+ 1 525 pitch chains are quite a bit heavier than 520 pitch chains.

Less weight means more power to the wheel, much like a lighter rear wheel (less weight to turn).

Due to the light weight, they are apparently less durable, however the chain quality these days doesnt make that much of a difference (not that I have found anyway).

Hope that helps.

E.

Iv run 520 for a year (about 5k miles) and its still like new and hasnt stretched much atall, cheeper too

the only thing is nc3*'s dont have a cush drive so if your a wheelie nutt then you will probably stretch them fairly quickly

Freekazoid wrote:i have a 520 chain on my NC30 not too sure what the advandages are of it though?? so yes definately fits, obviously you are going to need a new rear sprocket, at least thats what i know hopefully some one slightly more knowledgable can help us both. i'm interested to know what the number denote?

I think it goes like this.

A 520 is same pitch as 525, different width.
The side plates, pins and rollers are the same, the strength comes from the increased width.
A 500 series chain is 5 x 1/8", so 5/8" pitch.
The width is around 41% of the pitch. [measured between side plates, roller length]
A 520 is 2 x1/8" wide, so 1/4"
A 525 is 2.5 x 1/8" wide, so 5/16"
The thinner lighter chain wears more but absorbs less power, the tensile strengths may be 8000 and 8400 lbs/ft, but of course vary with make and special or race chains.
Race chains are lighter, stronger and more expensive.

Dave.

Spike16 wrote: the only thing is nc3*'s dont have a cush drive so if your a wheelie nutt then you will probably stretch them fairly quickly

Yup, which is a very good reason to buy the best quality chain you can afford (x-ring or whatever the latest craze is...)

Cheap ones will stretch, ruin and are false economy in the long run as you WILL be replacing them more often.