For the average motorcycle rider checking and adjusting the chain tension is a job normally done themselves. I normally give mine a check over when cleaning and lubricating my chain which is normally on a weekly basis.
Chain wear and stretch is a weird one, there are so many factors which vary, all affecting the rate of stretch, and when the stretch occurs. The process of adjusting is also not a very hard task, but getting it to the correct tension first time, every time is also a tricky game.
Tru-tension sent me one of their chain monkeys to try out.
Made from a plastic moulding, with a threaded rod, plastic handle and a metal dome, it is a simple design. The kind of simple design that has you scratching your head wondering why you didn’t think of it first. The first thing to do is to work out where on the monkey’s scale you sit. This accounts for the manufacturer’s recommended tension setting, and also what chain size you are using as the common 525 and 520 have different measurements. Once you work this out, you adjust a locking ring so that the monkey won’t go past this point. Next up you need to hang the monkey over your chain. Once done, wind the big plastic handle until the stop (that you adjusted before stops against the monkey). This pretension the chain and puts the correct amount of slack in the chain. Then the chain tension can be tightened on the rear axle blocks until tight.
Once tight on the axle blocks, slacken off the monkey, wipe off any excess chain lube and put it away. By pre-tensioning it to the manufacturer’s setting the tension will be good, and correct first time around, instead of having to adjust the blocks and re-checking it each time.
Overall I don’t particularly see the need for it. Tensioning the chain isn’t the most challenging task and if you are not confident to do it, then this tool doesn’t make a difference to that. I have always done my chain tension by eye and feel, and have never had any issues.