The Science Behind a Great Pedal Stroke

// Topics Covered In This Episode:
00:00 - Intro
14:43 - How power is produced through the pedal stroke
18:39 - The muscle used for producing power on the bike
23:23 - Torque effectiveness and the creation of an effective pedal stroke
28:16 - Synchronizing the top and bottom of your pedal stroke
// LINKS
Articles:
- Everything to Know About Pedaling to Maximize Your Cycling Power: www.bicycling.com/training/a2...
- Why and When to Use Low-Cadence Intervals in Cycling Training: www.trainingpeaks.com/blog/lo...
- Cycling Cadence: How Fast Should You Pedal for Ideal Performance: www.bicycling.com/health-nutr...
Research:
- Influence of duty cycle on the time course of muscle fatigue and the onset of neuromuscular compensation during exhaustive dynamic isolated limb exercise: www.ncbi.nlm.nih.gov/pmc/arti...
- Optimal cadence selection during cycling : review article | International SportMed Journal: journals.co.za/doi/abs/10.105...
// GUEST
Charlie Livermore first worked in Pro Cycling in 1989 with the Wheaties-Schwinn Cycling Team. Then he worked with Chris Carmichael at USA Cycling before spending three years with the Coors Lite Cycling Team, and finally seven years at the helm of the Volvo/Cannondale Pro MTB Team. In 2004, Charlie founded and operated a cycling performance center in Northern California. In 2006 he co-founded Continuum Sports, the management company of the BMC Pro Cycling Team. He joined CTS as a coach in 2011.
// HOST
Adam Pulford has been a CTS Coach for more than 14 years and holds a B.S. in Exercise Physiology. He's participated in and coached hundreds of athletes for endurance events all around the world.
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[@mattsmallshot]

as a motorcycle mechanic, this sounds like a inline twin 2 stroke engine, something to get in my mind when riding my bicycle now

[@Velodictorian]

This totally explains the effect of too long of a crank that I was feeling. With 175s (I’m 5’7”), I always felt it difficult to get stroke started and started at 1230 or 1 instead of 11 that I can do with 165s. I also feel like I’m able to extend the stroke deeper into the 7 o’clock position. My circle is more circular instead of eccentric

[@awalling1]

Worked on this for the last month ,. Definitely focusing better trying in synchro 11-1, 5-7 . I Improved power and cadence +++ . Thanks soo much…

[@mariafernandapinzon843]

Charlie Charlie !!! You are the best thank you for all your advise always pedaling. Thank you Adam for inviting him. You both are a great team !!

[@kennethderrington1229]

Great presentation. Charlie I still remember how you helped me with cadence and pedal stroke 11 years ago climbing Squaw Pass on our way to Mt. Evans. Thanks again, I'm still learning and improving. Ken

[@silviapeterson1856]

Brother Charlie! How great to see you on your first Podcast in your zone of genius. You are a natural and a wealth of knowledge! ❤

[@rayF4rio]

My imagery is to to think of the crank/BB as a pepper mill (with the old little hand crank on top) and to think about grinding pepper with my legs. Been doing this since the 1990's and now its just natural. In fact I've had other cyclists ask how I've developed big hamstrings for cycling.

[@billmccaffrey1977]

As a BKA (below knee amputation) of one side), this explains the lose of symmetrical force balance, which is not huge. The lose of dorsiflexion on one side is more significant. The prosthetic binds the area behind the knee causing you to need to bring that knee higher and thus can over extend the opposite leg. I have reduced my crank length to 165mm. I have learned to cycle at higher cadence 90 to 110 and use low cadence 50-60 to build strength. I would love to improve my efficiency even more.

[@vantarpon6849]

I switched to 165mm cranks to address my hip arthritis/hip angle. Even at 6"2" , going from 175mm to 165mm was seamless and felt natural. Getting back on 175mm now feels strange. Good job on finding improvement with your situation.

[@ChrisAcheson]

Adding pedal upstroke power is key.

[@davidbee9563]

I ride a fixed gear commuting bike year round with a low gear(38/16) in an area that is mostly flat bur some short climbs. What I find is you can learn to pedal efficiently at various speed/cadence and load/effort. Going downhill or with a tail wind to keep pedalling smooth, under control. And then uphill or into the wind smooth application of power at lower cadence. To be smooth at 60, 80, 100 and 120+ cadence. There is a short sequence of rolling hills on the edge of the city. Speed is 10 to 15km/h at the tops and 40 to 50km/h at the bottom. My fastest segment time is still on a fixed vs a geared bike. I am 185cm tall and ride with 175mm cranks on all my bikes. I have found with shorter cranks on road it does not feel like I am using the entire range of leg muscles. But on track I ride 170 cranks with a 46/16 and it feels OK, mostly riding 28 to 35km/h. Looking forward to part 2.

[@emmabird9745]

Hi Guys, this is very interesting. I've been riding for nearly 60 years so i have some bad habits. I've tried making my strokes "back and forth" like you appear to be saying, 11 o'clock to 1 o'clock and 5 to 7 but its never felt right. Recently I've been pulling the upstroke, thats the areas 5 and 6 in your first slide by concentrating on lifting the rear leg only and letting the front leg do its own thing and my trainning loop times have tumbled, I'm going about 10% faster. My reasonning is that instead of the negative torque (the red bit on your torque graph) I'm now producing positive torque there (turn red to blue). By practice over about a month I can easily keep this up for more than 30 minutes. I am now trying 0.5kg ankle weights and feel as though those muscles are getting stronger (I'm even faster when I leave them off). Am I doing wrong? Is my back and forth techniqe simply needing more exercise and give up on the lifting up or even can I combine both? Any views?

[@salmar1634]

Great presentation! My question is if my indoor bike on a smart trainer has 172.5 cranks and my outdoor bike has 170, is this a bad thing or a long term issue. I typically ride out on weekends and 3 rides during the workweek.

[@gerrysecure5874]

Don't worry, unless you have a medical limitation you won't feel nothing. I once bought a left side 175mm PM for my (winter) MTB and in summer I mounted it on the roadbike which had 172.5 mm on the chainside. I noticed after several years by accident when I cleaned the bike. People make a fuss about mm forgetting we are inherently asymmetric biological entities not precision machines.

[@vantarpon6849]

@@gerrysecure5874 Well said regarding asymmetries. Same can be said about obsessing about L/R leg power distribution.

[@racittaj]

The problem is that first you need: 1. Ideal crank length for your body and discipline/position(road, tt, gravel, xc..) 2. Perfect q factor/stance width 4. Perfect cleat position, shoes and insoles. 3. Perfect symmetry L/R. Shims/wedges, different crank length L/R- nobody have perfect symmerty by default! One you get all this correct than you can start..

[@larrysemer1582]

A lot of this seems to depend on saddle height

[@edwarding4355]

Shorter cranks seem to follow this logic.

[@argeelearner3978]

Can you address crank length inyou need podcast?

[@topcat304]

In studying physics and physics in sports, we sometimes get terms confused. In terms of Power, I think we need to are talk about 'Work' ; W=F x Distance. This is the same for the length of the push by a speed skater on ice or the force on the pedal by a cyclist. Time of application is important. The same force applied over a longer period = more 'Work' being done and faster speed. ( im only referring to the time of application to the pedal, not the distance the body part travels)

[@neoneherefrom5836]

I’m not exactly sure what you’re trying to say but I’m pretty sure there’s a simpler way of saying it. Lol

[@topcat304]

​@@neoneherefrom5836You are probably right. Just start your push at 11:30 instead of 2:30. This like other techniques needs to be practiced when you are fatigued as well.

[@neoneherefrom5836]

@@topcat304 begin momentum a little earlier than necessary prior to the optimal force requirement phases of the pedal cycle to ensure continuity stroke over stroke!

[@topcat304]

@@neoneherefrom5836 I guess we could use the old saying "If your not early, you're late!"

[@neoneherefrom5836]

@@topcat304 BINGO!!!! just like you’d be a damned fool to go into the base of a small hill with minimal momentum and suboptimal gearing when doing otherwise could very well do half the work for you depending on the size of the hill. Ain’t science a beautiful thing when it’s applied to a sport you love. ;)

[@gerrysecure5874]

Optimal cadence depends on duration of the effort. Sprint 130, 5min 70, 20 min 80, 2 hrs 90 so its a U shape. Max power needs high cadence due to strength limit, vo2mx needs low cadence due to cardiac limit , long duration high cadence again due to muscle fatigue. Science sometimes is just unnecessarily dumb in complicating things. Edit: Thanks for feedback guys. Just keep in mind the numbers are rough averages to illustrate. Your individual optimum may be bit higher or lower depending on your training history, but you get the idea. When it feels right it probably is.

[@bitchoflivingblah]

clear and concise. thanks.

[@salmar1634]

Wow! That's exactly what I needed to know, cadence according to type of indoor workout. Always wondering if I'm doing my Vo2 and thresholds correctly.

[@Gabrielle4870]

Scientific data to back this proposition?

[@neoneherefrom5836]

When it feels right it probably is… until it doesn’t … and it isn’t… Thresholds can come without warning and can be masked by analgesic effects.

[@gerrysecure5874]

@@Gabrielle4870 Brain and experience.

[@tan240sx]

Why does the diagram at 28:05 show peak torque being at 3 o'clock? That's about where I start applying power and I peak at just before 6 o'clock. Seems counterintuitive.

[@WanderingSword]

diagram is correct. Peak torque is at 3 oclock, not 6. Reason is at 3 oclock is where you apply most leverage to the crankarms

[@gerrysecure5874]

Your rotation speed may be near max at 6 o'clock, but your torque approaches zero.

[@speedy81]

Great show and presentation. Does crank arm length affect how smooth is one's pedal stroke? I'm 5foot 3, not tall, fairly flexible and don't have any major hip impingement. I have been using 170mm cranks for the last 3years but just started trying out 165mm cranks. Still getting used to the shorter crank arm and i do feel my pedal stroke is smoother but feel it's more effort when using bigger chainrings. I missed the leverage from 170mm crank arms? Is this just a matter of giving my body time to adapt to the shorter crank arm ?

[@tomrecane6366]

Rollers. It’s almost impossible to ride them without a smooth cadence as described in this video.

[@stevedrake6529]

That guy says you know way too much!

[@edsassler]

Painful to listen to… First there is the difference between feeling and measuring. I built an adjustable bike that is plate loaded (it lifts plates instead of turning a wheel) to isolate forces produced - that’s my static measurement. What a rider feels is feedback from muscles. A tiny muscle working at its limit will feed back the same information as a large muscle working at its limit, but produce almost no force. That’s why people think they are generating force by pulling up on the pedal. Trying to teach a rider to pedal better by feel can’t work. Try engineering a pedal stroke based on the geometry of the body and its large muscle groups - glutes & quads. Quads extend the pedal from the knee, which is only effective from 11:00 to 2:00 (you actually got that one right). With the range isolated you then have to look at mechanical advantage. The attachment point of the connective tissue from the quad is very close to the pivot, it’s designed for foot speed in running. If you teach a rider to isolate just the quad by having them clip in with just one foot and accelerate the pedal from 11 to 2 over and over until that range becomes second nature, you can then start testing for effective cadence. Quads don’t like to produce torque, much below 80 RPM and the heart rate goes up without a corresponding change in power. Using hamstrings to pull back on the opposing range doesn’t work. Try getting the hamstring to keep up at 80 cycles/second - not gonna happen. Teaching a rider to isolate their glutes is easy, but It goes against their primary skill set - lifting their body weight. The basis for walking/running/standing is lifting your body weight. It involves firing the quad and extending from the knee. It’s your most used skill. When you sit on a bike and think about pushing down with the pedal at 3:00, your brain says “we know how to do that” and it fires the quad. From that position, extending the lower leg from the knee pushes the pedal forward. I have a simple way to teach isolating glutes, it’s called sitting. When you sit on a chair with your feet on the ground and lean forward, weight transfer is to the floor via the glutes. My point in all of this is that you’re not critical enough about how riders are pedaling, you lack a means of measuring, and you haven’t really figured out the engineering.

[@Gabrielle4870]

Learn to ride the rollers, fixed, free wheel, two legs, one leg. It'll be very obvious when / where you aren't smooth.

[@MrTeff999]

Eliminate P-minus and gain free power. IMO

[@paterjan9733]

The first and most important optimization is the body. This accounts for at least 90% of the performance. And you can't buy that with money. Getting your body into good shape is hard work over many years. And you learn everything about how to pedal and sit correctly through experience. Everything else is nonsense.

[@stephendenagy3396]

There is some truth in what you say, because the whole body generates power. As a physician, I recommend bicycling for developing core strength. But, for athletes, and aging individuals with bad knees (as myself), the mechanical aspects they discuss are CRITICAL. They are discussing efficiency, but poor duty cycle will lead to knee pain as well as being inefficient. What they didn’t really mention is that with bad ergonomics really, really strong people can be effective, perhaps later at the expense of joints, and loss of theoretical performance. This actually is very good stuff.

[@The123fiona]

Id be a bit more impressed id they could spell the word "pedal" correctly.