Problem shifting to low gears

[euan1984]

Hello all,

I have a giant road bike and am having a problem when shifting to my cog for my lowest gears... the top cog and middle cog on the pedals are fine, but when I try to shift to my lowest gear ratio, I have to play around with my gears until it finally clicks in after several minutes... Obviously nthis is not good news when starting a climb!

Does anyone know why this problem may exist and how it can be rectified? Is this because the chain may have stretched over a period of time?

It can be quite frustrating and I would enjoy my cycling much more without this problem. Any help would be appreciated.

Thanks,

Euan

[geegee]

I imagine you are taking about the chainrings and the front derailleur. You just need to properly adjust the front derailleur, checking that it is properly installed first or that the height and the angle have not moved over time. A lot of problems regarding the failure to shift into the smallest and largest rings is due to the adjustment of the high/low limit screws. there are tons of videos on YouTube that can help you with this, just enter "front derailleur adjustment" in the search

[whittierider]

Very common problems are that the front derailleur is too high (it should come within a penny's thickness of the big ring at the closest point as it swings out), or that the derailleur is angled in (the lower rear tip of the cage should stick out slightly farther than the front, not have the outer plate quite parallel to the big ring), or, in the case of indexed front shifting, possibly how the cable is clamped on the derailleur.  I had problems with the front derailleur of our tandem for the whole first year of ownership, then someone on the tandem forum gave me a tip about anchoring the cable slightly different from how Shimano said to do it.  That was the end of the problems.  It has worked perfectly in the years since then, with no maintenance at all.  Note that the cable goes to the right of the little nub sticking out by the top bolt, instead of to the left.

[johnsondasw]

And if you can't figure it out, take it to any bike shop, and they should be able to take care of it in a few minutes.  It's probably a simple screw adjustment, as indicated by geeg.

[whittierider]

And if you can't figure it out, take it to any bike shop, and they should be able to take care of it in a few minutes.

Usually, but they couldn't figure out the problem I told about on the tandem above.  They basically said it's the nature of the beast, being an inexpensive triple.  A slightly unorthodox solution proved to be the perfect solution.

[paddleboy17]

One other possible problem is that cheaper front derailleurs do not like to shift under load.  So sometimes you have to anticipate the shift and down shift the front derailleur early.  If you wait until you are standing on your pedals cranking for dear life, the derailleur won't shift.

The suggestion to change the limit on the derailleur is a good suggestion.  Basically, this allows the derailleur to move with a little more kick, and this may be enough to execute the shift.

I have a cranky front derailleur on my mount bike.  I will have to try the suggestion to lower the derailleur.  It is an E-style mount, so I don't know how much movement I can make.

[MIBIKER]

  If the shifting was good then slowly got worst over time, try replacing the the shift cable and the cable housing.  When installing new housing you need to put end caps on the housing otherwise the housing will be pushed through the cable stop on the frame, resulting in poor shifting. Also  apply a thin coat of grease to the inner wire to help the wire move smooth inside the housing.The limit screws should not need to be readjusted if the shifting was working fine early in the season, unless you had a bike shop work on it and they might have adjusted the limited screws.  Also try spray some lube into the shift lever pivot. Over time the grease can become a little dry and the new lube will get things move smooth again. 
Good Luck

[Peaks]

I had that problem on my coast to coast trip.  In my case, the spring was not strong enough to keep the derailer in the lowest cog position. 

But, I agree with others that first thing is to check the adjustment.