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[yhafting]

A few thought after having changed the belt:

At first i tried using the wheel alignment as it was before the first belt snapped. After buying all the proper tools for doing the job, i tried readjusting both the belt tension and the wheel alignment.

I noted a few things i believe would be useful to anyone trying to perform this adjustment, or measuring the belt tension.

First of all, turning the bolts for the wheel alignment will alter how close or far from the rear sprocket "wall" that the belt runs. At first my belt was hugging the wall, but after adjusting i found i could manage to get it 1/2mm or so (enough that there is a visible gap, but not enough to get a fingernail in between). Adjustments in the range of 1/6 turn of the bolt may be significant.

The initial belt tension was slightly too tight. However it is easy to be fooled using a belt tension gauge (any), as the belt tension will be significantly different after turning the back wheel forwards compared to backwards, and possibly depending on the side of measurment.

I do believe it is the lowest achievable tension having a stationary, off-ground back wheel that gives the most correct measurment (to avoid the risk of ratcheting). An alternative interpretation of the manual would be that the minimum should be 20 and the maximum 30kg tension, which may be possible to achieve.  However i am not confident on gambling on the latter, as i have already reduced the belt tension to achieve approximately 25 to 35-40 kg belt tension.

I have added a short note on this on the unofficial wiki.

I have read posts here where people claim that the factory installed belt was much more tense (40-50kg) compared to the 20-30kg manual specification. I ponder whether this may be due to measuring on the tense side of the belt. Similarly, i believe a a readout of 20-30 kg may be too weak (possibly causing ratcheting) if the measurment is done while the bike is on ground or after moving it in the wrong direction compared to the measurment side.

As there is no clutch to release tension caused between the engine and the wheel, care has to be made in order to achieve a good measurment of the belt tension. Running the back wheel either back or forward between measurments will reveal this, however one could argue what makes the best practice for doing this measurment- whether it is as i tried (using the lowest measurment after moving the wheel back and forth a few times), or whether one should always remove the rear wheel mudguard to always make measurments on both sides and then calculate the average, or position the rear wheel in order to have the exact same readout on both top and bottom side.

Thoughts on the topic will be appreciated...

[Kocho]

If the rear wheel is off the ground, would it matter if the tension is measured on the "pulling" or "pulled" side of the belt? I expect there wouldn't be any difference whatsoever.

[yhafting]

If the rear wheel is off the ground, would it matter if the tension is measured on the "pulling" or "pulled" side of the belt? I expect there wouldn't be any difference whatsoever.

I was a bit puzzled by this to, since the rear wheel rolls quite easily when the belt is detached. But i repeated the test several times, by rolling the wheel forward/ backward by hand between measurments. As long as the wheel is stationary readings in one spot is consistent, but the slack was visibly different after turning the wheel, thus the friction may be significant still. 

One could of course argue that this may happen if the motor and its sprocket may was not properly secured in my bike, but i cant see how that might have happened, as i have not touched those at all. I do believe i would have felt if the belt was creeping up on the edges of the motor sprocket, and i was visually inspecting the rear sprocket at all time. ..

[Kocho]

Well, I got the belt tension tool and my belt seems very tight. The "spike" on the tool barely moves up, pretty much pointing to the highest tension. That's way more than it should be. Any chance I am not measuring right? I am pushing up, approximately in the middle of the belt on the bottom of it, with the "lip" of the tool hooked-up.

If I do continue to press harder after the "click", the belt deforms more and the tool measures a smaller pressure, which is expected - it thinks the belt is deforming easier than it is. So I think I'm using the tool right, just the belt is very tight and barely deforms by the time the tool clicks. Or the tool is defective...

[yhafting]

Well, I got the belt tension tool and my belt seems very tight. The "spike" on the tool barely moves up, pretty much pointing to the highest tension. That's way more than it should be. Any chance I am not measuring right? I am pushing up, approximately in the middle of the belt on the bottom of it, with the "lip" of the tool hooked-up.

If I do continue to press harder after the "click", the belt deforms more and the tool measures a smaller pressure, which is expected - it thinks the belt is deforming easier than it is. So I think I'm using the tool right, just the belt is very tight and barely deforms by the time the tool clicks. Or the tool is defective...

It is relatively easy to get it correct, and i believe you did. If in doubt, try see MostlyBonkers video:

If by chance the lip is on top of the belt, you will apply uneven pressure to it- but that is pretty obvious if done wrong. The lip seems to be there so it is easy to align the tool to the belt. Do also try measure in the middle of the belt from the bottom side (easiest access). If you are not in the middle, the readout will be higher than the tension actually is.

My bike was also too tense (i saw that after changing belt, so in theory it could be the new belt being tighter), however i believe the first belt was too tight too. I adjusted mine so that i would read around 25-35 (depending on which side i measure/ or how the wheel stopped). This meant releasing at least one full round on the nuts adjusting the belt tension. 

Do not push further after the click (to avoid damaging the belt), just release gently, so the bar doesn't move.
 
If it requires very little effort to get the click there is probably something wrong. For my part id say it would be inconvenient for using a single finger if it was any harder. 

[Say10 15FX 16FXS]

Here is another link on using the Kricket with detailed instructions.

http://www.newenglandbelting.com/bt_method3.asp

[JaimeC]

Thank you for that link.  The photographs are MUCH clearer than the ones actually provided with the device.  Those looked more like B/W Rorschach tests than anything else.