Slow & variable ' gear change speed '

[gavinr]

I have a new lapierre technic hardtail mountain bike with shimano gears.

They work fine, as in, they change to the correct gear almost always, the problem is changing down (to smaller circle gear) on the rear gears (derailer is it?). ... It is very slow.

It is like click, gear moves, 1 second later, the chain bites into new position

This 1 second is the problem, and the worst thing is it is never the same duration .. I.e. I never know when the new gear setting will bite. This makes for a slow ride when you are trying to accelerate.

So any ideas where to look? This a known problem? Changing up gears (to a bigger circle) is quick and fine, it is just down.

I had a very cheap bike before that had twist gears that changed much faster and ALWAYS at the same rate.

Thanks for reading
Gavin

[Hector]

The rear derailer is spring loaded to pull the chain down to the smaller cogs. The spring tension has to not only pull the chain over but it has to overcome the friction of the cable within the housing. I would start by lubricating the derailer and clean if necessary. Then replace the cable and housing. These steps will allow the derailer springs to pull the chain over with the least resistance.

(08-20-2011, 09:09 AM)gavinr Wrote:  I have a new lapierre technic hardtail mountain bike with shimano gears.

They work fine, as in, they change to the correct gear almost always, the problem is changing down (to smaller circle gear) on the rear gears (derailer is it?). ... It is very slow.

It is like click, gear moves, 1 second later, the chain bites into new position

This 1 second is the problem, and the worst thing is it is never the same duration .. I.e. I never know when the new gear setting will bite. This makes for a slow ride when you are trying to accelerate.

So any ideas where to look? This a known problem? Changing up gears (to a bigger circle) is quick and fine, it is just down.

I had a very cheap bike before that had twist gears that changed much faster and ALWAYS at the same rate.

Thanks for reading
Gavin

[Paulius]

Also you can look up some videos on youtube about adjusting the rear derailer. Slow and clumsy gear changes mostly are influenced by a badly adjusted derailer. From my experience the lubrication of cable housing doesn't influence gear changes that much that you can notice it

[ghost]

(08-20-2011, 11:46 AM)Paulius Wrote:  Also you can look up some videos on youtube about adjusting the rear derailer. Slow and clumsy gear changes mostly are influenced by a badly adjusted derailer. From my experience the lubrication of cable housing doesn't influence gear changes that much that you can notice it

A dry inner cable and/or a cracked and worn outer will cause the gear changes to hang up. In a shop I worked at one of the easiest fixes with gear changes was with dry / worn cables. Ride safe.