illusiumd

So I got some Microshift Shifters with my bike this fall and it was running fine with two trim modes on the little cog and two on the big cog in front. Took it in for cleaning/basic tune up and the mechanic messed it up so that when I shifted into the big cog up front it went too far and chain came off. So took it back in and they guy was like, "you know - there's a trim on here - " and I was like "Yes, trim isn't the problem - the problem is you messed up the tune up."

So I think he just got frustrated and now there's no trim on the big cog in front. When I shift up to the big cog it just sits sort of in the middle. Now after I shift up - when I click one down instead of trimming it just goes straight to the smaller cog.

Can you do that? Can you turn the trim off somehow on the front derailer? I'm not sure exactly what he did - and it really doesn't bother me except for the fact that I'm sure he did it cause he assumed I can't understand the trim. Which may be true - so here I am trying to expand my knowledge.

TrojanHorse

Yeah, you should never be able to shift off the large chainring. Ideally, the furthest right position will keep you from chain noise and shifting off the large ring when you're in your big / small combo (highest gear). Then, as you shift from your 11 cog to 12, 13, 14, sometimes you start to hear chain rub on your FD and trimming the FD slightly inboard will make it quiet again.

So your mechanic is blowing smoke up your derriere.

I don't know how microshift works, but my SRAM shifters only have one trim position on the large chainring, and I have to shift all the way through it and THEN trim... I can't shift directly to the trim position, which is why I think your mechanic is full of it. Yours may work differently.

My advice to you would be to find some youtube videos on tuning microshift FDs and go give it a whirl. Clearly, you can't do worse than your mechanic and it's not particularly hard to get it right either.

illusiumd

Thanks for the advice - clearly I didn't explain that very well - yes there's only one trim position. There's a shift up, then a trim. I guess what I don't understand the most is how he removed the trim completely. Thanks again.

TrojanHorse

It sounds like he over adjusted your FD limit stops so you can't even get it as far as you need to shift, which is a dick move IMO. Maybe the range isn't great enough for trimming now? I'm really not familiar with microshift but most FDs are very similar in their operation so if I got it wrong, I apologize.

chaadster

Agreed, mech is a jerk and dumbass. Shouldn't have been able to overshift in first place, and should have had trim after 2nd adjustment. I hope you can go to another shop, although as stated, DIY shouldn't be difficult if you're inclined to do it.

dr_lha

Typically if you over tension the FD cable, the trim function will be lost.

illusiumd

Thanks again for the advice. Not sure where to begin if I went DIY. Maybe just play around with the limit screws on the first shift to the big cog until I can find a trim?

I usually stay away from FD/RD adjustments cause I so don't know what I'm doing and I'm OCD like a racoon.

chaadster

As was noted above, YouTube videos is a great place to start. I would not futz with the limit screws at this point, because as @dr_lha mentions above, it's more likely a cable tension issue. I'm not familiar with Microshift either, but derailleurs are not that hard to adjust once you understand the constiuent parts and functions, so I'm sure you could learn to do it in short order!

dr_lha

I've used Microshift derailleurs. They work the same as every other derailleur.

illusiumd

All right I'm going to give it go! Thanks for the advice. So start with the cable tension. What I don't understand is if it's cable tension - why would the trim on the small cog be unaffected?

I'll def look into the videos when I have time.

Fly2High

I like the GCN guys and here is their front derailleur video.

https://www.youtube.com/watch?v=Ea03ChN-7Vg

dr_lha

The cable has less tension in the small cog?

illusiumd

Nice Link muchas gracious. What's the crankset ratio on that bike?

digibud

I hope you can find a better bike mechanic. You may be able to fix this on your own but next time you have something you can't handle or don't have the tools for it would be good if you had a good mechanic to take your bike to. Clearly this fool is not competent. I'm not a pro but even I would carefully check to see that you had full trim in both directions, particularly if a person brought the bike back to me after I blew it!

indyfabz

Back when I was a teenager growing up in da 'hood, "trim" meant something much different.

illusiumd

Well decided to go back to this LBS. Guy who previously worked on the bike was working on a different bike.

Explained the situation to a different mech and he spent about 15-20 minutes trying to get the thing to work right and finally gave up. He said he had exhausted every mechanical avenue and that he suspects it's a defective shifter/button thing. He said if you press it a very specific way it'll shift down to trim - but almost always it'll just go down to the small cog.

He was gracious and said the LBS would pay for a new shifter. Still can't understand how this bike was shifting just fine before I took it in there.

TrojanHorse

Things that make you say, "Hmmmmmm"

Sounds like it's going to work out for you though, that's good news.

chaadster

Hehehe...but it was still something you wanted!

illusiumd

Yeah right!? I found that it's just impossible to find a LBS in Chicago that isn't going to F something up over the long haul. I've been to at least five or six LBS here and had good and bad experiences. Totally depends on the time of year and the day of the week. I made the mistake of going to this LBS just as the weather was starting to turn nice cause I wanted a more of a "bath" than an actual tune-up after riding all winter. It was just the wrong time and I got a bad mech. I don't know of any LBS in Chicago where they're going to have all top-notch guys. I will say the initial build on this bike was A+. I need to take a class and start doing this stuff myself.

TrojanHorse

If by "take a class" you mean "watch youtube videos" then go for it. Park tool also has tons of great videos. Go to performance bike and get a semi-decent too set and wreak havoc on your ride! I haven't gone to a shop in years - the last time I wanted to take my bike in for a quick checkup before my first century, the shop said they had a 2 or 3 week backlog, which cemented my desire to do my own maintenance. it's not that hard.

indyfabz

LOL! True, but it was something a LBS could neither give me or take away.

cyccommute 

I get in trouble every time I say this but this is, again, a case of DON'T MESS WITH THE LIMIT SCREWS!!!! There is just something irresistible about turning those little screws on the derailer that people just can't seem to resist. What's even worse is the bike mechanic should have known better. I suspect that he thought he could make it shift "better" and adjusted the limit screws too far out which caused the overshift.

Now that I've got that off my chest, the trim function is in the shifter, not the derailer. The "click" you feel when you shift is a detent in the shifter that pulls the cable a specific amount and causes the derailer to shift. The amount of cable movement corresponds to the spacing on the gears...front or back, depending on the shifter you are using. "Trim" is just a detent that is in between two other detents and doesn't move the derailer enough to cause the chain to move. The derailer moves over just a squidge so that the chain stops rubbing in certain gear combinations.

Most of the time, the trim is in the middle range so that you can get gears where the angle on the chain is steeper. Trim has nothing to do with the limit screws and really can't be "adjusted" except by cable tension.

Since yours in no longer working, I suspect that the detent in the shifter is damaged or that the cable and cable housing may be hanging up. It's such a small cable movement that a bit of schmutz in the cable could mess it up. A dirty derailer could also make it balk. "Dirty" is relative term give the small cable movement, as well.

One other place to look is the cable housing. The strands in the cable may be pinching down on the inner cable. A small cable movement would be affected by this more than a large cable movement. One of the stupid things I've noticed about cables from the factory is that they trim the plastic back from the ends a few millimeters. I see no reason why and I can see all kinds of problems that can arise from doing this. The more common I see is the strands in the cable sneaking through the ferrule and jamming the system. The cable ends look like this



It's a really dumb way of trimming the cable.

Finally, trim is, as TrojanHorse says. You shift past the trim, then release tension on the cable.

illusiumd

Dude - thanks for the info - hard to find derail videos that discuss trim.