Front derailleur headache

[atlantis]

Hi!

I have a hybrid with a triple 48-38-28 crankset, 8 speed . This bicycle was working perfectly well and also well maintained. Suddenly the shifting of the front derailleur has gone bad. That is, it does not shift smoothly from the middle chain ring to the largest, there is a lot of noise and then it shifts with a lot of effort. If i increase the cable tension which makes the lever super hard, the drop to the middlechainring becomes an issue.

If I try it on a work stand it is super smooth. All the shifts are perfect .

Please let me know what is the solution, I have worked on bicycles , and can manage some what , but I am at my wits end here.

I had changed the crankset from 42-32-22 to this one, and the shifting was perfect for quite some time, until this happened.

Any help would be appreciated.

 

[Levo-Lon]

Sound like the meck needs raising?
Should be about 5mm above the large ring..

did you reset the mec when you fitted the new chainset?
Could just need the mec adjusting so you have a little more travel..as your cable is getting very tight

 

[raleighnut]

Sounds more like the mech needs a good lubing around all the pivot points, a new cable wouldn't go amiss either.

 

[Yellow Saddle]

Sound like the meck needs raising?
Should be about 5mm above the large ring..

Make that 1mm.

 

[Tim Hall]

Make that 1mm.

I use a 2p coin as a gauge to get the height (thickness not diameter, obvs.), so at the @Yellow Saddle end of the thickness spectrum.

 

[growingvegetables]

I use a 2p coin as a gauge to get the height (thickness not diameter, obvs.), so at the @Yellow Saddle end of the thickness spectrum.

Handy - now that is something I will remember

 

[Levo-Lon]

My mtb mec struggles at a tight clearence..and jams? So i go with about 5mm..tho i do just guess the gap..so it may be smaller

not that im arguing..just my findings...ahh mine has a bash..lol..so yes keep it smaller

 

[Levo-Lon]

Here is a set up guide for OP

http://www.parktool.com/blog/repair-help/front-derailleur-adjustment#article-section-1

 

[atlantis]

Thank you so much for replying so quickly !
I have done all the above , Yes the mech height and angle has been set perfectly, the bike was rolling just fine and shifting was good, until recently. I have been through the Park tool site as well no luck. It works fine on the work stand but not when under load. This is really driving me nuts, would really appreciate more inputs

 

[Levo-Lon]

How is the chain wear?..chain checker as id think it may be worn

 

[Ajax Bay]

How is the chain wear?.

How do the symptoms the OP describes link with chain wear? Why do you think it may be worn? The OP is not describing skating. Are you just casting around?
This seems like just adjusting the FD on the stand; trying it out on the road and then if not right having another go; and repeat till satisfactory. The FD may be designed for 42t large chainring and be having a small issue with the 48t but normally MTB FDs can cope IME.

 

[Levo-Lon]

How do the symptoms the OP describes link with chain wear? Why do you think it may be worn? The OP is not describing skating. Are you just casting around?
This seems like just adjusting the FD on the stand; trying it out on the road and then if not right having another go; and repeat till satisfactory. The FD may be designed for 42t large chainring and be having a small issue with the 48t but normally MTB FDs can cope IME.

he asked for more ideas...so checking the chain is more ideas..

no need to pm me like last time..Ta..you tell him whats wrong..then you can claim the prize..

 

[Ajax Bay]

Any help would be appreciated.

 

[Tim Hall]

OK, given that the bike was shifting fine with the new (toothier) chain set, the mech is adjusted fine and suddenly doesn't shift properly, I'd suggest something "traumatic" has happened. What is puzzling is that it shifts fine on the workstand but not on the road.

Does the bike have exposed gear cables ( ie inners only), running down the down tube or along the top tube? When it doesn't shift to the big ring, can you make it shift by pulling on the exposed inner?

(I'd agree that it's vanishingly unlikely that the problems are down to chain wear)

 

[Levo-Lon]

But he says its under load that the problem occures...so check the chain anyway..simple enough