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Shimano front (friction) barcon slipping

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Shimano front (friction) barcon slipping

Old 04-29-17, 01:04 PM
  #1  
Metaluna
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Shimano front (friction) barcon slipping

I was doing a routine check of the shifting on my touring bike after replacing the chain, when I noticed that the front bar end shifter wouldn't hold the chain in the big ring. I could get it to sort of go into gear, but the FD cage would drift back until it was rubbing on the outside of the chain, and the slightest touch on the left shift lever would cause the FD to spring back to the middle ring position. Even in the middle ring it doesn't hold very tightly. I found this old thread that suggested tightening the heck out of the fixing bolt to increase friction, but it barely made a difference.

Furthermore, when I unscrewed the shift cable fixing bolt on the FD (i.e. releasing all tension in the cable), the lever would not stay in the lowest gear position, which is when the lever is pointing down towards the ground. There is some kind of return spring that would keep popping the lever back out to about 45 degrees from the vertical. I don't remember it ever exhibiting this behavior before. Usually the lever just stays where you put it, whether under tension or not.

Is the friction mechanism shot, and is there anything I can do to fix it? I can't find any disassembly instructions for this lever online, and looking at it, I can't figure out if it's even possible to take it apart.
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Old 04-29-17, 08:53 PM
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Have you tried increasing the friction in the lever? You don't say which model Shimano bar-con you have, but if it's a friction shifter there should be an adjustment to increase the friction in the lever. On the L-600 "Fingertip Control" it is the slotted screw on the lever:



Tighten it just enough to hold the lever in place after you shift; too tight and it'll be hard to shift at all.
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Old 04-29-17, 09:35 PM
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I believe the OP is using a counter sprung Shimano bar end from the late 1970s/early 1980s era. AFAIK these weren't commonly serviceable. But trying to drip lube, mild heating and immersing in a thin lube might get oil inside.


I never liked these shift levers as they seemed to have a lot of friction within the lever pivot and shadowed the actual der's movements, lots of lever travel and trimming. I found SunTours to be far easier to work with 9and are completely rebuildable). Your opinion may vary.


The reason that the lever won't stay in the low gear position with the cable loose is that the counter spring is pushing the lever towards the high position. Shimano claims this better counter balances the der's return spring. Again YOMV. Remember these levers were designed for yester year's front ders with their often soft return springs. Using them with today's current stronger return springs (of the der) and no wonder the counter spring seems deficient. Andy
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Old 04-29-17, 10:25 PM
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Sorry, I forgot to specify that they are Shimano SL-BS77 9-speed shifters, approximately 10-12 years old. I've had these on and off a variety of bikes over the years, and just pulled them out of storage for a new build a couple of months ago. There's no friction adjust that I can see.

It almost seems like the spring slipped or rotated inside the lever somehow. With the lever off the bike, when I push it into the highest gear (i.e. big ring) position, the spring pulls it back to the middle (where there's a detent, for some reason). If the spring is there to counteract the FD return spring, it has somehow begun pulling in the wrong direction at the high end.
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Old 04-30-17, 05:08 AM
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Metaluna, I have the same shifters on my distance roadie. Mine have no springs, that I can determine, so the mounting screw provides the friction to hold the lever.
https://si.shimano.com/pdfs/ev/EV-SL-BS77-1664.pdf

My front 9S bar end is ratcheted throughout it's lever travel. My front 8S bar end on my touring bike is smoother with the one detent you describe, which on a downshift pretty much indexes to the middle ring.

Brad
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Old 04-30-17, 06:45 AM
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Originally Posted by bradtx
Metaluna, I have the same shifters on my distance roadie. Mine have no springs, that I can determine, so the mounting screw provides the friction to hold the lever.
https://si.shimano.com/pdfs/ev/EV-SL-BS77-1664.pdf

Yes, I never noticed a spring either until this problem started. It's possible that it's not really a spring, but just some component inside that has broken or jammed and is resisting rotation, causing a springy feeling. I'd try flooding it with WD-40, like people do with failing STI levers, but I suspect that would destroy the friction function, even if it did manage to free any stuck parts. There's a tiny hole on the outboard side of the lever body that mates to the lever boss cover (part #2 in the exploded view). That might provide ingress for an appropriate solvent. I'll see if I can get the tip of an awl in there and wiggle it around. Maybe that will free something up. Other than that this thing seems pretty well sealed and non-rebuildable.

My front 9S bar end is ratcheted throughout it's lever travel. My front 8S bar end on my touring bike is smoother with the one detent you describe, which on a downshift pretty much indexes to the middle ring.

Brad
I read somewhere that Shimano changed the design of the 9S shifter slightly over the past ~10 years, so they may have eliminated the middle click. Could be they don't like to acknowledge the existence of triple cranks in their Dura-Ace branded stuff, or just felt it was getting in the way even for triples, which I would somewhat agree with.

I've also heard the shifters have declined in quality over the years, which makes me reluctant to shell out $95 for another set. Microshifts can be had for about $70 (or $50 if you can do without the switchable friction/index function on the rear).

You can also get individual, friction-only, Sunrace levers for about $30 each, but all the ones I've seen are oriented for the right hand side (fixing screw threads in from the left), so they would look a little goofy on the left bar end. Not sure I care all that much about looks at this point though.
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Old 04-30-17, 07:33 AM
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I have even older downtube/barend front shift lever on one bike, a 105 8-speed SL-1057, and it has no springs or detents. The friction is adjusted strictly by the tightness of the mounting bolt.

I wonder if you left out a washer under the mounting bolt.
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Old 05-02-17, 01:47 PM
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Looking at the exploded diagram that bradtx posted, it looks like I have everything shown in the diagram. There's no washer between the head of the fixing bolt and the lever body, for example. The diagram is pretty accurate from what I can see. You can even see how the central bushing that the fixing bolt goes through is flared out like a star nut on one end. I suppose I could try bending those little tabs up and see if I can get it apart that way.

In the meantime I ordered one of these Sunrace friction levers. They're sold individually so I just got the "left" one.
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