CompuTrainer SpinScan radness!
Today I lived one of my nerdy dreams. I went to the Boulder Center for Sports Medicine, hooked my Tricross to a CompuTrainer-equipped trainer and got my pedaling stroke analyzed with SpinScan software.
This experience confirmed some things I was feeling, and it blew one notion out of the water.
Who and where
The Cave at the Boulder Center for Sports Medicine.
Lester Pardoe, Boulder Center for Sports Medicine coaching specialist and biomechanical technician, dialed me in at the Center’s “Cave,” which is short for Cave of Pain.
In this small room, eight trainers are tied to the CompuTrainer system. The specialists can do in-depth analysis on a single rider, or they can subject up to eight riders to indoor cycling brutality. I did some of those classes a couple winters ago, and they were awesome. The system sets the resistance for your weight, your power level and the workout protocol. All stats are displayed on a big screen. If I did this class with some of my buddies, an ambulance would be on call.
Sissy excuse: I rode from home to the gym, did a very hard workout, then rode to the Center. My legs were blown when I got there.
How it works
CompuTrainer and SpinScan are powerful programs, and I’m sure I barely scratched their surfaces. To begin, Lester hooked me up and got me spinning. An oblong graph appeared on the screen, signifying the efficiency of my pedal stroke.
A narrow figure eight means terrible stroke mechanics. The rounder the shape, the rounder the stroke.
The screen also showed:
– Current power in watts.
– Current cadence.
– Percentage of power generated by left and right leg. 50/50 is ideal.
– Average Torque Angle (ATA). That’s the average point on the circle where most of your power is applied. A perfect score would be 90 degrees from vertical, or 3 o’clock.
– SpinScan. This number, 0 to 100, signifies the efficiency — the roundness – of your stroke. A score of 100 would mean you’re applying force evenly all the way around the circle, which is impossible. Lester sees SpinScans below 30. The best SpinScan he’s ever recorded was 90, by world champion XC racer Gunn-Rita Dahle (that’s her demonstrating pedaling technique in MMBSii). 75-80 is considered very good.
Lester said I have good technique and power, but, if I want to sustain that power longer, I need to do more long rides. Can I get a doctor’s note?
My scores when I just sit, relax and spin.
Power – About 225 watts
Cadence – About 90 rpm
Left/right balance – 50/50
ATA – About 100 degrees, or 3:30
SpinScan – 67
Concentrating on good form
This system is incredible. As you make subtle adjustments to your pedaling style, you can immediately see changes in your stroke shape and power.
Power – I wasn’t paying attention.
Cadence – I was most efficient around 90 rpm.
ATA – When I focused on pushing across the top of the stroke, I could get close to the ideal 90 degrees. But only as long as I focused.
SpinScan – If I focus on pushing across the top of the stroke, I can average about 75. At one point I hit 80, but I have no idea how.
I love to climb out of the saddle. It just feels good, and I think I have great technique.
When I stood, my SpinScan dropped from 75 to 55. Yikes. When I focused on perfect form … 55. When I tried a really hard gear at low rpm, like when I climb home, 55. Dang.
Lester says you can certainly make more power out of the saddle, but it’s less efficient than sitting.
Trying to turn that peanut into an egg.
Things that work
The only way I could consistently improve my SpinScan was to focus on pushing across the top of the stroke. For me, that is the A-1 key. I’ve been working on this all year, and I will continue.
Everything feels (and measures) better at 90-100 rpm. When upshifted and dropped to 60 rpm or lower, my numbers dropped and my already blown legs got heavy and dumb.
Thing that doesn’t work
My lowest SpinScan happened when I focused on pulling up on the upstroke.
At high rpm you can’t pull up; the pedal is moving too fast. I slowed my cadence then focused on pulling up.
I pulled so hard that I could hear my cleats clack in the pedals, and I could feel my feet stretching my shoes’ uppers. And … my SpinScan dropped from 77 to … 45.
I was feeling awkward and working way harder, and my stoke got worse.
We worked the SpinScan for quite a while, then Lester set me up for some quick power tests. I knew I was beat, but my home trainer maxes at 999 watts, and I was curious.
Peak power: 1,200 watts. This is pretty good but not extraordinary. I want to work on that one.
We also did this rolling-start power test where the rider covers a certain distance as fast as possible. The mens’ record is 20 seconds. I rolled a 23. My peak power was great, then I petered out. I can do better.
I want to do more detailed work on my own stroke, but the research potential is enormous.
Flats vs. clips: Yeah baby, it’s on! Lester said he’s help me test flat vs. clip-in pedals. We’ve all heard the theories and arguments; I want to generate some meaningful data.
Offer this service to my skills clients: I’ve asked how I can get my clients in for this pro treatment. After all, pedaling is a skill, and to pedal better is to ride better.
Power! I want to do a real-deal power test. Like I need more things to obsess over.
After an hour-long gym workout and almost three hours riding at the Center, I rolled the Tricross up Sunshine Canyon to my house. My legs (and whole body) were blown. I just kept it in my 34×28 and focused on pushing across the top of the stroke. Not going fast, not trying to do anything great, just focusing on comfort and efficiency.
And … I reached the top of the climb a full minute faster than ever before. Crazy.
It’s all about pushing across the top of the stroke.
Indoor computerized braaap!
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I hear flat pedals force you to push across the top of the stroke.
What about seated versus standing on a DH bike? For instance, long flat mellow section where you are already up to speed. Is it more powerful to be seated, pedaling with a low seat or standing?
Chris Q: Yeah man, you know it! Do good high-rpm strokes with flats and clips will have similar efficiency and power? We’ll soon find out.
Christian: When I raced at Northstar (your spot), in those transitional sections I used to sit and pedal from the back of the saddle. That felt like a good way to maintain speed while recovering for the next batch of gnarl. Another thing to test!
Super excited to race the Boulder Cup cyclocross this Sunday!!!
Great post! Very interesting.
Perfectly timed too as I have a 110k/66m hilly road randonee this weekend that I am doing on my MTB (flats and slicks). I’ll concentrate on pushing across the top of the stroke.
Tomorrow and Friday I am coaching riders on trails with flat pedals. We too will be pushing across the top.
Awesome data! This is why I always check your site Lee- these little nuggets of cycling wisdom. More! More! Now take your BMX bike next time and see how that turns out.
How about testing various crank lengths?
Great info! Keep the data coming.
I love having new things to work on while riding. Higher rpms, pushing across the top…
Big long hill near my home that I climb for the exercise. This summer I read something somewhere and tried pushing over the top of the pedals during the climb. Huge difference. I was surprised at the extra speed I picked up.
Update in case anyone but me cares:
At the last sprint test I increased my max power from 1,200 to 1,300 watts.
Today I knocked the .2-mile power test from 23 to 25.5 seconds. 970 watts max, 740 average.
I’m trying to make sure I understand what they’re testing, as I’m not sure I concur. The way I see it, depending upon the situation, you want to maximize (a) efficiency and (b) power.
Efficiency: I would rate that as minimum muscle fatigue per power. I would say minimum heart rate, but that comes from bogging down and having lower cadence, which isn’t good for long term efficiency. Now, pedal smoothness helps, but if you can put more power at the downstroke than you can at 12/6, why is that bad?
When you were pulling up, you are increasing the power output at the 3/9 position, so of course your SpinScan number goes down. I can’t say that’s a bad thing.
Power: Averaged over the entire pedal stroke. I think the .2 mile test is a good judge of that.
Want to really impress me though? CompuTrainer Bunny Hops 🙂
I’m not sure either. I was reading the CompuTrainer software manual last night (yeah, rad!), and that SpinScan number is indeed about efficiency. As someone who does a lot of climbing with a so-so engine, I want to be as comfortable and efficient as possible. But I’m not sure how that important that efficiency number is to all-out power.
In Coach G’s tests with elite BMXers, he finds the most powerful sprints are not necessarily “efficient” in the SpinScan sense.
I’m stoked to be thinking and talking about this stuff. More study is needed!
BTW: The other day I improved my PR in the .2-mile test by a second. Peak wattage: 970; average wattage: 740. When I was pounding my way to 970, I was NOT pedaling daintily like a fairy princess!
I read (somewhere on the internet, so it must be true) that mountain bikers do indeed have the smoothest pedal stroke, because traction control requires minimizing the variation in the load over the pedal stroke.
SpinScan number is about smoothness, I think. 100 means the torque torque for the entire pedal stroke is constant. Is that right? That would explain why the number goes up when going over the top (increasing your 12/6 performance closer to your 3/9 performance) and goes down when you pull up (increases the delta between your 3/9 performance and your 12/6 performance)
For kicks, try this: reduce your downstroke force. That is, soft pedal through the 3 o’clock position. Dollars to donuts that you will increase your SpinScan number. That said, I’m not sure I agree that you will have a better climbing efficiency by doing that.
Congrats on the PR! Rock on!
Lester at the Center says the same thing, that MTBers tend to have smoother strokes than roadies.
Yes, a SpinScan of 100 would mean steady pressure around the entire stroke.
Olympic and world champion Gunn-Rita Dahle (featured in MMBSii) scored a 90. Lester says that’s the highest he’s seen.
Lester says a super-high SpinScan isn’t necessarily better. The power phase of the stroke should be more powerful.
My feeling and theory: Pushing across the top keeps me more engaged with the pedals and starts my downstroke sooner. The downstroke then takes care of itself.
I wish I could study this stuff in crazy detail, but the system, without the PC or bike, costs $2k!
I’m a new mountain biker (started mountain biking about 4 months ago). Bought your book Mastering Mountain Bike Skills 2nd Edition from Amazon about 2 months back and the book has really helped my riding a lot. Have read it cover to cover and re-read specific sections often. Good job!
And I have now started to check out this website of yours.
I would love to join your clinics, but unfortunately I live in Kuala Lumpur, Malaysia.
I just want to clarify what you mean by ‘pushing across the top of the stroke’. You mean pushing each pedal as it approaches the 12 o’clock position right?
Thanks for the clarificatin.
Wong, welcome to the MTB world.
Yes, you are correct. The earlier you can start the power phase of the stroke, the better.