SL-BS78 Shifters PROBLEM

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pickerd
Posts: 104
Joined: 22 Mar 2015, 7:01pm

SL-BS78 Shifters PROBLEM

Postby pickerd » 9 Dec 2015, 8:35pm

I'm trying to get these shifters working on my touring bike.
I have tried both a 105 RD 10 speed and a M591 RD 9 speed rear derailleur with no luck.
I'm pretty sure these are supposed to be 10 speed shifters and it says so on them.
The problem seems to be that they shift slightly more than one cog for each index.
I've tried two shifters now with no luck.
Interestingly I did a conversion to bar ends with SL-BS79 shifters and they worked fine.
Any ideas? ??

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recordacefromnew
Posts: 333
Joined: 21 Dec 2012, 3:17pm

Re: SL-BS78 Shifters PROBLEM

Postby recordacefromnew » 10 Dec 2015, 12:17am

Have you tried to isolate the issue by measuring the cable pulled per click, and compare it with the figure at http://www.ctc.org.uk/cyclists-library/components/transmission-gears/derailleur-gears/shimergo?

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: SL-BS78 Shifters PROBLEM

Postby Brucey » 10 Dec 2015, 12:50am

stupid thoughts;

1) is there any chance you have mounted the cable the wrong side of the pinch bolt in the rear mech?

2) SL-BS78 is meant to have a friction mode; sometimes the shifter will behave oddly if the mode control isn't fully home.

SL-BS79 is meant to be the same as SL-BS78 but has no friction mode. All shimano/dura ace road 10s ought to work together.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

pickerd1
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Joined: 31 Mar 2014, 5:05pm

Re: SL-BS78 Shifters PROBLEM

Postby pickerd1 » 10 Dec 2015, 8:01am

Thanks very much for your replies.
I will try a few things tonight including:
- measure cable pull
- check cable mounting
- 'hubbub' style cable mounting - reducing the pull ratio slightly may help
- strip and service the shifter - is there anything inside that can impact shifting?
- check the cassette cog spacing (pretty sure is stock and still riveted)
Another point to note is that the shifters are second hand and may be worn.
I will revert to friction mode if all fails until I can get hold of a set of NEW SL-BS79 bar ends.

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iow
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Joined: 27 Jul 2010, 11:01am
Location: isle of wight

Re: SL-BS78 Shifters PROBLEM

Postby iow » 10 Dec 2015, 8:39am

if they're anything like the 9 speed shimano barends it's easy to unknowingly assemble them incorrectly - if the lever has enough throw to touch it's mounting it's assembled incorrectly - if they are assemble correctly the built-in internal stop will not allow this..
mark

pickerd
Posts: 104
Joined: 22 Mar 2015, 7:01pm

Re: SL-BS78 Shifters PROBLEM

Postby pickerd » 11 Dec 2015, 11:35am

A bit of feedback....
Stripped it backhand rebuilt paying close attention to shifter assembly and cable mounting at the rear mech. Problem still there.
Checked spacing between cogs on cassette and found the gap between 3 and the 1/2 carrier was a little small.
Fitted a shim to increase gap and shifting now works!!!!