sprocket reversing problem anyone?

[jawj]

What a strange mix of experiences we seem to have. I too, Redcogs, would like to know how many miles you've had out of your sprocket. I reckon I've done about 8,000 miles, though I must admit the sprocket is not completely worn out on that side. The bike's getting a new chainring and cranks so I thought I'd give the sprocket a fresh face to work with as well. (Not that there's anything wrong with the old chainring either, it's just moving onto pastures new on a different bike.)

I am intrigued to know what chain cleaning regime/methods you follow, Stu, to get 12,000 miles out of a chain. I'm impressed! I've done less miles and changed my chain a couple of times and yet my sprocket was noticeably, but as I say not completely, worn. The chainring, on the other hand, doesn't seem too badly worn at all, certainly less than the sprocket.

Ooh er, there's some spooky stuff going on here...

[pdamm]

I guess what I’d really like to know is how long I can leave a chain on for until it becomes a problem.  Having the teeth on the sprocket break off when you are trying to remove the sprocket is certainly a problem! 

I recently asked Rohloff that question and was told that the standard limits that apply to derailleur equipped bicycles also apply here.  I tried debating the point with them but go nowhere.  I also didn’t get a lot of reasoned response to my arguments so I suspect the person I was dealing with was not all that technical.  The experience of many members of this forum contradicts the advice I received from Rohloff.  What I was told however was that since we need to use a chain whip to remove the sprocket, a worn sprocket risks the chain whip not being able to grip the sprocket properly.  It seems that Redcogs experience is that the teeth may break off before the chain whip slips. 

I must admit I have been trying to work out how to get a sprocket off without a chain whip in case I find myself in the same situation as Redcogs but end up breaking all the teeth!

This rider had a different sort of problem after 18,000 km when the chain started to slip on the sprocket.

http://www.crazyguyonabike.com/doc/page/?o=3Tzut&page_id=74593&v=5u

I am up to ~21,500 km on my Raven Tour.  I reversed the sprocket at about 9,800 km and replaced the chain.  Since then my chain has done ~ 11,700 happy km and has elongated by 3/16 inch over 12 links (i.e., 3 times the recommended limit for derailleur equipped bikes).  The sprocket looks ok but my sprocket ware indicating tool (from Rohloff) says it is way past it.  I am not a mechanical engineer and for a part time handyman, experience has taught me that I am much better off sticking to my day job.  My gut feel is that it is ok to keep going for a while but how long? – is it ok for it to be worn by 4/16’s or 5/16ths I am not sure.

For those who are interested I oil my chain with White Lightning after about 4 to 5 hours of riding.  I have never cleaned my chain.  It is a bit mucky but the WL falls off after a while so the muck levels have long since stabilised.  I am sure there are better ways to look after a chain but this is what I do.

Does anybody else have any measurements for how much their chain had elongated when they finally retired it – and how easy was it to remove the sprocket?

If enough of us can contribute some measurements, over time we should be able to come up with some sort of recommendation for how much a chain can elongate before it is time to change the chain and reverse the sprocket.

Peter

[stutho]

Just in from the garage after measuring my old chain - yet to find it way to the bin!  The result was a little of a surprise.  The extension was a little over 1/8" say 5/64" in 12 link (a bit more than 1%).  It is cold and I only took the one measurement (I will try again tomorrow to confirm).  I was expecting it to be more.

I ride a 42T/16T  The Chain ring is Blackspire  Downhill which like I said previous is very worn on one face after 12,000.  I will be very happy if I get the other side to 10,000miles.  The Spur gear is looking in remarkably good condition it is NOT hooked but the end of the teeth are slightly chamfered.

The chain was an SRAM PC68 with a powerlink and my lube of choice Rohloff (I sometimes stray).  I can never make my mind up on chain cleaning.  Sometimes I shake the chain up in white spirit followed by shaking it up in a 50% dilute mix of mucoff (I am sure  any modern degrease would work)  followed by a rinsing in water and drying in the oven - I have an understanding Wife.  I re-oil the chain while it is still warm so that I get the maximum penetration. However I am not convinced the all this effort is worth it  - I also think it promotes rusting,  the PC68 is plated on a standard chain the risk of rust would probably out way any gain of a clean chain.  So... I sometime think that just wiping the chain down (very thoroughly) and re-oiling  is just as affective, recently this method has being getting my vote more and more.   I use baby wipes to do the wiping down. 

I am going to say again that nearly all my miles are on road,  offroader would get less mileage.  When the chain ring gives up the ghost (hopefully in 3 years time) then I am going to switch the lot out inc the spur gear.  Ideally I will be getting stainless steal chainring, Surly make them but only in 5 bolt - typically I got a 4 bolt spider - but I digress.

All the best

Stutho       

[davefife]

I just "reversed" this afternoon - 9,000 miles.  All was so easy   Especially after some the anxiety inducing tales told previously.  I used the by the book method with the 24mm spanner on the hub tool and a standard chain whip.
Also reveresed the chainwheel and fitted my first new chain.

[geocycle]

Nice one Dave, good to hear of someone with a success story!  I had mine reversed by SJS while I was having some new rims put on.  I might try and do it myself next time.  When you've reversed it will it come off clockwise or anticlockwise next time?  I can't visual the threads.

[davefife]

you should do it yourself, its not difficult!  Your thread question is a misnomer as the sprocket is threaded the same way from both sides - a standard clockwise - its not threaded clockwise from one side only.  The best way to find your way in mechanicals and basic engineering principles is to have a go, a good set of quality tools are essential, then any manual (on line or paper from the library) to familiarise yourself, then go ahead and get a feel for it on your own bike.
Zen and the art of motorcycle mainatainance is a good read to understand how parts move and wear and give you an understanding of how to feel the machine adjusting and changing.  Context is everything!

For those trying to estimate chain life, mine was 9,000 miles, i reversed it at 4,000 and took out a link at 5,500. 

[geocycle]

Thanks for clarifying the threading.  I probably would have had a go at the sprocket myself except that I needed a new rim anyway and wasn't confident I could make a good job of the rohloff on what would have been my first wheel build.  Also, the stories on here suggested my tools were not up to the job -I'd have needed the rohloff tool and possibly a stronger chain whip.

My sprocket was showing some wear (wave profiles) after about 6000 miles.  It could probably have done another 3000 but I decided to have it reversed anyway while it was at SJS.  I swapped the original chain for a stainless version after 1500 miles, then broke this repalcement recently after it had done another 5000 miles, and I am now back onto the original.  I shall replace it with a new one next time I'm tinkering with the bike and keep the original as a backup.

[pdamm]

I have just replaced the rear sprocket, front chain ring and chain on my Raven Tour.  It turned out to be an easy job.  The chain had just over 16,500 km on it and had elongated to almost a ¼ inch over 12 links.  The teeth on the rear sprocket were worn down to about 3/5 of the width of the teeth on the replacement.  I had no problems getting the sprocket off with a chain whip and spanner just like the manual says.  One interesting thing was the chain had started sticking a little.  It wouldn’t flop loosely at each link, some of them stuck a little even with lots of lube applied.  With the chain tension now quite slack it gave the chain line a zigzag look in a few places. 

Peter

[geocycle]

Finally, changed my sprocket after 10,000 miles.  It was reversed after 6000.  It had worn to fairly sharp points and I think was leading to my having problems with broken chains.  Tried the 'rowing' method but couldn't move the sprocket.  Then broke my chain whip (cheap halfords), then got a friend around with a better one and between us we managed to shift it.  All running smoothly again, although I might replace the front chainring before the chain wears again.  Like all these more technical jobs on the bike they are not nearly as bad as anticipated.

[Cake]

Thats good to hear Geo - i'm going to reverse mine for the first time when the chain needs tensioning next (1500 miles or so and the chain will be replaced and chainring reversed).

I'm not expecting it to be terribly willing to part from its current position due it having been there for 11000 miles....

[geocycle]

Thats good to hear Geo - i'm going to reverse mine for the first time when the chain needs tensioning next (1500 miles or so and the chain will be replaced and chainring reversed).

I'm not expecting it to be terribly willing to part from its current position due it having been there for 11000 miles....

Wow, that's a lot of miles on one small sprocket!  It is amazing how different they wear.  There would literarly have been nothing left of mine had I waited that long to reverse.  I'd have a new sprocket in reserve in case the new chain doesn't mesh with the reversed sprocket.  Good luck!

[Cake]

I think i'll need a bit of luck!

I only use the RT on tarmac and clean the chain pretty regularly so perhaps that is a factor.

Being a prepared sort, i have a spare chain, chainring and sprocket just in case.... Well, it wouldn't be right having to wait for parts and not being able to ride it!

[stutho]

Wow, that's a lot of miles on one small sprocket! 

I too got 12,000 miles out of one side of the sprocket - and one chain.  I think PH may have got even more!

[geocycle]

I think i'll need a bit of luck!

I only use the RT on tarmac and clean the chain pretty regularly so perhaps that is a factor.

Being a prepared sort, i have a spare chain, chainring and sprocket just in case.... Well, it wouldn't be right having to wait for parts and not being able to ride it!

Yes, I ride a fair bit offroad and probably don't clean the chain often enough.  In those 10,000 miles I have broken three chains!  The first was a PC68 which suffered a bizarre breakage of 3 internal links reported elsewhere http://www.thorncycles.co.uk/forums/index.php?topic=1934.0.  I think it got munched by the chain ring when running it a bit slack.  Then I tried a half link chain which never really seated well on the worn sprocket and attracted grit like there was no tomorrow.  It fell apart, was repaired twice and then finally the out links broke.  The original PC48 went back on for the winter and broke two weeks ago -again a fracture in an external plate.  I'm hoping the new sprocket will help and I'll order a new chain ring although this looks OK.

[Cake]

Yesterday afternoon was spent rejuvenating the transmission on my RT.

After 12000 road miles the chain was very slack and the teeth on the rear sprocket were taking on a very wave-like appearance, although the wear on the chainring was hardly noticeable at all.  Also, despite the miles, the E.B.B. was just over halfway through its allowable adjustment - so the £4.99 KMC Z51 is not prone to too much "stretching" for my type of use.

I secured the chain whip to the sprocket with a few cable-ties and was quite surprised when it (the sprocket) loosened off - i was expecting much more resistance after reading about the many trials others had been through. I used a bit of very fine and used wet and dry (wet) and lightly pushed the face of the sprocket around on it under its own weight.  This soon got rid of the staining / crud on the surface that would be in contact with the oil seal.  A bit of copper grease on the thread and a smearing of hub oil on the oilseal face and the sprocket was reversed.

After reversing the chainring i refitted the back wheel and fitted a new Z51, using the original indents in the E.B.B. (hopefully this will also have reduced the stress / wear on the rather loose fitting thread / set screw arrangement).

A flush and an oil change later (i drained the oil before removing the sprocket to avoid a slick) and i now have one super smooth riding RT - sweet.

Overall i found this very straight forward - not nearly as problematic as i was expecting and hopefully the sprocket will last another 8000 miles or so.  Brilliant.

As an aside, i was tempted to replace the Marathon Plus while the wheel was off, but despite 12000 miles it still has a couple of thousand miles left in it i think.  I'll use it until i get a (first!) puncture and then bin it.