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Solo race sag method


ss-racing66

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A few years ago I came up with an idea ¬†of using my¬†iPad to take a video ¬†of a hanging measuring tape ¬†to measure and set sag solo‚Ķit worked ok ¬†but eventually I had an accident and cracked the iPad screen ¬†ūüėē

It looked like this (from my YouTube video) :

4F534EF6-D99C-4200-8EF1-E0283524823B.png.7ee7c1def33ab5fa8de5f6ca3a37f397.png

after I broke the iPad, I tried to use an old HP webcam, (shown below) with a laptop for a live view, and it worked halfway ok….the camera had a hard time focusing and was just 720p resolution…. CE199C7C-2488-4E51-B2DC-45ECC867D4D2.thumb.jpeg.42ac64951a79b2fb7a4130531c52a98d.jpeg

one of the YouTube viewers suggested I try using a GoPro and view it on my phone….I tried it recently and it works well,  have a look.FEEB166A-6E00-4DF4-9BA3-3247E223F163.thumb.jpeg.341e791f31b53407d3c5faace5315c09.jpeg

the measuring tape is a little 1/4‚ÄĚ wide unit that I simply tape to the fender, and it‚Äôs captured at the axle by a small cotter pin¬†

41027B58-1B4F-40E3-B9AF-EA74B5C942F1.thumb.jpeg.734b4fb205b271066beb554a9eaa0eba.jpeg

set the camera on a small tripod , jackstand, block of wood, whatever… so you can get a accurate look at the tape through the camera

14D8A629-E929-4A19-825A-4062AEEC75C3.thumb.jpeg.2cfa82193bdc673ed8442352cb49f594.jpeg
 

B8B82D75-F1F5-4615-8F7A-B5785DF4C0A7.jpeg.521a35c7609e9c3e7fdcfdd16e41ce7d.jpegthis is the real-time preview through the gopro app on my phone…

What I usually do is start measuring on the stand and adjust the tape so it reads 705mm at the axle. Then take the bike off the stand and I expect to see about 670-675mm , then I  sit on the bike with gear and  adjust the spring preload for 600mm, which gives me my 105mm of race sag. 
you can do a video with your phone  as well but I really like the idea of looking at a real-time image 

Hope that helps

Edited by ss-racing66
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5 hours ago, Hans Schmid said:

Motool Sag Scale 

Motool 3080-103 Slacker Digital Suspension Tuner V4 with Bluetooth. Works on street, off-road and adventure motorcycles. https://www.amazon.ca/dp/B08B1FXQC7/ref=cm_sw_r_apan_glt_i_KW7HWYMYWNJ47V9HVN9R

Those are nice , they’ve been around for at least a couple years, but I can’t justify the cost when I might only use it once a year

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I use almost the same method. 
My difference is that I attach the begging of the tape measure to the axle, and take measurement up top on the fender. 
With a phone on a tripod I record the video. Live viewing with two devices would be nice, but my method is routine by now so I don't find it necessary. 

I've used that Motool scale once, and while it produce results, it is so low-tech that I'd never consider it at that price. Chinese could make a better device for 10$.

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