Calculating the correct chain length for a MTB.

[Edwin Watson]

Hey Guys

 

I am chaining my chain on my 9 speeds MTB and decided I would do a bit of research on calculating the correct chain length. I have found that a lot of sites have different ways of doing it and while watching youtube videos there is a lot of debate between people accusing different video creators of doing it wrong.

 

Is the correct way to measure your new chain to run the chain along both of the largest sprockets both front and back without running it through the rear Derailleur. Then line up the chain and add 2 links and then the master link? So you giving it one inner and one outer link then breaking the link after that...

 

Some sites use the old chain to measure up?!Others use the lowest gear at the rear the highest in the front then go through the rear derailleur then pull the rear Derailleur down to a 90 degree angle and then break the link. These 2 ways mentioned here seem to me wrong and the first I mentioned to be correct.

 

Could anyone point me to a video this is actually right or a good article.

 

Hub FTW

[AndreZA]

http://bicycletutor.com/calculate-chain-length/

[Tuxstir]

smallest cog on both sides.. through the Derailleur.. get the chain tension so that it just misses the rear Derailleur wheel guide thing a-ma-jig.. and your set.

[amasendeinja]

I've only ever used SRAM components, so not sure if Shimano would be different - doubt it - so this is for SRAM.

 

Run the chain over the largest rear sprocket and the big blade without routing it through the derailleur. Add 1 link plus the quick link, i.e. 2 including the quick link, remove the remaining links and Robert's your mother's brother. Using the old chain lying next to the new one is also fine, and easier, considering that it was highly likely the correct length. Just note it will have stretched/elongated (need to choose my terminology here for fear of flames!) over time, so make sure you don't break it too short.

 

One thing to note is that if you have a full suspension bike, this should be done with the suspension in the position where the greatest chain length will be required, i.e. normally fully compressed. You can either empty your rear shock and re-inflate afterwards, or if you're lazy just a a couple of links and then go by trial and error. If you're using the old chain to measure, this comment is superflous.

 

Have fun

[Edwin Watson]

Thanks guys,I used the biggest cog method and then checked it with my old chain and was right so just went with that and seems to be right