Chain Won't Drop onto Last Cassette Cog

LeighM

I'm running Ultegra 6800 rear mech, with an 11-28 cassette.

Recently, when shifting through the gears, I can't get my chain to drop onto the last (smallest) cog of the cassette.

My lever stops clicking when flicked, suggesting its at the limit of its range and there's no clicking rubbing to suggest it's caught between gears.

Can anyone suggest how I might fix this myself? - The bike's only 3 months old, but I have several events coming up and can't be without it at the minute to leave it with the shop.

TIA.

JayKosta

Check whether the inner cable at the rear derailleur is slack, or if it is under tension.
If cable is slack, then the 'limit screw' on the derailleur needs to be turned c-c-w to allow it to move further outboard. But first check if you can push the derailleur outwards by hand - if so then the derailleur pivot points need some oil.
If cable is tight then use the 'cable adjuster' nut/mechanism to make the cable looser.

Also the inner cable might just need a little oil to reduce friction between housing and cable.
Inspect the cable and housing for any signs of damage or kinking.

Jay Kosta
Endwell NY USA

arlowood

If you were able to shift to the smallest cog in the past and now you can't it sounds very much like you have a snag somewhere in your shifter cable. The derailleur spring is set to default onto the smallest cog so if it won't do that then your cable is caught somewhere.

You need to undo the inner cable at the derailleur and check if you can pull it any further with some pliers while operating the shifter paddle. You might also need to inspect the inside of the shifter housing to see if there are any frayed cable ends in there that could be causing the cable to snag

If you have only just discovered this small cog issue then it could be the case that the bike was initially set up incorrectly and the shifter was not clicked all the way to its final position before the rear derailleur cable was attached for indexing.

If you are happy to try and fix this on your own then have a look at this video:-

https://www.youtube.com/watch?v=SkzvfCaIbyQ

zx6man

Mine did this recently, the outer cable going into the rear Mech was the culprit, changed it and was back shifting fine. Guessing it was full of road grime.

kwozzymodo

If the aforementioned suggestions don't fix the issue, try cleaning and lubing the shifter mech. If it's a bit gunked up the mech may not be releasing all the cable and therefore stops the rear mech reaching its outermost point.

Monty Dog

Sticky cables - try cleaning/lubing the cable first, particularly the one to the rear mech

dennisn

LeighM wrote:

My lever stops clicking when flicked, suggesting its at the limit of its range and there's no clicking rubbing to suggest it's caught between gears.

When you say that it sounds like your chain is in the wrong position. i.e. as if you took the rear wheel off with the chain on the last(smallest cog) and put it back on with the chain on the next gear up. This puts your shift lever in the wrong position. i.e. it was in top gear position when you took the wheel off now you've remounted the wheel one cog off.
Key words in this post are "sounds like". You can check for this by shifting up to the biggest cog and the trying to shift even higher. If you get another click up top this is most likely your problem.

jgsi

A good setup should have the chain find the smallest rear cog anyway when putting rear wheel back and turning the cranks a few turns to settle it back in.
I cant give anymore advice to OP other than get the bike checked over as regards the rear shifting or your eventing will be less than happy.

dennisn

JGSI wrote:

A good setup should have the chain find the smallest rear cog anyway when putting rear wheel back and turning the cranks a few turns to settle it back in.
I cant give anymore advice to OP other than get the bike checked over as regards the rear shifting or your eventing will be less than happy.

I don't buy that. I'm thinking you need to pay more attention to which cog it comes off of and make sure it goes back on the same cog. Or click you rear shifter(when the wheel is off) until the rear "D" stops at it's outermost position , THEN make sure the chain actually goes on the last cog. It's not unusual for the chain to get on another cog while replacing the rear wheel. In theory simply pedaling it will put it back on whatever cog you removed it from but not always.

jgsi

Fair enough... due to having just 1 bike and too many wheelsets, I am probably swapping rear wheels on average perweek, well quite a lot and never had a problem, but then again I always ensure that chain is on small/small combo before fartin about... I'd be a very bad tempered road mechanic, if riders who punctured and wanting a wheel swap within 20seconds hadnt done this before stopping at the verge..

LeighM

Thanks for the help, guys. I think something was stuck, although I've managed to clear it for now at least.

The mech's upper and lower limits are ok, so I twiddled with the cable adjuster until all the gears selected correctly. This was a bit hit and miss at first, but by adjusting 1 or 2 clicks at a time, I worked it out.