Author Topic: Rohloff sprocket wear  (Read 3094 times)

julio

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Rohloff sprocket wear
« on: February 16, 2019, 11:16:46 PM »
As you can see on the pics one sprocket is new and other is well worn (around 16000 kms).
But i'm planning to ride again with the used one and it is for that reason it don't want to change my chain by a new one (usually i replace chains every 5000 kms), i think it is no longer necessary.

Until which limit it is better to replace the sprocket ?




geocycle

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Re: Rohloff sprocket wear
« Reply #1 on: February 17, 2019, 11:22:59 AM »
A new chain would not be compatible with that worn sprocket. I would continue to use the old chain and sprocket until you have problems of the chain falling off, then Id change both together. You should also consider your chain ring and I would probably reverse it when you fit the new chain and sprocket.
 

julio

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Re: Rohloff sprocket wear
« Reply #2 on: February 17, 2019, 12:06:14 PM »
Fine, i'm going to do like that.
Otherwise, when i replaced my last chain (5000 kms ago) i had a horrible noise of transmission, probably the problem came from my sprocket..), the noise has disappeared around 200 kms later.

martinf

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Re: Rohloff sprocket wear
« Reply #3 on: February 17, 2019, 11:35:17 PM »
I would continue to use the old chain and sprocket until you have problems of the chain falling off.

Or perhaps the teeth on the sprocket breaking off.

Another thing to consider is having the tools/spares to do the sprocket/chainring/chain change. The most difficult step will be removing the rear sprocket, it might be easier in a place where you can find a garage with a large vice or a really big adjustable spanner rather than somewhere out in the wilds.

mickeg

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Re: Rohloff sprocket wear
« Reply #4 on: February 18, 2019, 01:25:05 AM »
...
Another thing to consider is having the tools/spares to do the sprocket/chainring/chain change. The most difficult step will be removing the rear sprocket, it might be easier in a place where you can find a garage with a large vice or a really big adjustable spanner rather than somewhere out in the wilds.

I do not know if this is a valid assumption or not when dealing with bike shops in developing countries, but I assume that most bike shops will have a large wrench or vice and will have a chain whip.  But, I assume they will not have the special Rohloff tool for sprocket removal, so I carry that Rohloff tool but not the other stuff.

macspud

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Re: Rohloff sprocket wear
« Reply #5 on: February 18, 2019, 07:28:51 AM »
I would continue to use the old chain and sprocket until you have problems of the chain falling off.

Or perhaps the teeth on the sprocket breaking off.

Another thing to consider is having the tools/spares to do the sprocket/chainring/chain change. The most difficult step will be removing the rear sprocket, it might be easier in a place where you can find a garage with a large vice or a really big adjustable spanner rather than somewhere out in the wilds.

I find a large stilson works well in place of a chain whip. I tried with a chain whip and just snapped the chain then tried with a large stilson and the sprocket came off no problem. I was initially worried that the stilson would damage the strocket but it didn't at all.   

martinf

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Re: Rohloff sprocket wear
« Reply #6 on: February 18, 2019, 09:32:00 AM »
I do not know if this is a valid assumption or not when dealing with bike shops in developing countries, but I assume that most bike shops will have a large wrench or vice and will have a chain whip.  But, I assume they will not have the special Rohloff tool for sprocket removal, so I carry that Rohloff tool but not the other stuff.

I assume the same thing.

I don't do developing countries, but in the European countries I have visited small motor vehicle garages and places dealing with agricultural machinery are much more common than bike shops and I reckon they should also be able to remove a Rohloff sprocket so long as I provide the special Rohloff tool.

mickeg

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Re: Rohloff sprocket wear
« Reply #7 on: February 18, 2019, 03:26:58 PM »
..., but in the European countries I have visited small motor vehicle garages and places dealing with agricultural machinery are much more common than bike shops and I reckon they should also be able to remove a Rohloff sprocket so long as I provide the special Rohloff tool.

In the more advanced economies like Europe, I would try to find a bike shop if my Rohloff needed help.  I do not let my sprockets wear to the point that Julio has, thus if I needed the sprocket removed it would be because the hub inards are the problem, in which case my problems are pretty sizeable.  I do not do extremely long trips where that much sprocket wear would occur during the trip. 

If my wheel had to be shipped to Rohloff or some other shop, or if a new internal mechanism could be provided by Rohloff, I am assuming that I would rely on a bike shop for assistance.

I made the comment about developing countries because if you are in one of them, you are more likely to be doing the high distances where you might need to flip your sprocket.  But if you were there, you might have been better off if you switched to spline carrier before your trip.

julio

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Re: Rohloff sprocket wear
« Reply #8 on: February 20, 2019, 05:42:17 PM »
I made my chain whip, in aluminium for more lightness. So when i need flipped the sprocket, i just ask in a garage a appropriate tool (best is a large key in 24)

But i'm just thinking if my sprocket is too much worn (as a cat teeths), could i disassemble it ?  :o

mickeg

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Re: Rohloff sprocket wear
« Reply #9 on: February 20, 2019, 07:23:12 PM »
I made my chain whip, in aluminium for more lightness. ...

But i'm just thinking if my sprocket is too much worn (as a cat teeths), could i disassemble it ?  :o

Decades ago (the era of freewheels instead of cassettes) I made some chain whips, I could not afford to buy the real thing.  Back then if you wanted to custom build a freewheel for different gearing, you needed a couple of chain whips, as at least one of the sprockets would be threaded onto the freewheel body.  I badly bent them even though they were made of steel.  If you are trying to remove Rohloff sprocket with a DIY whip that you fabricated, I wish you luck at the time when you actually need that luck.

Or, if your chain whip is only to remove a cassette so you can fix a spoke or something, there are simpler ways to do that.  I made one that was less than 50 grams, it was a short bit of chain and a cord that you can tie off to the rim.  See photo.  Some people put their cassette retaining rings on really tight, if you wanted to use a whip substitute like mine, make sure it will work at home first, just in case you need a real whip.

I have also heard of people using a nylon strap (from their luggage) or some light weight rope to serve a similar purpose.

Speaking of whips, something I started to do a few years ago - when you are working with a chain whip, the end of the chain often falls from the sprocket and is quite inconvenient.  I bought some tiny little very strong magnets.  I use a small magnet to hold the loose end of the chain to the sprocket.  Some day someone will get smart and start to put a magnet on the end of the chain on chain whips to serve that purpose.  (If nobody patented it yet, I am hereby documenting my brilliant invention.)

***

Disassemble it?  I assume you mean threaded one, I think not.  If you are talking about a splinned one, I assume they are sold disassembled.

I think Dan has custom milled some chainring teeth or something like that to restore the shape of the worn teeth, I however do not have a milling machine.

A good welder might be able to weld on a new sprocket if they had one, but that would require a lot of careful tolerances to make sure that the body and sprocket are alighned correctly and the sprocket is concentric with the body.  I have a small AC welder, but I am not capable of that.

For a long trip to the middle of nowhere, I think the splinned carrier would be the best idea, perhaps a spare sprocket and spare circlip.  Plus of course the Rohloff tool, in the event that the hub internals need to be accessed.

Danneaux

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Re: Rohloff sprocket wear
« Reply #10 on: February 20, 2019, 08:19:54 PM »
Quote
I think Dan has custom milled some chainring teeth or something like that to restore the shape of the worn teeth, I however do not have a milling machine.
I have indeed custom-milled the teeth on vintage freewheel cogs to keep them going. I have a stash of old SunTour Pro-Compe and Ultra freewheel bodies and cogs plus a few Regina Oros for my older bikes. So long as the tooth profiles can be restored and then re-hardened and quenched, all is good and their lives can be extended for some time. I also make my own Regina pawl springs from "music" wire when the originals wear out. I've also recycled the door springs on old floppy diskettes to use as pawl springs for other brands.

A couple years ago, I was faced with removing a very worn Rohloff cog for a friend. The teeth were just spikes and a chain whip couldn't really engage so I made a specialized pin wrench to do the job. All it required was some 5mm sheet steel which I milled into a sort of Y shape with rounded jaws and a handle. I then drilled holes and threaded in some cap-head allen screws. The heads engaged the holes in the cog and it spun off nicely, opposed by the Rohloff remover. I wish I'd kept it or taken a photo, but it was recycled into the next workshop project.
Quote
Speaking of whips, something I started to do a few years ago - when you are working with a chain whip, the end of the chain often falls from the sprocket and is quite inconvenient.  I bought some tiny little very strong magnets.  I use a small magnet to hold the loose end of the chain to the sprocket.  Some day someone will get smart and start to put a magnet on the end of the chain on chain whips to serve that purpose.  (If nobody patented it yet, I am hereby documenting my brilliant invention.)
I've long used a small cable tie for the same purpose, to keep the chain from disengaging under pressure if the loose end falls free. It also ensures as full engagement as possible. I just snip it once the cog/sprocket is off.

Best,

Dan.

mickeg

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Re: Rohloff sprocket wear
« Reply #11 on: February 20, 2019, 10:21:59 PM »
... A couple years ago, I was faced with removing a very worn Rohloff cog for a friend. The teeth were just spikes and a chain whip couldn't really engage so I made a specialized pin wrench to do the job. All it required was some 5mm sheet steel which I milled into a sort of Y shape with rounded jaws and a handle. I then drilled holes and threaded in some cap-head allen screws. The heads engaged the holes in the cog and it spun off nicely, opposed by the Rohloff remover. ...

That is a brilliant idea. 

Andre Jute

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Re: Rohloff sprocket wear
« Reply #12 on: February 21, 2019, 12:37:03 AM »
Brilliant, Dan.

Danneaux

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Re: Rohloff sprocket wear
« Reply #13 on: February 21, 2019, 01:22:20 AM »
Although I failed to keep my Danneauxmade Rohloff cog removal tool, it was modeled broadly after a Sugino BB pin wrench, shown in photos 1 and 2 below, but scaled up and dimensioned to fit the Rohloff's sprocket holes. I used four allens to ensure good engagement and spread the forces more evenly if the sprocket had been stuck. The pictures should give a good idea of the concept.

I've also included photos of a couple more of my homemade tools, some of many. One is a "lightweight" touring chain whip made of aluminum bar stock I made 41 years ago, likely similar to the one Julien has. I have a very stout steel version made by SunTour for home shop use. The other tool pictured below is a headset wrench made of steel I tempered and sized to fit a Tange Falcon threaded adjustable headset race and lock nut. Not the prettiest tools, but fully functional and cheap as materials and a bit of labor. I offset the handle to get it out of the way of the locknut wrench. I've made adjustable pin wrenches and hooked lockring spanners and lots of brake-related tools as well when what I wanted/needed was either unavailable, too long a wait or too expensive to buy for a single use or application.

Best,

Dan.
« Last Edit: February 21, 2019, 02:07:37 AM by Danneaux »

mickeg

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Re: Rohloff sprocket wear
« Reply #14 on: February 21, 2019, 04:30:38 AM »
Instead of milling the one time use Rohloff sprocket wrench from a sheet, I probably would have used two pieces of bar stock, hinged with a bolt to make the Rohloff specific pin wrench, the only reason being that is stuff I have on hand and could accomplish with a hack saw.  And it would also fit different sprocket sizes as long as I was lazy and only used two 5mm bolt heads to fit the Rohloff sprocket, not four bolts.  But I must say I am impressed.