Front Derailleur Dropping over bumps?

[Ginge_126]

I think its a mis-assembled bar end lever.
The lever needs to be assembled so the downshift (roughly 90 degrees of movement from horizontal to vertical) has a lot of resistance in the lever: because that shift is "helped" by the mech. return spring.
The lever upshift (from vertical to horizontal) doesn't need much lever resistance.
The difference is in how the shiny ferrule thing seats on the ali. lever body; the lever body has a square pattern, and its critical which orientation you fit the shiny ferrule bit.
unfortunately, its been a lot of years, and I can't remember exactly!
AH! heres some pictures I took in 2015!....unfortunately at that time I knew what I was doing, and there are no captions!

002 by 531colin, on Flickr

Thats the ali. lever body and the back of the shiny ferrule

014 by 531colin, on Flickr

Thats the ferrule assembled onto the lever body; note the orientation.
Now I'm guessing thats the correct orientation, unless I was being really obtuse all those years ago. Its probably on here somewhere, if you want to search!

Found it viewtopic.php?p=888686&hilit=bar+end+lever#p888686

EDIT.....insufficient friction in the lever + return spring + bump in the road = lever slips....if its not obvious!

I'm going to take mine apart and check it all tomorrow, replacing with new cabling and outers. See how I get on then. Thanks very much for this, none of my books cover bar end shifters.

[Steve O'C]

You seem to have 2 problems. High resistance when you shift up but not enough resistance to prevent ghost shifts down when you hit a bump. I had this problem when I routed the cable the wrong way at the mech, it needs to go outside of the metal tab at the pinch bolt as shown below. Routing it inside of the tab makes upshifts hard which I tried to compensate for by reducing the tension in the screw at the bar end giving me exactly the same problem you have.

Untitled.jpg (18.46 KiB) Viewed 336 times

[531colin]

I still don't think its the cable, because worn cable gives you more friction......your set-up is ghost shifting because there isn't enough friction to hold against the F. mech. spring.

I would spend 5 minutes re-assembling your front bar end lever, and while you are at it check the cable fixing on the F. mech. as suggested above.......I don't think its that, because wrong cable routing would give a "stiff" change up to the big ring....which you have(?)....in the case of wrong cable routing, the upshift is stiff because you have less mechanical advantage.......I can't see it giving ghost shifting, but its a 30 second check so its worth looking.

Replacing cable outer means un-taping the bars and re-taping them, which is a pain and i don't think you need to do it!

[531colin]

............. I tried to compensate for by reducing the tension in the screw at the bar end giving me exactly the same problem you have.

Amazing what I found when I read it properly!
My 9 speed (left) bar end lever doesn't have a tension screw; its a very fine ratchet....
every days a school day!

[Ginge_126]

You seem to have 2 problems. High resistance when you shift up but not enough resistance to prevent ghost shifts down when you hit a bump. I had this problem when I routed the cable the wrong way at the mech, it needs to go outside of the metal tab at the pinch bolt as shown below. Routing it inside of the tab makes upshifts hard which I tried to compensate for by reducing the tension in the screw at the bar end giving me exactly the same problem you have.

Untitled.jpg

I've had the cable out, and it was even difficult to pull through the outer, so that's in the bin.

And yes when I'd changed the front derailleur I'd fitted the cable inside the tab. That'll be rectified when I replace the cable. Cheers for the heads up. Every day's a school day

[Ginge_126]

I still don't think its the cable, because worn cable gives you more friction......your set-up is ghost shifting because there isn't enough friction to hold against the F. mech. spring.

I would spend 5 minutes re-assembling your front bar end lever, and while you are at it check the cable fixing on the F. mech. as suggested above.......I don't think its that, because wrong cable routing would give a "stiff" change up to the big ring....which you have(?)....in the case of wrong cable routing, the upshift is stiff because you have less mechanical advantage.......I can't see it giving ghost shifting, but its a 30 second check so its worth looking.

Replacing cable outer means un-taping the bars and re-taping them, which is a pain and i don't think you need to do it!

I have (had) a stiff change to the big ring...it was nigh on impossible to pull the lever up. I've taken the outer away now (I had recently fitted the outer housing plastic guide so I can slide a new one back.

Have got the shifter disassembled now. It seemed to have been assembled correctly with the indentation on the cover seated downwards.
I was expecting more moving parts but the lever doesn't come apart (I was expecting delicate washers and springs to leap out over the floor).

I'll do all the suggestions over the next day or so and write up how it went. Thanks.

[Ginge_126]

Thank you all for your valued input, a combination of many has sorted it.

It wasn't the cable, but the clamped end was U/S after repeated clamp/unclamping, so that was replaced. I'd fitted new bar tape and used some outer cable guide, so I could just remove without removing tape.

Outer cable replaced as that was seriously sticky/rusty.

Disassembled the left lever, checked and re assembled as per 531Colin's guide. Put it all together and it works fine. There is a fine ratchet now whereas before there was none. The action is far lighter and the lever moves from 6-9 o'clock , it was closer to 7-10 before.

Also clamped the cable the correct way around the tab!

Top job, I'm happy now!

[531colin]

Good job!