Trimming front derailleur

jd843

Guest
Hi there,

I recently purchased the Trek Lexa. http://www.trekbikes.com/uk/en/bikes/road/endurance_race/lexa/lexa_compact/

The bloke in the shop told me about trimming the front derailleur and I've tried having a bit of a play with it but I'm not sure it's working as it should. The bike has 2 sprockets on the front and I am able to trim the derailleur up with a half-click of the large lever. However, I am not able to use the small lever to trim down, so I'm able to get 3 positions from the front derailleur: as close as possible to the frame (in small sprocket); trimmed right in small sprocket; and as far as possible from the frame (in large sprocket). Should there be a 4th position? i.e. trimmed left while in the large sprocket? The small lever seems a bit... spongy when it's pressed, rather than having a "half-click" like the large lever.

Sorry if that doesn't make as much sense as it should - I'm new to the world of road cycling!
 

adamhearn

Über Member
Yes, that makes sense. I've no experience of Shimano Claris but I would expect (though could be wrong) that if trim is supported in one direction, it should work in the other.Might be a cable tension issue?
 
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J

jd843

Guest
Yes, that makes sense. I've no experience of Shimano Claris but I would expect (though could be wrong) that if trim is supported in one direction, it should work in the other.Might be a cable tension issue?
Thanks for the advice. I don't really think I should be tinkering with stuff as I've no idea what I'm doing - and I only bought it a few days ago so the bike shop should probably fix it!

Is it unusual to be having problems this soon after getting the bike? I've only ridden it briefly; I'm new to clipless pedals so I've only been round a car park to get used to them, not even on a proper ride.
 

adamhearn

Über Member
No reason to not ask the bike shop about the trim action; they're the expects. Hopefully it [the operation] can either be explained or improved/rectified by them. The trim function is a nice to have when you're heading towards cross chaining rather than something that's always in use. That's not to say it has no use and shouldn't work as expected of course.

Try to get used to the shoes/pedals combo by clipping in and out whilst next to something soft to land on. Also, you may want to consider having the clip tension set to the lowest strength so it takes the least amount of effort to unclip. You can then adjust this once you're more adept at their use. Always plan well ahead coming up junctions and soon it'll become second nature. The awkward moments are unplanned/emergency braking where you'll be focusing on survival rather than concentrating on unclipping.
 

andyfraser

Über Member
Location
Bristol
My Sora shifter has 4 positions: 2 positions in the lower range, fully left and trimmed up, and 2 positions in higher range, fully right and trimmed left. The trimmed left position is reached by pushing the inner lever half way. I hope that makes sense.
 

migrantwing

Veteran
My 105 5700 has four positions also, although I believe that there should be only three, according to the Shimano Tech docs.

1) Neutral over the small chainring 2) one minor shift with the large lever that trims the small ring toward the large chainring 3) next shift with large lever shifts to large chainring and then 4) a minor shift with the large lever that shifts the FD outward even more by about 2-3mm.

I can also, when in the large chainring, trim in towards the smaller chainring by clicking the inner lever as @andyfraser mention as should be the correct set-up.

It's all to do with cable tension and, as I have mentioned, I believe my FD positions were incorrect. Once I'd set the cable tension correctly, the positions are the same as yours, @andyfraser.

I know I'm not the only one that has come across this phenomena as there are many posts on the internet relating to trim positions. Bizarre!
 
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andyfraser

Über Member
Location
Bristol
@migrantwing That's a much better explanation than mine. :smile:

Annoyingly I'm going to have to tweak my FD soon. Every so often the chain comes off when changing from big to small ring. It's not the limit screws so may be the alignment. It can wait until I replace the chain and cassette in a week or so. :smile:
 

migrantwing

Veteran
LOL @andyfraser It's not necessarily a better explanation, just that it took a longer amount of time to type it :smile:

I'm not familiar with dropping the chain inboard so I don't know what to suggest. It may be a chain issue, maybe chainrings or alignment as you say. Hope you get it sorted.
 

andyfraser

Über Member
Location
Bristol
LOL @andyfraser It's not necessarily a better explanation, just that it took a longer amount of time to type it :smile:

I'm not familiar with dropping the chain inboard so I don't know what to suggest. It may be a chain issue, maybe chainrings or alignment as you say. Hope you get it sorted.
I have a week off week after next. A whole week to get it right! lol
 
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