Awesome job very impressive.800 samples per 5 seconds. That means it is 160Hz? The SRM cranks we use at work are maximum of 10Hz I think. Does that seem right?
In regards to 4th pic you said you set cadence to 60RPM. Do you have to ride at a certain RPM for it to work or does it work out power based on whatever RPM you are riding at the time?
It calculates based on actual RPM when I use it outside.
The 4th picture of the graph had a 60rpm cadence value set because I had to physically wire it to my laptop to print the graphs live, and I couldn’t actually spin the cranks when wired up to my laptop.
This forum(screenshot below) has info saying that they get data at about 60-200Hz, which seems around what I have too.
10Hz might be the rate SRM sends data to a head unit?
I tried a moving average calculated at every sample, but this took a lot of memory on the arduino in order to get a few seconds worth of averaging data saved, and I had a hard time setting the exact averaging duration since it was based on the size of my data array. I got frustrated trying to fix it, so I went the other extreme, with cumulative power / number of samples refreshed every 5 seconds, with none of the power values individually saved.
Refresh rate of .2Hz :o
It is quite slow to respond as it is right now; I’ll need to make a compromise next time.
I think you are right that the option to display data is at best 10Hz. I couldn’t find any definitive data on what the sampling rate was.
By quite slow to respond do you mean that you cycle for a few seconds before the power is displayed for that point in time?
Yeah, it only displays a new value every 5 seconds. For biking it is fine for me since I mostly want to know approximately how much power I’m putting out. For unicycling, I’m not sure what will be best yet.
Current progress is that KH cranks are so stiff that it’s not working for me!
Which also means my bike’s powermeter is also probably not accurate even though it does give me readings.
I did everything the same as my bike, but on 110mm Spirits. If I bend the crank by hand, I get a tiny reading, so I thought it’d work. When I mount the crank, and add 25lb of weight, I get 0 torque when the crank is at 3 o’clock, but oddly I get a significant reading when the crank is at 12 o’clock.
I read somewhere that any forces in ‘off’ directions cancel out in other powermeters, but I didn’t really think about this when laying out my strain gauges. I’m guessing this is the problem, since KH cranks are so stiff and 110mm is so short.
The KH one is torn apart at the moment. I will have to go back to my bike and test that more first.
Wow I never would have thought that would be a problem.
Pedal power meters exists so would the problem be the crank being too short? The pedal power meter must get torque from a tiny distance?
Installed power meter on the left crank, 125mm KH spirits.
I don’t have a way to log more data yet; only using strava. I can ride the hill recording either net, positive, or negative power.
Today, my first ride was using net power.
I didn’t use my brakes on the downhill at all.
I think it was estimating low, by about 20W. Before and after the ride, I spun the right crank to about riding speed, and it was saying -20W.
However, after looking at it more right now, it doesn’t seem right…It should have gave me about 5W overestimate… Not sure what’s wrong.
I think it’s cool that the total average power was about 0W. 
To do:
Very cool!
That is a fun way to summarise a uni ride: 0W like in the couch
Joke aside, it sounds like a powermeter needs to take into account the uni specifics of back pressure by registering all measurements as absolute value.
It is nice to follow your experiment 
That is interesting. Normally, for a bike, if your foot that is on the upstroke is pushing and not pulling, that will detract from the powermeter’s measurement.
Even though it does tire the rider out, just like going downhill on a unicycle. However on unicycles and fixies without brakes, that is much different when going downhill since we are forced to backpedal.
I’m not sure what exactly is the best way to do it.
One possible take is just letting it go negative, and looking at rides in segments. The reason for this would be so that, someone who is backpedalling vs speeding down a hill, won’t have the same power reading.
I’ve been trying to get a power meter on my unicycles for a while now.
3 has been the best, which I most recently used at Mt. Diablo challenge. Data seemed decent. Used a similar weaker setup at Colorado Muni Weekend, but the 3D printed adaptors got destroyed pretty quickly.
Just saw this is in my email… price is double of the Favero Assioma’s, but seems to be a much better solution without the pod and hack-y adaptor. $1300 for flat pedal power meter seems crazy compared to other powermeter prices currently though.
Ok call me a Debbie downer but I just can’t take another minute of this thread. I love unicycling as much as anyone on this forum. when I was 12 years old I rode a Columbia unicycle with cottered cranks on a 24 inch wheel and a square curved seat for miles on end up to 15 miles at a clip. and I rode a very steep hill that i could not do on my bike to my best friends house on my unicycle almost daily,. I reference this just to show what you can do with a basic unicycle and ambition . Today I ride a variety of unicycles from 20 to 32 inches and of various ages and qualities.at age 53.
What is all this leading to You may ask? we are all riding no matter what size , quality, or configuration the unicycle which is a very simple machine i would argue just one notch up from a teeter totter ( simple lever). I am always amazed at the constant need to try and make it so complicated . The need to turn this into a ball of complicated equations is beyond me. All I know as a unicyclist are 2 equations, the first being : rider + unicycle + lots of practice+ lots of energy exerted +scraped knees and broken bones = a very low speed mode of transportation. On the other hand this equation works better for me: rider + unicycle+ lots of practice + lots of energy exerted = a very challenging and rewarding hobby. The constant quest to shave a gram here and a gram there or a few. Millimetres in crank length to gain a small increment in mph or kph is utterly ridiculous. You will reach a level of comfort riding on equipment you like (and you will find that through trial and error) in an environment you like and this will deliver you your Max power output. You will know it when that comes together, a $1500 sensor can’t deliver that and honestly what will this info really and I mean really, actually give you to enhance your experience as a rider, you can only ride to your skill level, information can’t make you a better rider. Oh yah, a unicycle in a wind tunnel is just ridiculous i would love to see that, Sorry just my opinion.
Now go out and ride the style that suits you on a uni you are comfortable ridiing and push yourself as much as your comfortable doing and enjoy the ride. Your heart and sole are the best meters money can buy.
No. I think aerodynamics is what’s been holding me back. A time trial helmet and elliptical spokes should get me to 7mph and beyond.
I used to think very similar to that, but then I started running and taking endurance sports more seriously. “Heartrate monitors - pff, who needs that, I know best how hard I’m pushing myself.” - and then, just out of couriosity, I tried one, mostly to prove that it doesn’t tell me anything I didn’t know. Turns out I was completely wrong, and I could learn a lot of things that I didn’t know from it. Heartrate monitors allowed me to develop a feel for pacing that I didn’t have before. Now that I’ve learned how an effort that I can sustain for any given time feels, I don’t need to check my heartrate much.
Sure, I could have learned that the old fashioned way - stopwatches, tracks, talk tests, time trials. That works, but would have been a lot slower of a learning curve and required me to do at least some of it in boring controlled enviroments. Looking down at my gps watch from time to time is something that I could do anywhere and didn’t distract me much from actually enjoying the run.
There are certainly people who have much more of a talent for pacing and endurance, that can figure out all that stuff without any technological help and people that were a lot faster than I’ll ever be in times when running shoes had leather soles and GPS didn’t exist. That won’t keep me from using the tools I have available to make me a better athlete.
Of course, you have to be a bit carefull of some things:
I personally have no desire to have a powermeter on my unicycle (I don’t particularily enjoy unicycling as an endurance sport anyway), but I can understand someone that does. Is it completely nerdy and overkill? Absolutely, but I have the feel that looking at data and cobbling together parts is fun for @unicycleharry . Might not be your kind of fun, but there are stranger hobbies to have.
For me, Unicycling is the place where I’m pretty good at not going full nerd (anymore), but I can completely understand going down the rabbithole and wanting to science out the details in something - which doesn’t have to make it less fun.
Finishing note: I’ve been able to do a lot longer days/weekends out riding on a unicycle because I’ve nerded out on endurance training for 1.5 years. Previously I would always hit a wall at the end of the day and start the next day tired on a Muni weekend, now I’m able to get the most fun out of every day without giving up anything. That’s pretty good return on investment in my book, especially since I enjoyed every step of the process of getting to this point.
Personally, this subject interests me. I love unicycling, its techniques but also its physical aspect.
For someone who is looking for performance and who spends time thinking about the unicycle, it is an additional tool.
I find it an interesting tool to analyse a hill race or a hill training. Even more so when it comes to comparing them with similar efforts on a bike. But it doesn’t really have any other applications. I would have liked to have the power data on my hour record, but that’s just curiosity. It would be interesting if there was more choice on the material, especially on the gear.
Ok Maybe I’m speaking for the average rider and not for those of you that are riding at a very high level and competing looking for an advantage . Maybe I’m just speaking for myself I shouldn’t presume anyone shares my ideas. I just do not find over complicating unicycling beneficial to the average rider. I am starting to realize unicycling seems to be a sport dominated by engineers and techies, which is fine i just don’t fit that mold.
I feel like it’s the engineers and tinkerers that dominate the forums, there isn’t a lot of representation from trials and street or flatland on these forums and those guys don’t complicate anything really. No brakes, no water bottle holders, no odometers, no power meters, just a wheel set, frame, and seat.
I’m not an engineer but I am a tinkerer. Being a goldsmith for over 30 years I work with my hands from dawn to dusk daily. I also
tinker with vintage cars and tractors as well as bicycles and unicycles. I’m also busy working on my 115 yr old home And our families 125 year old log cabin. My rough stained hands are never idle and I wouldn’t want it any other way.
I don’t necessarily think this is about science, engineering or tinkering, some folk maybe just want to analyse their riding so they can get “better”. It is not even a case of doing it for competitive reasons or to the be “the best” – maybe they just want to get a new personal best and analysing their power output may reveal things like producing more power on one side than the other which they can address through technique.
Anecdotally at least (based on the fact that I seem to get quite a lot of email from various companies pushing power-meters nowadays) these things seem to be getting more popular in road cycling nowadays and certainly more affordable than they were. They are not just the realm of elite level cyclists any more. It will surely be a reasonably small subset of unicyclists who want to do this level of analysis (and can afford it) but if they want to get some insight from that surely that is a good thing for them and for pushing the boundaries of the sport.
There are a lot of unicycling disciplines and relatively few riders compared to bicycling and hence limited online presence; as a unicyclist looking at online content you are probably exposed to a more diverse range of disciplines than if you were to look at specific cycling forums. For example, I’ve never looked at any BMX or dirt-jump bike forums (I assume there are) so don’t know the levels people go to in those fields to “be the best” or just get better.
I think most of the street/trials/flatland folk moved over to Facebook a few years ago (maybe even skrrrt now) leaving primarily a different demographic here with muni/touring/road/distance etc. and that may mean that there is some more bias towards technical stuff – but then I don’t “do” Facebook so I don’t really know what happens there 
.
@unicycleharry This week I’m going to try out a friend’s road clipless pedals, to see if it’s time for me to switch from my SPD shoes to a pair of favora assioma road clipless pedals.
I’ve read that these pedals allow you to have lots of indicators such as Power Balance, Torque Effectiveness, Pedal Smothness… You could interpret these indicators with your pedals and check some hypothesis that seem quite logical such as: Is the torque effectivness less good in unicycle than in bike? Is pedal smothness worse on flat pedals than clipless pedals?
