Drag Factor

[sgat_555]

Hello Everyone!

This is my first post so apologies if this has been covered previously.

I have just upgraded my trusty Model B with a PM5 (Christmas present to myself). Everything seems to be working perfectly however, when I check the Drag Factor, it's 243 with the vents fully open and 170 with them closed.

I've never checked this before (PM1) and based on numbers I have found online, this seems a little high. Does this mean my machine needs a monumental clean/rebuild?

All the very best, Stuart

[Tsnor]

Did you configure the PM5 for a Model B ? Apparently a different firmware setting is needed and if you are set for a model D you will get funny results.

Edit: here is a video: https://www.youtube.com/watch?v=ksbcVg0jPG0

[sgat_555]

Tsnor, thank you for the prompt reply!

After getting an unexpectedly Drag Factor, I searched the PM5 options and found the Model selection. It's now set to Model B, however this had little effect on the Drag Factor numbers.

I've just been searching the forum posts and noticed people who have "enclosed" their Model B machines to replicate the newer model. Could this be the reason for such a big difference compared to the reference values online?

Thanks again, Stuart

[Citroen]

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You want to find a "speed ring" (or fabricate a substitute) to bring the model B drag down to the range you'd get on a model C, D or E.

[sgat_555]

Thank you very much for the links. I'll make a speed ring and see where that gets me.

I've just been playing with the PM5 settings. Interestingly, when I set it to Model B and confirm, if I go back into that setting it has reverted to Model C. By comparison, if I select Model A or Model D/E and go back into the setting, it has kept these options. Am I doing something wrong or do I need to update the software? The unit is only a week old so I would presume the firmware is up to date.

Thanks again! Stuart

[Citroen]

I go back into that setting it has reverted to Model C. By comparison

That's expected since the model B & model C sensors are identical (flywheels aren't). With the model D & model E the whole flywheel and sensor assemblies are identical.

Depending when the unit was built (if it was before Sept 2020) the firmware may be stale.
https://www.concept2.com/service/monitors/pm5/firmware

[JoeCruse]

I just ordered a PM-5 for my model B today; I'll be interested to see DF on mine. I cut some roofing paper up to make a cover to surround the area outside the damper and the circumference of the cage. It REALLY made a difference! I'll pull it back off once the PM-5 is installed, and get some DF readings, then re-install my speed ring and check the DF again.

[sgat_555]

It would be great to have a direct comparison for reference.

I've used this Model B for 15+ years and I have always been happy with the resistance (even with the vents fully open). The DF has only been something I have been aware of since fitting this PM5. It will be very interesting to see what the feel is like after making a cover/speed ring to match the DF to more modern machines.

Thank you everyone for the assistance!

[dsamant]

C2 has the damper comparison chart on their website at https://www.concept2.com/files/pdf/us/t ... arison.pdf

This is assuming you have the speed ring (either handmade or purchased as a part from C2) installed on the Model B.

[c2jonw]

The B flywheel does have a high drag factor range, but the B also had two sprockets- a 13 tooth and a 15 tooth. Model C/D have a single 14 tooth sprocket so comparatively speaking the "feel" of the high drag factor of the B is increased when on the 13 tooth and reduced when on the 15 tooth. It still has a pretty heavy load range and it was at the request of many rowing coaches that C2 developed the Speed Ring for the B.