specialist items, even in the UK and Western Europe.[/quote]

Chainring is standard enough, right? You don't need to order it online.
Sprocket sounds most likely...
Rohloff oil?

Cheers!

[mickeg]

Sheldon Brown website as a lot of good general information that you may find helpful in your travels.

Specific to chains and chain wear:
http://sheldonbrown.com/chains.html

He recommends (I pasted from that page, following numbers are based on 12 inch length):

 -   If the link pin is less than 1/16" past the mark, all is well.
 -   If the link pin is 1/16" past the mark, you should replace the chain, but the sprockets are probably undamaged.
 -   If the link pin is 1/8" past the mark, you have left it too long, and the sprockets (at least the favorite ones) will be too badly worn. If you replace a chain at the 1/8" point, without replacing the sprockets, it may run OK and not skip, but the worn sprockets will cause the new chain to wear much faster than it should, until it catches up with the wear state of the sprockets.
 -   If the link pin is past the 1/8" mark, a new chain will almost certainly skip on the worn sprockets, especially the smaller ones.

I usually replace chains when I get to about 3/32" using a 12 inch stainless ruler.  My experience on worn cogs is from derailleur bikes, not IGH bikes.  So, I am not commenting on when to replace chainring and cogs. 

Sometimes you will see recommendations based on percentage "chain stretch", an eighth inch "stretch" over a distance of 12 inches is very close to 1 percent, 3/32 inches roughly 0.75 percent.

How easy is it to find a new chainring where you will be?  I have never been there so I do not know, but I like you think that this is a standard bike shop item for better shops, especially if it is a 5 arm road 110mm or 130mm bolt circle diameter chainring.

Chains, especially the cheap ones are cheaper than sprockets and chainrings.  So I buy cheap chains and change them often enough that I have not had to replace any chainrings or sprockets in many years.

[crazytraveler]

I got lost in the explanation. Numbers in inches didn't help either. :-P

I google around in cm and found this, no idea if this is useful for my kind of chain.



Measuring like that, 10 pins in the middle and counting until the beginning of the next pin (not the center of them), mine measures 132mm, in which case it still have some further use I guess.

Am I right?

[crazytraveler]

Now I measured 10 whole links (from the centre of the pin) and it is 25.75 cm.

I think that would be an 8% extension?

[crazytraveler]

Assuming I need to change the chain, the sprocket and chainring look alright. Am I wrong?

Should I reverse only the sprocket when I change the chain? The chainring as well? Or only change the chain and that's it?

[geocycle]

The chainring and sprocket looks fine to me. I changed mine after 15000 km. in that time I'd probably use 2-3 chains. Much depends on the type of riding with dirt tracks being particularly bad. Even after 15000 it was still ok but it made sense to change. You could get longer life by rotating the sprocket and chainring. I'd definitely carry a sprocket and the special removal tool. Chain rings last longer and you have more chance of finding something compatible (note there a lot of variations in teeth and diameters) but plan ahead to when you are in a major town.

Did you get the forks fitted?

[crazytraveler]

The chainring and sprocket looks fine to me. I changed mine after 15000 km. in that time I'd probably use 2-3 chains. Much depends on the type of riding with dirt tracks being particularly bad. Even after 15000 it was still ok but it made sense to change. You could get longer life by rotating the sprocket and chainring. I'd definitely carry a sprocket and the special removal tool. Chain rings last longer and you have more chance of finding something compatible (note there a lot of variations in teeth and diameters) but plan ahead to when you are in a major town.

Did you get the forks fitted?

Thanks!

Yes, I got the fork fitted and direction in the bike is normal again, not falling to one side!

Did you change the sprocket? Or the chainring too?

By your comment I think I could change the chain and rotate the sprocket (I have one spare one and the tool to remove it), but keeping the chainring as it is. What do you think?

[geocycle]

Glad the fork fitted ok and the problem solved!

Yes, switching the sprocket should help extend its life. I don't think it's gone too far. The trick is changing chain and sprockets when they are still compatible, if either gets too worn for the other they won't mesh.

Personally, I changed everything (twice now) but not on tour like you.

[il padrone]

Third chain? One every 8,000 Km? How do you check when do you need to replace it? Are you using the same chains than I do?

I'm using the KMC X8 chains. I check them by measuring a 12" length. Use a steel ruler (you can get all sorts of chain-checker gauges, but a simple ruler is easy and more accurate). At 1/8" elongation it is time to replace

Chainring is standard enough, right? You don't need to order it online.
Sprocket sounds most likely...
Rohloff oil?

You can use a standard chain-ring, but I have been using the Thorn ring (thicker, double-sided, can be reversed for twice the life). Next chain-ring will be the Surly stainless steel ring and it will be used with a Hebie Chainglider to protect from dirt.

The sprocket is a Rohloff sprocket so not able to be bought just anywhere. The oil for the hub is Rohloff oil and I would carry a oil-change kit if I was likely to be on tour when the change-over time came around. Again, needs to be purchased from specialised suppliers.

[il padrone]

Now I measured 10 whole links (from the centre of the pin) and it is 25.75 cm.

I think that would be an 8% extension?

8%  

The standard elongation marker for chain replacement is 0.75%

10 links is 10". This is 25.4 cms and if yours measures 25.75 cms you have 0.35 cms stretch (0.35%). Still OK.
[edit] This is incorrect.

[crazytraveler]

8%  

The standard elongation marker for chain replacement is 0.75%

10 links is 10". This is 25.4 cms and if yours measures 25.75 cms you have 0.35 cms stretch (0.35%). Still OK.

No idea what I did...

But here: http://sheldonbrown.com/chains.html it says if it is 25.7 it means you left it too long already.

What is it then?

[il padrone]

OK, yeah. Sorry I was thinking wrongly there.  

25.59 cms is already 0.75% elongation. So your chain (25.75 cms) is worn and will need a matching new sprocket when you replace it.... most likely.