skipping gears under load

[Big boy]

Hi all every now and again my bike seems to skip a few gears, from memory it skips to a higher gear.
Now theres a cable guide unde rthe bottom bracket thats made of plastic, at least the front derailer cable passes through it.
Its not tightened down could this be the culprit??
Bike is 14 spd and not done a lot of miles..

 

[Pauluk]

It sounds like the cable tension needs adjusting. Is it the rear gears that are skipping? If you have barrel adjuster at the rear derailleur or at the gear changer end, you may be able to adjust the cable tension with that.

 

[HovR]

Tighten the cable guide back down to start with. It probably won't fix it, but it needs to be tightened back down anyway. If this doesn't fix it, read below.

Skipping to a higher gear generally means there isn't enough tension in gear shift cable. Unscrew the barrel adjuster in half turn increments until correct shifting is achieved. Remember or mark where the original position of the barrel adjuster was, so if adjusting it doesn't fix the issue you can undo the change.

Is this a new bike/new cables? This is a pretty common thing to happen with new cables and bikes whilst everything beds in.

 

[PpPete]

or really grotty old cables - too much friction, and it takes a while for the spring in the mech to pull back after you've shifted the levers.

 

[Big boy]

Its a newish bike probably done under 500 miles, i will have a look tomorrow at the following.
Firstly the cable to make sure its not binding , only because i replaced it (used original on another bike.)
All tips seem good will check tension etc and adjustments.
Above all thanks its apresiated.