Trim Front mech ?

MB Lacey

Hi all

My new bike has a 105 5800 groupset.
I've just read a review which says

'The only issue I found was trying to trim the front mech. This requires the tiniest of touches on the lever to get right and nine times out of ten you're just going to end up shifting to the small ring'.

What does this mean please?
Does it mean cycling up a sharp, sudden hill, needing to quickly change to an easier gear but gears are ballsing up and not responding to emergency situation, so instead of finding an easier gear the bike goes into a harder gear resulting in lots of swearing and falling over because you're still clipped in going up a steep hill?

Or because they're trying to trim the fd are they talking about the small ring at the front and not the smaller ring on the cassette?
Why would you be trimming a fd? Is that just the slight movement of the shifter you make to sometimes shift the gear up when it hasn't shifted properly?


Full road cc review here

TooObvious

So, the great thing about the old down-tube shifter was that you could move the front derailleur effectively any amount you liked within it's range of movement. If you were in a situation whereby you inexplicably (!) had the chain in the big ring at the front and the big ring at the back, this could create chain rub on the derailleur, with the downtube shifter you could move it slightly to reduce or resolve the rubbing. The advent of indexed shifting makes this more difficult - Sram users, I believe are able to trim their front derailleurs.

smacl

TooObvious wrote: »

Sram users, I believe are able to trim their front derailleurs.

AFAIK trimming is available on many front mech shifters, certainly the case on my Veloce triple in that you have two clicks per chain ring, one to shift and one to trim. Pretty sure the same is true of my Ultegra double.

MB Lacey

Thanks both, but still unclear on original quote from review - do you recognise what scenario the reviewer is talking about?

magicbastarder

what i assume they mean is that a half-push on the shifter should produce a half-shift, and a large push should produce a full shift - but for them, and sort of use of the shifter is producing a full shift.

smacl

MB Lacey wrote: »

Thanks both, but still unclear on original quote from review - do you recognise what scenario the reviewer is talking about?

You've put the chain into the big ring and smallest cog on the cassette, pushing the outer lever as far as it will go. As you move through the cassette to easier gears you start to get some chain rub, so you'd like to trim, i.e. move the front mech to stop the rubbing while remaining in the big ring. According to the reviewer, 9 times out of 10 this doesn't work and you end up in the small ring instead.

MB Lacey

magicbastarder wrote: »

what i assume they mean is that a half-push on the shifter should produce a half-shift, and a large push should produce a full shift - but for them, and sort of use of the shifter is producing a full shift.

Well that's not very good, I'm surprised these shifters are getting such good reviews.
Good shifters should result in getting the gear you want immediately without messing around with half shifting and maybe it working and maybe it not working etc

cython

I think the point that they are making is that when you have shifted "all the way up" at the front, then there are two clicks available in a single stroke to you on the small lever, one of which trims by letting the derailleur move a little left, the other drops you to the small ring. I think the reviewer is suggesting that you'll more often go through the first click, and hit the second when trying to trim on the big ring. It hasn't been my experience, for what it's worth, and the first click is easy to hit without shifting all the way down.

07Lapierre

MB Lacey wrote: »

Thanks both, but still unclear on original quote from review - do you recognise what scenario the reviewer is talking about?

trimming stops the chain rubbing/rattling against the FD when the chain is on the Large chainring.

example: your cycing with the chain on the small chainring and you shift up onto the big chainring. If the chain is on the larger sprockets on the rear, the chain will rub the FD and make a rattling sound. if you push (gently) the small left shifter lever, the FD will move slightly to the left (it wont shift the chain back onto the small chainring).

On some shimano levers it doesn't work to well in that its hard to push the lever gently enough! push too gently and it doesn't work..push too hard and it shifts the chain onto the small chainring. it takes practice to get it right. (or just upgrade to Ultegra or Dura ace! )

neris

Was watching a gcn video few weeks back when changing my front Derailleur and the guy on video said shimano have a movement in the front derailleur to stop the chain rubbing off it. It's not a click just a bit of movement

MB Lacey

Thanks all, I think I get it now.
My commuter has the old ultegra 6600 which works flawlessly without any half shifting or gentle persuasion to stop the chain from rubbing on the fd.
I wonder why Shimano feel the need to put the trimming feature on 105 but not on ultegra / dura ace?

Cee-Jay-Cee

MB Lacey wrote: »

Hi all
'The only issue I found was trying to trim the front mech. This requires the tiniest of touches on the lever to get right and nine times out of ten you're just going to end up shifting to the small ring'.

Who ever wrote that review hasn't got their FD set up correctly. I would say I'd over-trim once every 100 times or possibly less.

Cee-Jay-Cee

MB Lacey wrote: »

Thanks all, I think I get it now.
My commuter has the old ultegra 6600 which works flawlessly without any half shifting or gentle persuasion to stop the chain from rubbing on the fd.
I wonder why Shimano feel the need to put the trimming feature on 105 but not on ultegra / dura ace?

It's a feature on both Ultegra and Dura-Ace and the new Tiagra too.

It's also on my Tiagra 4600 but only on the small ring.

MojoMaker

You're gonna notice this much more on 11s groups obviously. FD rub was almost non-existent on the older ultegra 10s groups.

crosstownk

07Lapierre wrote: »

trimming stops the chain rubbing/rattling against the FD when the chain is on the Large chainring.

example: your cycing with the chain on the small chainring and you shift up onto the big chainring. If the chain is on the larger sprockets on the rear, the chain will rub the FD and make a rattling sound. if you push (gently) the small left shifter lever, the FD will move slightly to the left (it wont shift the chain back onto the small chainring).

^^ This sums it up.

Think of it as four shift positions for the front mech - two for each chain ring.