Thorn Cycles Forum
Community => Thorn General => Topic started by: frog on October 26, 2007, 03:43:54 PM
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I bought a Rohloff chain for my Raven Tour at the end of Jan 2007 and have had 5700 miles out of it so far. I've just turned around the rings and cog to extend their life and I decided to check the chain with my Park Tool chain checker. I was very surprised to find the .75 end of the checker dropped into the gap in the links denoting, were it a derailleur chain, it should be changed.
Am I OK ignoring this test for the simple reasons my bike ain't a derailleur system and the chain is a Rohloff and should be measured with a Rohloff gauge?
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Yes & No. Yes you should ignore the test but not because you have a Rohloff chain (they are no different to any other chain).
I recently decided to change my chain after approx 3000 miles because it had worn to the point where it would be prudent to change it were it on a derailleur geared bike - big mistake. I found that changing the chain without changing/reversing the sprockets resulted lots of chain noise because the new chain was catching on the hooked profile of the sprocket teeth.
The best thing to do is to treat the chain, sprocket and chain ring as a set and run them in to the ground and only replace/reverse them only when seriously worn - if you run out of chain adjustment, remove a link. I would have thought that you should get more than 5700 miles out of your sprockets and chain ring, so might be tempted to swap them back to the worn side and continue using the original chain for a while yet.
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Thanks Goosander. I swapped the direction of the ring and the sprocket because of the noise I was getting. I did the sprocket this afternoon so I can't really say if I've done the trick or not. I'd like to think I'll get a few thousand more miles out of the current combination. Given it's £20 for a sprocket, £20 for a chain ring and £33 for a chain it won't give me a huge saving over a derailleur set up I was hoping for.
If that's the case perhaps I need to make the swap overs say at 4,000 miles and try to get a more even wear. But, I'll cross that bridge later [:)]
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Frog, are you saying that you originally reversed your chainring & sprocket because of transmission noise with the original chain? If so, I'm surprised because usually you would expect the chain and sprockets to wear together and 'play nicely'. In my case the noise was the caused by fitting a new chain to the part worn chainring & sprocket.
I'm not sure yet how long you should expect the transmission to last, but I'm hoping to get 8000 to 10000 miles before reversing the chainring & sprockets and fitting a new chain. I agree that the running costs aren't necessarily much cheaper than a deraillieur system but in my opinion the real benefit is the infrequent maintenance required.
If you want to save a bit of money, can I suggest using cheapo SRAM PC48 chains (£5 to £8) instead of rohloff ones as they last nearly as long. I have a rohloff chain on my mountain bike and whilst it seems to be more rust resistant than cheaper chains, it doesn't seem to last much longer, certainly not enough to justify the cost.
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When new the bike came with a SRAM chain. After 6 months I started to get a click so bought the Rohloff and the noise went away. All has been fine until a couple of weeks ago when I started to get some noise out of the transmission. I revesed the ring and most of the noise disappeared. I had to wait a week for my new chain whip arrive, a previous attempt at removing the sprocket destroyed my old one, and got it off in seconds with the right tools. I reversed the sprocket on Saturday and had a 45 mile ride this morning.
No noise at all!
I'm glad to say this has restored my faith in the longevity of the transmission. If this can be looked at as the 'halfway point' in the transmission history then things aren't as bad as I thought they might be.
I take your point about the life exptancy of the chain. This is something I'll have to keep an eye on in future.
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I had the same problem with chain whips, I broke mine twice trying to get the sprocket off my Raven. Unfortunately I used part of the old chain to fix the chain whip which meant I couldn't refit it to cure the transmission noise caused by the new chain/old sprockets. Instead I spent a fun couple of hours filing teeth on the sprocket to re-profile them, live and learn :-)
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quote:
Originally posted by goosander
Yes & No. Yes you should ignore the test but not because you have a Rohloff chain (they are no different to any other chain).
I believe that Rohloff chains have a tighter tolerance than Shimano chains. Even when buying new, the latter can already have up to 2 1/2 % stretch, menaing that the 3 1/2 % they reckon is the limit for derailleurs is already nearly there! Rohloff chains have up to 1.5 % stretch I believe.
But it shouldn't matter so much anyway. The reason that derailleurs are so sensitive is because since the invention of indexing in the '80s, the height of teeth on the rear sprocket has become a lot smaller to faciltate smooth, crisp gear changing. Even moderate wear will change this resulting in a steady deterioration of the smooth changing.
By contrAst if you look at a Rohloff sprocket you will see that the tooth height is far greater simply because the chain does not need to derail.
I wouldn't feel the need to change the chain just because the stretch limit for derailleurs has been reached.
Cheers
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Hi Frog,
Sorry I am late to this thread.
It's already been said by goosander but I would also treat the chain, chain ring, and sprocket as a set. Wear them into the ground and only then replace the chain and reverse the other 2. If you are getting noise from a set you may need to carefully remove some 'burs' from the chain ring or sprocket. This made a highly noticeable difference on my bike, however it is the sort of maintenance that is only needed every year or so.
My chain is now nearing 8000miles (95% on road). I am thinking that I will get between another 2 and 4 thousand out of it before I swap it out. My biggest problem is with surface rust! I have always looked after my chains and clean and oil them regularly, perversely I think that my cleaning schedule may have promoted the rust in this case. My derailer chains lasts me 3 to 4 thousand miles (with no rust). On the chain of my Raven I now use far more oil than the recommended one-drop per a link to hold the rust at bay. Part of my commute is on a 3-mile stretch of salt marsh, which floods regularly, probably why I get problems.
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Interestingly, I've just started having transmission problems on my Thorn Raven Enduro. It's 3 years old (I think) and maybe done 4000 miles max (bit of a guess) mostly off road. Everything was fine but the chain had gone slack so I tightened the eccentric bottom bracket and now the transmission feels and sounds bad.
I'm getting a grating feeling and clicking noise from the back. It seems to be coming from the chain where it engages with the back/bottom of the sprocket. The chain doesn't initially seem to engage with sprocket properly until it a further few degrees of revolution where it clunks into place on the sprocket - this seems to be the cause of the problem.
My first thought was that the sproket worn - there's definitely some wear on it (slight burs?) but it doesn't look too bad - and I've had expected it to last longer. The front chain ring looks fine. I tried removing the sprocket and predicatably it's stuck fast - will have to go to a bike shop to get them to clamp it in a vice if it needs to be reversed :-(
But I now think that the chain has stretched and needs to be replaced. I can pull it away from the front of the chain ring - which I seem to remember from my derailer days was a good indication of a chain needing to be replaced? Strangely the chain that came with the bike appears to be a nine speed chain - which isn't good?
So I'd usually agree that the whole chain/sprocket/chain ring should be treated together and my plan was to run the whole lot into the ground. But to me it looks like I just have a nackered chain. Thinking of trying a new SRAM PC 68 8sp chain to see if that just resolves my problem - will tell you how it goes...
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Maybe you tensioned the chain too tight?
I had no chain whip to remove the sprocket and the shops were closed. I made one with an old chain & flimsy bar, but the sprocket wouldn't move. So I heated the sprocket gently (didn't want to damage plastic/rubber components) with a small blow lamp flame, let some release oil soak into the sprocket thread overnight and unscrewed it easily with bare fingers, the next morning!
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Peterh
I realise that you didn't put it on but another 9 speed chain fitted on a Speedhub!!! I wonder if it is the original chain, I can't imaging SJSC fitting a 9 speed chain so the next chain might be the 3rd chain the hub has seen.
Are you sure that you didn’t overly tighten the chain? If it sounds and feels bad you may need to give it a bit more slack. Much better the chain is too slack than too tight.
I can vouch for the PC 68 I use this chain on both the my Rohloff equipped bikes.
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Stutho,
Sram PC99 9 speed chain came fitted on my brand new Raven Tour,and yes, I've had some minor clicking problems!SJSC must think they're OK though.
Pallium.
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Yes - the chain is the original from SJSC - SRAM PC95 I think. I'm pretty careful about the chain tension - not too tight and never had any problems before. SJSC tensioned my chain when I took the bike back after I had a problem - and they seemed to make it very tight. I find it behaves better if there's a bit of slack - if you can push the chain in at least a centimeter it usually seems ok. We'll see how a new PC68 behaves.
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Seems strange SJSC are now using a 9 speed chain which must be narrower (=weaker?) than an 8 speed equivalent. My 14 month raven tour came with a PC48 that I swapped to a PC68 about 6 months ago in an attempt to narrow down a clicking problem. The problem turned out to be the eccentric and not the chain, but I left the PC68 on anyway as i like the nickel plating. I initially set it quite tight but it quickly stretched. I will now not adjust the eccentric until the chain begins to jump off. It did come off once recently on a very rocky downhill but I think it will be fine for a good few k miles yet.
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An extract from the Rohloff speedhub manual (page 45):-
quote:
All 1/2" 3/32" eight speed chains are suitable for use with the Rohloff Speedhub 500/14. With the Rohloff SLT-99 chains, both the eight and nine speed versions can be used. This is because the Rohloff SLT-99 chains are less elastic, and therefore, causing less wear on the chainring and sprocket due to their identical link plates. All 1/2" 1/8" bicycle chains are compatible with the Rohloff Speedhub 500/14 sprockets. However, these thicker
chains are by no means stronger and not recommended for use with the Rohloff Speedhub 500/14. In addition to this, they are too wide to pass through the Rohloff chain tensioner.
Having said all of that if SJSC are fitting certain other 9 speed chains then it is a fair bet that it reality it is safe to do so. SJSC have sold literally thousands of bikes - they know what they are doing.
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It's easy to be too particular when it comes to chains, especially if you've had a lot of experience with derailleurs. Best to forget everything you've learned and keep running them till they're knackered. I'm using a £10 single speed chain, it has a tough looking anti-rust coating, rarely gets cleaned, oiled with 3in1 when it squeaks, tightened when it looks like it's in danger off falling of and has never given any trouble. This is why I have a Rohloff, if I wanted to spend time cleaning and adjusting I'd have stuck with derailleurs[;)]
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Oh no! There I was thinking the drive chain would all be nice and easy to maintain (especially compared with derailleurs), but the posts in this forum make it seem very complicated, difficult to get right, and not necessarily very long lasting. I hope I am only reading of rare problems that people have had!
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Hmm, well I fitted a new chain and everything is fine. I haven't given it much attention in the last 3 years, cleaned it occasionally, dribbled some oil on it when I remembered - tightened it a few times a year. Definitely easier than my last bike with a derailier. A new chain every three years isn't bad I think.
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I've done about 3000 miles on the new chain and it's starting to sag quite a bit; guess there's some life in it yet though. Do Thorn fit a Rohloff chain to the new bike? (Raven Tour) or is it an extra - can't remember. I haven't turned the cogs yet - should I do that now?
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Hi David, Just had a look at your blog -looks great. I can see that being a regular read as I eat my lunch!
The rohloff chain is an extra, my RT came with a SRAM PC48 which I've since upgraded to a PC68.
There seems to be two schools of thought regarding chain and sprocket life. I now subscribe to the 'leave well alone until it falls off view' -this has taken a while to get used to as I had been an avid chain fettler on my derailleur bikes. I assume you've tightened the eccentric to remove the worse of the sagging chain? According to the literature you should expect more than 3k miles before you need to reverse the sprocket (I think i read 10k miles somewhere). I guess yours is pretty heavy duty use though! I'd be tempted to change the chain half way -Cairns has some good bike shops - and if it seats OK on the sprocket leave it as it is, otherwise reverse it at that time.
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SEE OTHER THREAD, but yes, heavy use alright, and I only got 6000km on sprockets and chain. I did clean the chain 2 or 3 times but maybe ought to do that more.