Busted me teef

[onmybike]

Noticed a bit of crunchy grindiness on the road between Chitradurga and Hospet (India) the other day. I put it down to a dirty chain from riding about 20km on the powdery dirt verge to pass a truck traffic jam.

Gave the bike a nice clean in Hampi today only to find two broken teeth on the rear sprocket (Rohloff 16 tooth). Has anyone else had a similar problem? Cog has about 8000km from new and was reversed at 5000km. And by broken I mean sheared at the base of the tooth.

I've ordered a replacement from SJS today that hopefully will be waiting for me in Goa in a few weeks and I figure I'll last the distance til then as the planned route is largely flat until Goa. Otherwise all is running smoothly.

Syd

[geocycle]

I've not exactly broken any teeth, but mine are now filed like needles.  I reversed after 6700 miles and am now on 10,000 miles.  I've got another sprocket in the cupboard waiting to go on.  I think a consequence of the sharp teeth was that I broke another chain.  I had one of those half link chains on and being quite big it moved around quite a bit on the sprockets.  It got slightly slack and the sprocket worked through two links.
Good luck with refitting the new one.

[stutho]

Ouch!  Do you think that something got jammed between the sprocket and the chain, or is it just wear and tear?

My sprocket is still going strong at 16,000 miles  it got reversed at about 11500miles ( I think ).  At that time it was showing very little wear.  My chain ring on the other hand was almost shot.  I am pretty sure that I am going to were through side 2 of the chain ring before the spur gear dies but time will tell.

One other idea what size chain ring are you using?  Is it multiple of you chain ring?  (this can lead to odd wear pattens.)

 

[onmybike]

I can't figure out how or when the damage occurred - it was just the crunchiness and dust they made me have a closer look. For all I know one or both of the teeth may have broken any time in the last few months. The teeth aren't adjacent, there are two untouched teeth between them and you'd think if something got jammed hard enough to break the teeth it would have been noticeable to me whilst riding. I just put it down to s**t happening. So far it hasn't slowed me down but I worry if another breaks, especially one of the still standing in-between teeth it may lead to the chain derailing.

38/16 is the chain ring to sprocket ratio.

[gearoidmuar]

I broke the odd sprocket tooth on various blocks in  my time, but once when climbing a steep hill in Co.Kerry I sheared off 5 consecutive teeth on one sprocket.

[geocycle]

I broke the odd sprocket tooth on various blocks in  my time, but once when climbing a steep hill in Co.Kerry I sheared off 5 consecutive teeth on one sprocket.

+1

[onmybike]

Spares beat me to Goa by a few days but the bike/fitness shop in Panjim (Champs?) that sell western bikes had a chain whip far to short and wimpy for the task. Fortunately an Atlas/BSA dealer in Margao had a fancy new German bike tool set in the depths of his shop with a stonking great chain whip and spanner and the muscle power required too.

The crunchiness that made me notice the broken teeth btw seemed to have nothing to do with the teeth - it cleared up of its own volition over a few days, presumably once all the the dust and dirt had been ground away.

[mountaincarrot]

Good reminder Onmybike.
Mine are also like needles now, about 2mm thick - after killing 7 chains in 4000 miles, and reversed once. I have my new sprocket ready to go - perhaps I'd better get on with it!

[PH]

After killing 7 chains in 4000 miles,

I hope you've left a digit off there. a chain every 600 miles seems a bit extreme
Even every 6,000isn't that good,what chain are you using!  I've stopped counting since I stopped doing a regular long commute, but I don't think I've had a chain last less than 10,000 miles, with a lot of it on dirty track.

[Blacksail]

I had the same problem on a 16T, SJSC immediately sent me a replacement and the extractor tool.

This was Rohloffs response

"> I am sorry to hear that you have experienced a problem with one of our
> components. I understand that Robin Thorn has already supplied you with
> a replacement part so that you are back on the road quickly, I will
> contact him with regards to the guarantee claim.
>
> Let me assure you that this is by no means a regualar occurance. It is
> very, VERY unfortunate that this has happened, however we here at
> Rohloff are ourselves not able to guarantee to 100% that all of our
> components are of the same impeccable quality.
>
> Now and again there will always be the case that a failure could occur
> during one of the many manufacturing processes through which our
> components must go. In your case it seems as though the hardening
> process for our sprockets was not carried out sufficienty enough. This
> is unfortunately not something which we are able to check on every
> component as they arrive from our subcontractors.
>
> Again, please accept my appologies that this has happened to your
> particular sprocket. I am sure that the new one will deliver the
> expected performance.
>
> I wish you a good start in the new year.
>
>
> Best Wishes from Fuldatal, Germany."

[bike_the_planet]

I had the same problem on a 16T, SJSC immediately sent me a replacement and the extractor tool.

This was Rohloffs response

"> I am sorry to hear that you have experienced a problem with one of our
> components.

(etc etc)


> I wish you a good start in the new year.
>
>
> Best Wishes from Fuldatal, Germany."

You've got to hand it to Rohloff - in the rare event there's a problem, they're on to it.

I'm trying to remember the last time I received a nice letter from Mr Shimano...