Bicycle Mechanics - new chains too long

Just curious for you experts out there.

For new mtb chains. do some of them come too long in the box?

Is it best to shorten them.

As mine still was skipping some more as i had a new chain and cogs etc.
but was skipping.

Just would like to know or get some advice from any of you? thanks

They don't come too long in the box, differnt bikes need differnt lengths, so the the chain supplied should fit the longest required, you just need to check you have the correct chain length, shorten as required, and fasten together, with the appropriate pin / link.

For skipping, this will have more to do with the RD setup than chain length.

Most chains need to be shortened when new. If your old chain is the correct length you can shorten the new chain to the same number of links. If the new chain is Shimano or Campagnolo you will need to follow the instructions and use the specially designed connecting pin.

Obviously, the chain manufacturers don't know what bike you are riding or what gearing you are using. Therefore, they sell you a chain that will definitely be long enough and you have to shorten it as appropriate.

Park Tool offers some chain sizing methods:

http://www.parktool.com/blog/repair-help/chain-length-sizing

It's not that the boxed chain is too long, just that most folks need one a bit shorter.

Since lengthening a chain is problematic, the manufacturers supply them long enough for just about any bike, and buyers cut them to their own needs. It's the same as with brake and gear cables, or handlebar tape.

As mine still was skipping some more as i had a new chain and cogs etc.
but was skipping.

How is it skipping? Is the chain trying to shift? That would suggest a derailleur adjustment issue. Or is the chain skipping forward over the teeth on the cog? Does the skipping happen only when you stand and put lots of pressure on the pedals?

FWIW, sometimes replacing just the cogs and the chain is not enough. Once I worked on a bike with skipping, and the only solution was to replace the entire drivetrain -- cogs, chain, and chain rings.

I had an issue a few months ago with a skipping chain and found it to be the chain being too long and not enough tension in the deraillieur cable.

Chains are always too long and links need to be removed to match your gears.

Chain skipping -
1) Is your chain automatically skipping a gear,
2) or is it in the same gear and as you are pedaling, is it jumping teeth?

#1 usually an adjustment, but could be a worn chain and/or worn cassette.
#2 It could be your chain, it could be a bad link, it could be bad chainrings or cassette