[DonRotolo]

#25 chain is plenty strong for moat any FRC application, but due to the relatively small tooth size on the sprockets, the chain tension is very important. It weighs less than #25. Also due to the smaller tooth size, you can get more teeth on a sprocket of a given diameter.

#35 chain is considerably more forgiving on chain tension, but it weighs more than #25. It is also a bit easier to work with since things are not as small. It is stronger, but you generally do not need such strength.

Why are tooth counts on a sprocket important? The ratio of speed for sprockets goes by tooth count. For example, a 15 tooth sprocket turning a 30 tooth sprocket (via chain...) has a 2:1 ratio of shaft speeds. A 72-tooth sprocket is fairly large in #35, more reasonable in #25. McMaster.com can show you the range of sprocket sizes available.