Monday, February 4, 2008

More on Active Spokes

In my post on Active Spokes below I mentioned that my son, Dirk, was the lab rat for the field tests that were done to see what the effect of the device was in the real world (roll down tests were also done). Dirk completed two runs within a workout once or twice each week on a standard, rolling, 4.3-mile course in Boulder, CO. He would warm-up riding to the start position and then ride the course holding about 330 watts. At the completion of the first run he'd go home--a short distance from the course--and change to another wheel. In one run he would use the Active Spoke technology and in the other he would use the same type of wheel only without the Active Spoke. On some runs the Active Spoke wheel would be run first and on other it would be second. There is a weather station next to the course. Dr. Joe Voelkel from the Rochester Institute of Technology who set up the protocol and monitored the testing, checked the online wind reports from that station in order to better understand the external variables affecting the results. This testing went on throughout the summer of 2007.

The accompanying chart is from one of those tests. In run #1 the standard wheel (without Active Spoke) was used. The Active Spoke wheel was used in run #2. There were 24 minutes between the runs. These two runs are highlighted in black. Notice that in run #1 he averaged 334w and his time for the run was 9 minutes, 35 seconds. In run #2 with the Active Spoke he averaged 327w but was 48 seconds faster (8% improvement).

To check what he was seeing in the tests Dirk did one of the Wednesday night, 10-mile time trials (same course) with the Active Spoke and posted his fastest time ever, the fifth fastest of the summer's series results. He used a road bike with clip ons and had a 53 big chain ring (the other fast rides were done on aero bikes with 56s). At age 37 he is far from being one of the youngest guys in the Boulder race. He is thoroughly convinced of the benefits. (Go here to see the results from that race.)

Here's what he had to say about the race: 'When I crested a hill and started to accelerate, the weights transferred to the rim aiding the acceleration. I would actually feel the weights hit the rim and in some cases it meant I could shift to a bigger gear. It literally is like a small turbo booster.'

This field study will continue as soon as the weather in Boulder breaks. For more details go to


At February 5, 2008 2:16 PM , Blogger Mark said...

Hi Joe: Do you have more info on what course profile works best? Intuitively I guess the active spoke is good on rolling hills while disc wheels are better on flat courses and a traditional wheel is best for an uphill time trial.

At February 5, 2008 2:36 PM , Blogger Joe Friel said...

mark--Yes, I'd agree with you in general--for steady state events. Whenever acceleration is important (long climbs, lots of corners) a light wheel will work best. When aerodynamics are important a disc is the way to go. For rolling courses Active Spokes have an advantage. Combining a disc with Active Spokes has great potential, I think.

At February 25, 2008 9:03 PM , Blogger Adam said...

"the weights transferred to the rim aiding the acceleration. I would actually feel the weights hit the rim and in some cases it meant I could shift to a bigger gear. It literally is like a small turbo booster."

This is specifically prohibited by USAT rule 5.11 (h) Which states"No wheel may contain any mechanism which is capable of accelerating the wheel"

Just seems like the set up is to not be allowed unless some money gets put in the rights hands or something. I only assume that these wheels would be illegal bc when the spokes "engage" the power input would then either go down or stay the same with rotation going up. Just a thought.

At February 26, 2008 5:55 AM , Blogger Joe Friel said...

Adam--I understand that it was just approved by Charlie Crawford who oversees rules and officiating at USAT. I don't believe there's any bribery going on.


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