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Setup Insights with Motion Instruments

What can suspension data tell you?

Our first outing with the telemetry kit was an eye-opener.

Getting actual information from the suspension to the iPhone, live and recorded was kind of like opening a door to a world of things you knew existed but had never seen. Right off the bat, one bit of information was staring me in the face.

Our first lap was also our last for the rear unit, as the "Tunnel of Doom" proved to be too tight for our chosen position. Because it was too tight, the end of the tracer shaft had bent and the coil mount on one end of the shock bent as well. Luckily, we used the carbon shield that came in the kit. This shield forced the rod to bend at the threads, which was easily corrected. The shield may have also caused the clearance issue.

Clearly, we must revisit the mounting on the Canyon Sender.

Our first test lap did give us some numbers, which were interesting, to say the least. The first thing that should be considered with any suspension setup is spring rate. Looking at the dynamic sag numbers, things seemed to point to an oversprung rear end. Which appeared to correlate to something reported by the rider of a bucking feeling coming from the back.

Revisiting the spring calculator gave us a third indicator of a possibly oversprung rear end.

It was one run, in a steep, slow, greasy zone. Do all of these variables compromise the data?

It's hard not to spin out thinking about it.

Looking at balance, I noticed that the rear had a lower dynamic sag than the front, which would be the opposite of what you would want. Did it matter that the trails were steep and slow?

The answer to this type of question is always more testing, on varied terrain, with different spring rates to experiment with.

Soon the Sender will be heading to Costa Rica to race with Coleton for the first race of the season. We honestly did not expect to get any useful data from such a short foray, but with a few training days still left before the trip, we're looking at more springs to try. I would say we are for sure being influenced by the data.

After a short convo with Rob Przykucki, creator of Motion Instruments, it was apparent that faster rebound speeds are going to be crucial for more traction at speed. Also, the bias toward the front is indeed the opposite of the goal for downhill bike setup. 19% dynamic sag in the rear is quite stiff, so we're on the hunt for a 400lb spring, the next weight down from the 450lb spring ran in the first test. As the bike speed increases, the shaft speeds will increase as well. We're a few hundred mm/s from the bottom of the ideal range of rebound speeds. If we can get the rear end set up a bit softer, we can up the rebound speed and be tracking better, also taking more weight and stress off Colton's freshly repaired shoulder.

Perhaps the biggest realization after the first go was how difficult it can be to mount the equipment on the bike being tested. While there were mounting fixtures included in my kit, there were no instructions on mounting. All the documentation I found on the product pages covered the analysis side of things, product specs, capabilities, ect.

Variation in rear shock mounting and tight tolerances between frame and shock can make mounting these units somewhat of a journey. I can see how getting creative with mounting will be required in many situations. The forces in play are just too much for zip ties and double-sided tape to handle. Two solutions that have been suggested are 3d printed fixtures and sheet metal with proper tools for cutting and bending. Moving forward, no single solution is the answer for all bikes and experience will become more and more invaluable.

Keep an eye on this space for more on the subject as the race season ramps up.

Dan Shell

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