I've seen a couple of references to the "90 degree" method of checking the belt tension, but I haven't found a procedure. Can someone elaborate or supply a link? I went through the tech section buy I may have missed it. Thanks.

Serowbot wrote on 04/05/11 at 10:12:28:

Ok stupid question: One or more fingers together with the thumb? Makes a big difference. With just one finger, I hardly manage to get it to 90 degrees. With two fingers it's easy.

Serowbot wrote on 04/05/11 at 11:06:26:


That helps. I don't know why they don't just list a belt deflection specification. I don't have the tension tool in my toolkit.

Serowbot wrote on 04/05/11 at 11:06:26:

Actually in my case the belt chirps more the looser it is. Mine is set so I can twist with my thumb and two fingers to barely 90 degrees. With the rear wheel off the ground it shows that this is about right, as when turning the rear wheel, it spins completely effortless still. So that method is pretty much dead on. I waited and did this on a day, when it was about 68 degrees outside. Most everything in industry is calibrated at that temperature. I adjusted the tightness and alignment. Point is, that the belt is affected by temperatures with shrinking in the cold and expanding with rising temperatures. It also seems to affect how true it wants to run in the middle of the pulley. I aligned it running in the middle when it was about 68 degrees outside, and it proves to work just right. Especially now that it is spring time, with temperatures in the low 30's in the morning, and up to 75 degrees in the afternoon. In the morning the belt runs on the inside of the pulley. Around lunch time it runs more in the middle, and later in the afternoon when temperatures peak it runs towards, but not all the way on the outside. It works every time. Now every time I have to take the rear wheel off for a new tire or other things, I take my caliper and measure each side of the adjusters and write it down. When I put the wheel back in, I adjust it to the specs I wrote down, and it's dead on every time. No more adjusting for hours anymore. this also shows that the alignment marks on the swing arm are pretty inaccurate. One side is in front of the large marking, and the other side is behind it. When I first got the bike I used the markings and the tension tool and that just rewarded me with terrible squeal. The way I do it now minimized it to virtually no squeal most of the time, except on moist cool mornings for the first mile or so.

90 is only good for tension NOT alignment..
all my chirps are from inproper ALIGNMENT..
i use spray on silicone belt dressing cause the wild variable temps here in weatern colorado affect alignment more than tension..


(its a tough belt BUT on the laterall expansion and contraction is not consinstint)

I checked it last night. I don't quite get 1" of upward deflection, more like 3/4", but I'm not going to mess with it right now. It doesn't chirp or anything. I can get it to 90 degrees with a little effort (not easily do-able with just a thumb and finger).