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Date: 05 Aug 2007 17:40:38
From:
Subject: May Have Damaged Internals Of Hub Gear With My Tomfoolery
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I have a hub gear system built by Sachs (now SRAM). The manual is
here: http://www.sram24.com/newtechdoc/english/consumers/ghs/pdf/spectro/Ins_sram_S7_8_2005.pdf
(manual differs from my system in that my gears are controlled by a
lever, rather than a twisty thing and in that there is no window in
the shifter housing).
After taking the rear wheel off, to get to the smooth brake-pad
centre, I am unable to get the gears to function again. I accidentally
left the gear in 3 instead of 1 when I took it apart and then switched
to 1 before putting it back together (probably should have left it in
3). Anyway, when the shifter housing is removed from the the shift rod/
tube, the gear lever moves freely between all gears, however when the
housing is replaced onto the shift rod/tube (as in the instructions)
then the gear lever moves either between 1-5 or 1-3 (I get different
results each time I take it off and put it back). It's also more
difficult to move than it used to be. Can anyone suggest how to
resolve or investigate the problem further?
Thanks, Sean
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Date: 08 Aug 2007 13:27:14
From: Chalo
Subject: Re: May Have Damaged Internals Of Hub Gear With My Tomfoolery
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sean.van.der.smy...@googlemail.com wrote:
>
> I have a hub gear system built by Sachs (now SRAM).
...
> After taking the rear wheel off, to get to the smooth brake-pad
> centre, I am unable to get the gears to function again. I accidentally
> left the gear in 3 instead of 1 when I took it apart and then switched
> to 1 before putting it back together (probably should have left it in
> 3). Anyway, when the shifter housing is removed from the the shift rod/
> tube, the gear lever moves freely between all gears, however when the
> housing is replaced onto the shift rod/tube (as in the instructions)
> then the gear lever moves either between 1-5 or 1-3 (I get different
> results each time I take it off and put it back). It's also more
> difficult to move than it used to be. Can anyone suggest how to
> resolve or investigate the problem further?
You didn't damage your hub (the hub always shifts to bottom gear when
the shifting mechanism is removed), you just made some sort of mistake
reassembling the clickbox to the axle. Some small parts may have
become damaged in the process, but all the bits and pieces are easily
available in the event that you actually messed anything up.
A few thoughts:
Sachs hubs are much more robust than their shifters, and failure to
work as intended is usually an indicator of a problem outside, rather
than inside, the hub.
Make sure the red plastic guide is oriented correctly. It's easy to
put it on wrong-end-first, or to fail to get it all the way onto the
groove in the axle end, or to assemble in such a way that its tooth
does not fall into the slot in the end of the shift tube. If the
tooth that aligns the shift tube is all chewed up, you may need to
replace the guide.
If you have to buy a new part, take the opportunity to have the bike
dealer run through the assembly procedure with you at that time, just
in case there's something you are doing in error.
The clickbox that came with my wife's Sachs Pentasport P5 hub was
chronically problematic. It rarely delivered all five gears during
any given ride, regardless what was asked of it. But when I swapped
it for a better quality replacement clickbox and shifter, the hub
worked perfectly-- as it has done ever since. If your shifter and
clickbox have given up the fight, you can replace them with something
that works better.
Chalo
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Date: 08 Aug 2007 08:54:07
From: dvt
Subject: Re: May Have Damaged Internals Of Hub Gear With My Tomfoolery
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sean.van.der.smythe@googlemail.com wrote:
> I have a hub gear system built by Sachs (now SRAM). The manual is
> here: http://www.sram24.com/newtechdoc/english/consumers/ghs/pdf/spectro/Ins_sram_S7_8_2005.pdf
> (manual differs from my system in that my gears are controlled by a
> lever, rather than a twisty thing and in that there is no window in
> the shifter housing).
> After taking the rear wheel off, to get to the smooth brake-pad
> centre, I am unable to get the gears to function again. I accidentally
> left the gear in 3 instead of 1 when I took it apart and then switched
> to 1 before putting it back together (probably should have left it in
> 3). Anyway, when the shifter housing is removed from the the shift rod/
> tube, the gear lever moves freely between all gears, however when the
> housing is replaced onto the shift rod/tube (as in the instructions)
> then the gear lever moves either between 1-5 or 1-3 (I get different
> results each time I take it off and put it back). It's also more
> difficult to move than it used to be. Can anyone suggest how to
> resolve or investigate the problem further?
It's pretty hard to diagnose remotely, but here's a wild guess... How
about your shift rods? The clickbox pushes two shift rods (one inside
the other). If one or both of these is bent in some way, your clickbox
might not be pushing on both rods reliably. It's also possible that the
teeth in the clickbox that push on the shift rods are damaged in some
way. I can imagine the shift rods or the clickbox being damaged if
things weren't aligned and the clickbox was reinstalled with the shifter
in 3rd gear. Damage is unlikely, I think, but possible.
My SRAM 7-speed hub has no brake, so I'm not sure what you mean when you
say you took the rear wheel off "to get to the smooth brake-pad centre."
Maybe that's a clue, but I don't know what it means.
--
Dave
dvt at psu dot edu
Everyone confesses that exertion which brings out all the powers of body
and mind is the best thing for us; but most people do all they can to
get rid of it, and as a general rule nobody does much more than
circumstances drive them to do. -Harriet Beecher Stowe, abolitionist and
novelist (1811-1896)
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