Cycling UK Forum

Posted: **12 Jun 2023, 6:53pm**

Hi all,

I've tried a search using different terms but nothing specific to my problem and I'm sure someone will know straight away.

I've got an early 2000's Dawes Horizon and am having issues with the front derailleur moving very slightly to a smaller chainring when I hit a bump. I can move the shifter again and it's fine until the next time.

I have a 110mm bottom bracket, 28/38/48 Spa TD2 Chainset (spa recommend 110mm) with a Shimano Sora Triple front mech. (The derailleur is a bit newer than the bike but from another bike, I fitted it).
I've checked the distance between cage and large chainring and is according to Shimano's guide. The cable is new and has had PTFE sprayed.
Shifter is Shimano Dura Ace Bar end, which feels tight/difficult when shifting to larger chainring.

The entire drivetrain was working together on my Ridgeback World Voyage without issue (excluding bar end shifter) I've just transferred it over to this bike.

Am I missing something really obvious?

Cheers in advance for any help.

Posted: **12 Jun 2023, 7:06pm**

I'd check for stiction somewhere in the entire changing mechanism. That could explain both the tight shifting as you go up and the movement caused by shock from the road.

Jonathan

Posted: **12 Jun 2023, 7:25pm**

+1 for sticktion.Replace inner and outer.

Posted: **12 Jun 2023, 8:12pm**

Cheers, it does feel sticky, but I thought it shouldn't be after spraying. I haven't changed the cable outer though. Will give that a go first.

Posted: **12 Jun 2023, 8:55pm**

Ginge_126 wrote: ↑12 Jun 2023, 8:12pm Cheers, it does feel sticky, but I thought it shouldn't be after spraying. I haven't changed the cable outer though. Will give that a go first.

Spraying a sticking, rusty cable will not help free it. The corrosion causes the cable to expand and lube might react with the cable liner making it swell. Either or both reduces the gap that allows free movement of the inner.
Replacement is the only reliable solution .

Posted: **12 Jun 2023, 9:10pm**

Just a couple of questions- how many miles has the front derailleur done, and is the gear shifter friction or indexed?

Posted: **12 Jun 2023, 9:28pm**

cycle tramp wrote: ↑12 Jun 2023, 9:10pm Just a couple of questions- how many miles has the front derailleur done, and is the gear shifter friction or indexed?

The front derailleur is not new and has toured (laden) around Europe with the previous owner on the donor bike. I have wondered if it's worn out...

Posted: **12 Jun 2023, 9:29pm**

cycle tramp wrote: ↑12 Jun 2023, 9:10pm Just a couple of questions- how many miles has the front derailleur done, and is the gear shifter friction or indexed?

The cable is new, the outer isn't. Will tackle both though and go from there.

Posted: **12 Jun 2023, 10:23pm**

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!

Posted: **12 Jun 2023, 10:43pm**

It sounds like the same problem djnotts had in the thread - viewtopic.php?t=140196. He explained the cause and how he fixed it on the first page of the thread. Edit - the same as 531colin's explanation above(?).

Posted: **12 Jun 2023, 10:44pm**

Ginge_126 wrote: ↑12 Jun 2023, 9:28pm
cycle tramp wrote: ↑12 Jun 2023, 9:10pm Just a couple of questions- how many miles has the front derailleur done, and is the gear shifter friction or indexed?
The front derailleur is not new and has toured (laden) around Europe with the previous owner on the donor bike. I have wondered if it's worn out...

I think you'd be right to look at a new cable, and then as 531Colin suggested looking at the shifter, if after all that, it's still ghost shifting following a bump, then perhaps there is a situation where there may be enough play at certain points in the pivots of the derailleur to allow it you happen.

Posted: **13 Jun 2023, 8:26am**

Its not the bloody cable!
A knackered cable will give TOO MUCH FRICTION.
The OPs F. mech. ghost shifts going over a bump BECAUSE THERE ISN'T ENOUGH FRICTION TO HOLD THE MECH. IN PLACE AGAINST THE SPRING.

In any case, I would spend 5 minutes checking the lever assembly BEFORE getting involved in un-taping and re-taping the bars.

Posted: **13 Jun 2023, 8:38am**

I don't remember that 2020 thread at all....but it points out a couple of things.....
I have only ever used 9sp bar end levers, and that only briefly. There are differences between levers depending on date of manufacture and how many speeds.
Also, between the 2 old threads (I think; I don't have the determination to re-read it all) there are a couple of people who report setting up left bar end levers so they "index" the middle ring position. That is actually a "wrong" set-up; the lever is assembled 90 deg. (?) out of position, so that what should be the "horizontal" detent position (big ring) becomes a middle detent position (middle ring). The Granny ring position is OK but will rest against the lever body rather than the inbuilt lever end stop; the new big ring position is now past the detent so relies on lever friction, whereas correctly assembled there is a fine ratchet on the whole of the upshift movement. ....that friction is not to be relied on to keep the F mech. in position in all circumstances; I think thats exactly why the OPs mech. ghost shifts over a bump.

Posted: **14 Jun 2023, 9:12pm**

531colin wrote: ↑12 Jun 2023, 10:23pm 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!

Ah it might be right...to change to the largest ring I move my lever from vertical to horizontal, so big ring is horizontal and smallest - lever is vertical. Mine sounds like the cable is pulling a**e about face.

I'll have a bit of time tomorrow to have a decent look.

Posted: **14 Jun 2023, 9:15pm**

My resistance is from vertical to horizontal and is extremely difficult despite the limit screws being set right.

Cycling UK Forum

Front Derailleur Dropping over bumps?

Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?

Re: Front Derailleur Dropping over bumps?