Author Topic: sprocket reversing problem anyone?  (Read 25965 times)

redcogs

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sprocket reversing problem anyone?
« on: August 16, 2006, 04:35:16 PM »
my sprocket needs reversing, because of wear (it has a 'wave' type appearance).  So, i purchased the said special tool, which fits a treat.

Problem is that freeing the sprocket seems to require a great deal of force - more than i have been prepared to apply so far - i'm a bit worried about damaging any of the hubgear internals...  the 'chainwhip' that i'm using seems to be straining to near its breaking point (it is also new) so i have given up (so far).

Question is, has anyone else experienced this prob?  Any tips?  Should i use a hammer on the cog?

i'm a bit miffed at my inability to perform what seems to be a simple operation.[:(]
 

stutho

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Re: sprocket reversing problem anyone?
« Reply #1 on: August 17, 2006, 07:51:49 AM »
I along with others have had problems removing the sprocket.  Even if the sprocket is copper greased it still need a VERY large amount of torque to remove it.  I snapped the pin on my first chain whip removing a copper greased sprocket.  After buying a better and LONGER chain whip I got it off.  

Before you start muscling away don't forget to do a reality check.

  • Is the chain whip fully engaged

  • Is the chain whip turning in the correct direction (Anticlockwise)

  • Can the 'special tool' slip? (Make sure the Quick release / axle bolts are holding the 'tool' firmly in place.)

  • Is the shifting spanner fully engaged and tight on the 'tool' and is the spanner the correct way up

  • **IMPORTANRT** when the Sprocket finally comes free am I going to hurt my hands when the spanner meets the chain whip

  • Check again that the chain whip is turning anticlockwise and the 'tool' clockwise - it is easy to get this wrong!


If you are in any doubt about the quality of you chain whip I would replace it with a nice BIG one - If I had of done this I wouldn't of marked the hub when my first tool broke.

When you eventually do get the sprocket off remember to copper grease the threads before putting it back on.

Incidentally how many miles did you get from side 1 of the sprocket?

AndyB

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Re: sprocket reversing problem anyone?
« Reply #2 on: August 17, 2006, 08:25:27 AM »
Hi Redcogs,
Don't worry, it should be simple to remove the sprocket(with the correct tools), I'll try and talk you through it...please accept my apologies in advance, if the first part is not applicable to you but I have presumed that this information may also be of interest to others too!

It is best if you rehearse all the operations in your head, before "going for it!"

The first thing to realise is that, if you have ever used a cassette remover and chain whip to remove a cassette, you will be tightening up the sprocket on the Rohloff hub, if you attempt to use the chain whip in the same direction as you would with a cassette hub. If you have done this and used enough force to almost snap the chain whip, then you now have the sprocket on really, really tight!

The reversal of the sprocket should be planned, in advance of needing to do it...given the massive service life of the sprocket, the need to reverse it, shouldn't be a thing that takes you by surprise. I say this because you will require access to a large vice, which is mounted securely to a workbench.

Remove the QR skewer, locate the sprocket removal tool's lugs into the slots on the hub and replace the QR skewer...this is important to maintain secure location. Tighten the QR fully and then back it off a quarter of a turn.

Now locate the flats of the tool in the jaws of the vice and clamp the tool securely.

Take the chain whip and wrap it carefully around the sprocket and use its leverage to turn the sprocket ANTI CLOCKWISE.(when viewed from the sprocket towards the hub)This may take considerable force.

NOTE THAT BECAUSE THE HUB IS INVERTED (SPROCKET SIDE DOWN)THIS WILL MEAN LEVERING THE CHAIN WHIP CLOCKWISE, AS YOU SEE IT, WHEN LOOKING FROM ABOVE...once the sprocket moves, remember that you have the QR skewer locking the tool on and remove it (that's why I said you must back it off a quarter of a turn.)

I hope that this is clear...if it is not, please re-read what I've written and if it still does not make sense...please contact me.

All the best,
Andy B. (Thorn's designer)




quote:
Originally posted by redcogs

my sprocket needs reversing, because of wear (it has a 'wave' type appearance).  So, i purchased the said special tool, which fits a treat.

Problem is that freeing the sprocket seems to require a great deal of force - more than i have been prepared to apply so far - i'm a bit worried about damaging any of the hubgear internals...  the 'chainwhip' that i'm using seems to be straining to near its breaking point (it is also new) so i have given up (so far).

Question is, has anyone else experienced this prob?  Any tips?  Should i use a hammer on the cog?

i'm a bit miffed at my inability to perform what seems to be a simple operation.[:(]

 

stutho

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Re: sprocket reversing problem anyone?
« Reply #3 on: August 17, 2006, 08:41:13 AM »
Andy,
quote:
remember that you have the QR skewer locking the tool on and remove it (that's why I said you must back it off a quarter of a turn.)



Unless the design of the tool has changed, this info may not be correct.  With my Rohloff tool it can be left attached to the wheel through all stages of removing the sprocket (i.e. the sprocket fits over the tool.

See page 90 of the sevice handbook
« Last Edit: August 17, 2006, 08:47:46 AM by stutho »

redcogs

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Re: sprocket reversing problem anyone?
« Reply #4 on: August 17, 2006, 08:50:06 AM »
Thanks for the advice/help AndyB, i'll let people know when i've completed the task.  

Sorry Stutho, i can't answer accurately the question about miles achieved on the cog - i got my Rohloff pre owned from Germany.  However, i can say that at least 6000 (faultless) miles have been clocked since ownership came to me.  [:)]  Rohloffs are great.
 

AndyB

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Re: sprocket reversing problem anyone?
« Reply #5 on: August 17, 2006, 10:53:43 AM »
Hi Stutho, you are quite correct...Rohloff have made the tool so that the sprocket will pass over it...feeling a bit silly, Andy B.

quote:
Originally posted by stutho

Andy,
quote:
remember that you have the QR skewer locking the tool on and remove it (that's why I said you must back it off a quarter of a turn.)



Unless the design of the tool has changed, this info may not be correct.  With my Rohloff tool it can be left attached to the wheel through all stages of removing the sprocket (i.e. the sprocket fits over the tool.

See page 90 of the sevice handbook

 

graham

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Re: sprocket reversing problem anyone?
« Reply #6 on: August 20, 2006, 05:02:10 PM »
After I bent my cheapo chain whip trying to do mine for the first time, I gave up and took the wheel, tool and photocopy of the instructions to my local bike shop on the assumption they'd have a decent chain whip. The nice man there did it in less than 5 minutes and charged me two quid. A lot less than buying a decent chain whip.
The second one I did, I managed using my own chain whip. But I now know I've got backup if I need it.
 

redcogs

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Re: sprocket reversing problem anyone?
« Reply #7 on: September 06, 2006, 08:18:21 PM »
Hi.  Reversed the sprocket myself yesterday using the benchvice method recommended by AndyB.  An easy job in the event.  Doing the job seems to have made a difference to gearchanging as well, it all feels a bit more 'crisp', not that it felt loose previously.. its just that, whenever i perform maintainance, even that which involves fairly small scale adjustments, i tend to feel that the cycling experience is enhanced thereafter.

Probably all in the mind.

regards all. [:)]
 

daviddd55

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Re: sprocket reversing problem anyone?
« Reply #8 on: April 20, 2007, 10:07:11 PM »
being a novice with Rohloffs, I'm wondering if the chain whip is the same as the deralleur one?

stutho

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Re: sprocket reversing problem anyone?
« Reply #9 on: April 21, 2007, 08:58:46 PM »
Yes it is but you will need a quality tool - I broke my first one

daviddd55

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Re: sprocket reversing problem anyone?
« Reply #10 on: December 11, 2007, 12:37:23 AM »
...am i right in thinking that by taking the wheel to any decent  bikeshop I won't need any 'special tools'? Or is there a specific Rohloff / Thorn tool required?

PeLu

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Re: sprocket reversing problem anyone?
« Reply #11 on: December 11, 2007, 03:35:15 PM »
Or is there a specific Rohloff / Thorn tool required?
It is the Rohloff tool fro removing the sprocket. This is a Rohloff special.
 

daviddd55

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Re: sprocket reversing problem anyone?
« Reply #12 on: January 11, 2008, 02:46:15 AM »
update - I took the bike to St Kilda Cycles in Melbourne and got the sprockets and chain replaced (6000km) - with a new chain the rear sprocket was jumping (it wasn't ever turned around). The guy there broike a whip and almost did his back in by the sound of the cursing. Cost me $199 (80 QUID) but glad it's done now. I may need to do this all over again as I have another 14000 km (god knows where ?!) to go yet around Oz. I arrived in Canberra yesterday - nice place.

freddered

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Re: sprocket reversing problem anyone?
« Reply #13 on: February 01, 2008, 11:33:53 AM »
Quote
The nice man there did it in less than 5 minutes and charged me two quid.

Quote
The guy there broke a whip and almost did his back in by the sound of the cursing. Cost me $199 (80 QUID)

80 !!! Did I miss something?  Did he throw in a new wheel or something?  That's the same cost as a new sprocket, removal tool, new chainwhip, new vice and a few beers to celebrate completing the task
 

freddered

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Re: sprocket reversing problem anyone?
« Reply #14 on: February 04, 2008, 12:56:09 PM »
If the sprocket spins off anti-clockwise, what stops it from spinning off under load from the pedals?