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Bike Fit Arsenal: Rock ‘N’ Roll Spin Scan

Bike Fit Arsenal: Rock ‘N’ Roll Spin Scan

One of my recent quests has been to acquire a side-to-side rocking bike trainer to replace the Computrainer currently used on my bike fitting platform.  The reason is simple: more realistic rider motion that mimics two-wheeled balancing on the road.  It also aids in seeing functional asymmetries which i’ll talk about in a later post.  The sticking point was that I prefer to keep core software features of Computrainer such as Spin Scan, which is software that quantifies pedaling efficiency and power distribution between each leg.  Inevitably this meant Computrainer hardware had to be rigged onto a new setup if  features like Spin Scan were to be retained on a side-to-side rocking frame.  Steve Hogg found a clever way himself which involves a Lemond Revolution connected to a Velotron.  This method works great, but a more affordable yet effective solution was needed in my case.  Eventually the idea came to mind; mount a Computrainer load generator onto a Kurt Kinetic Rock and Roll frame.  In theory it made sense, so with the help of two cycling friends, one an industrial designer, the other a power equipment service manager with a garage filled with tolls, we made it happen.    Before I illustrate, check out what the Rock and Roll does in this video clip:    (skip to 2:09)

So the job was to make an adapter which allowed us to:

Take this: Computrainer load generator

And put it on this: Rock and Roll Frame:










Trimmed away material no longer needed and prepped Kurt Kinetic frame












Cut two 2″ sections of angle iron:












Which then mounted on both sides of RR frame here:












Drilled mounting holes in angle iron:











Bolted-down angle iron

Welded back plate for dial adjustor to press against:









Painted the finished adapter – why not?











Then it all came together as planned..









And there you have it! Works great and now added to the Bike Fit Arsenal. Rock and Roll Spin Scan.

Rock ‘N’ Roll Spin Scan from GreshFit LLC on Vimeo.

More details on bike fit

Gresh Fit says:

Hi John,

It doesn’t have an impact on calibration. The load generator is slightly higher on rock n’ roll, but calibration simply measures “press on force” in pounds per square inch so placement is not critical (unless maybe if it were on top, which I can’t see how/why that would happen anyway). It has been working great for me and haven’t had any issues. definitely a good CT upgrade! Most importantly (for me) it has provided key insight to rider function during bike fits.

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