Revoshift SIS repair

[Vinay Rao]

Hi

My cycle has a 7-speed Shimano Revoshift SIS i.e. Twist + Index shifter. For the past few weeks it had become increasingly difficult to downshift to a larger rear sprocket. About a week ago, it more or less gave up the ghost. It takes an inordinate amount of effort to move it from '7' and it 'slips' to '3' and no further, but the chain derails to the '5th' sprocket at most, and not the '3rd' as the shifter would have me believe. It 'slips' back to '7' with ease though. I can no longer feel the 'indexing'

Actually I cannot remember if the shifter ever indexed smoothly and easily. I've been riding just this ONE cycle for the better part of 3 years - without the benefit of comparison - and the chain always jerked my pedaling as it downshifted along the rear sprockets. I ride about 10 times a month to work and back, about 40km to + fro. I've reconciled to not shifting too much but even a little sprocket shifting majorly helps tackle Bangalore's slopes and traffic.

The shifting mechanism - Arm and Cage - seem to work alright when I push by hand, so I'm not looking to fix something that isnt broken there. Comes down to the shifter and the wire. I'm not sure if the wire is chafed and the revoshift isnt working as a result. The lack of 'indexing' makes me want to take the twist shifter apart to see if I can fix it.

Has anyone done this before? Anything to look out for that might be causing the problem? I'm going with the presumption that I cant do much worse than it already is. I looked at these two spots on the webs, but did not learn enough
http://www.parktool.com/blog/repair-help/shift-levers-shifters
http://techdocs.shimano.com/techdocs/index.jsp

Any pointers are much appreciated.

Vinay Rao

PS: Any pointers to better shifters (are trigger shifters better? which ones?) would be great too, and to bodies that can do a good job in retrofitting them in.

On Fri, Jan 29, 2010 at 2:48 PM, abhishekmadan <abma...@gmail.com> wrote:

If it's a revoshift it could be that SIS thing, which is lower than
Tourney and pretty bad.

On Jan 29, 2:06 pm, Ajay Bharadwaj <bharadwaj.a...@gmail.com> wrote:
> Hi,
>
> I am an owner of a Hercules ACT 110. I happened to see the cousin of
> 110 aka 110s. The 110s is a cool 3k cheaper ( comparing MRP of both)
> than the 110. On close inspection i found the following differences.
>
> Frame:                          Aluminum alloy vs Steel
> Rear Derailleur :             Shimano Tourney vs ( Just Shimano was
> written on it, no idea if its a lower variant or not. Does Shimano
> make something cheaper than Tourney??  )
> Front Derailleur:             Shimano 050 vs ( Something that looked
> different.
> Handle bar stem:           ACT110 has something which can be raised.
> ( Promax similar to present in Trek
> hybrid ).                                 110S has fixed system where
> handle bar cannot be raised.
> Shifters:                      Trigger shifters for 110 and revo
> shifters for 110S
> Tires and rim                Same

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[Sunil Raghavan]

Root cause isn't obvious reading your post - it could be the cable giving way or some shifter issue - best to take it to a good bike shop and have it fixed. They'll hopefully also have replacement parts for whatever is broken.

[Shree Kumar]

Hi Vinay,

Not sure if I understood the problem right. Can you remove the rear wheel and test just the shifter ? Checking the operation of the shifter is much easier in this scenario.  Just twist the shift end-to-end, and check if the cable slack changes.

I had the same on my Hero Thunder I think - and an earlier cycle as well. Can't remember it needing much repair - but it was oiled from time to time. I suspect your problem may be related to the deraileur.

If you are dropping by Innominds some time, then I'll have a look.

HTH
-- Shree
http://www.shreekumar.in/

http://www.shreekumar.in/

[Sreepathi Pai]

If you've never ever changed the shifter cables, you're possibly
looking at very rusted cables. Nothing to do with the twist shifter.

It costs 15 bucks (wire only) or so, and is easy to replace. You may
have to replace the outer covering as well.

Note that if you delay changing the wire, the friction may break small
parts in your shifter.

--
Sreepathi Pai

[Vinay Rao]

The derailleur (local rear wheel sprockets shifting) works fine by itself. I can test this without having to take off the rear wheel. As I suspected too the shifter cable might be too stiff. It seems to want to drag back the twist shifter to '7' position which I guess is its position of least resistance.

Good chance that those small parts in the shifter are already broken, which is why I don't feel the indexing. I stopped by at some random cycle store and the chap said it will cost Rs.450 to replace the shifter, but did not feel confident about his diagnosis or the originality of the component. Does an original Shimano 7-speed shifter come at this price?

Best,
Vinay

[Sreepathi Pai]

On Tue, Oct 9, 2012 at 5:01 PM, Vinay Rao <vina...@gmail.com> wrote:
> Good chance that those small parts in the shifter are already broken, which
> is why I don't feel the indexing. I stopped by at some random cycle store
> and the chap said it will cost Rs.450 to replace the shifter, but did not
> feel confident about his diagnosis or the originality of the component. Does
> an original Shimano 7-speed shifter come at this price?

You may want to check out if the Decathlon store has replacements for
your shifter. I got SRAM MAX which are way more comfortable for me.
They were on sale at that time, around 200--300 for both L and R.

Don't know about pricing for the original Shimano shifter.

--
Sreepathi Pai