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issue 160
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A Survey of Power Meters Discussing Single-leg vs. Dual-Leg
The landscape of power meters is bumpy, but can be put into one of two categories. Find out which is right for you. Words By Rick Schultz, BAT DoC
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power meter is generally defined as a tool that measures the power you are producing while riding a bike, via strain gauges coupled with other electronics. Essentially, as you pedal, you are applying a torque along the drive-train. This torque bends or deflects components such as crank-arms, crank spider, crank spindle, pedals and rear hub. Power meter companies place strain gauges on their chosen component and measure the force you are applying. This force is then calculated against how fast you are pedaling to compute the number of watts you are producing.
ONE IS FINE, TWO can be divine
(180w x 2). This value overstates the riders’ power, and when coupled with a training program calibrated against this inflated value, over-training would occur. On the other side of things, if the measurement is taken of the non-dominant leg, it will understate the riders power. Training plans using the deflated value would lead to a lack of improvement due to under-training. Because there is no way to know the differential between your dominant and non-dominant legs without measuring each individually, using a single-leg power meter would lead to training using wrong numbers and leaving you not getting the gains you are working so hard for. A dual-sided power meter solves this issue by showing you the leg imbalance. In addition, the two-leg solution serves as a tool to train towards more equalized power output between legs, the ideal in terms of efficiency and fit.
Power meters can be segmented into two types, single-sided and dual-sided. This can also be considered single-leg or dualleg. I would typically recommend dualsided power meters over single-sided. Most riders I fit initially show a 60%/40% imbalance between legs, typically in favor of their dominant leg. And, herein lies the Side profile of a PowerTap P2 pedal that integrates the problem with single sided power meters. technology needed to measure power in the
Single Leg Failings
Let’s say our hypothetical rider produces exactly 300 watts average power. Factoring the previous example of a 60% - 40% discrepancy between the output of the legs, we can infer the dominant leg produces 180w and the non-dominant leg, a reduced outputs of 120w. If our rider were to use a single-leg power meter, whichever leg is being measured would be multiplied by 2 and displayed as the power output. This can be problematic. If the measurement were being taken at the dominant leg, our hypothetical rider would show a value of 360 watts
pedal itself. Pedal-based power meters provide the ideal, dual-sided measuring allowing for more accurate measurements.
Edge Case
Though dual-sided pedal-based power meters are a great option for many riders, I do not recommend them for criterium races. The components in the sensing pedals typically increase the pedal stance or make the pedal ‘thicker’. Both scenarios increase the chance of clipping the pedal on the ground when pedaling through a corner. For the rest of us, pedal-type dual-sided power meters will work well for your training goals.
Coach Rick Schultz specializes in coaching riders so that they can achieve their best. He is a certified bike fitter, and the official BICYCLIST Adventure Team (BAT) Director of Coaching (DoC). Send your questions to coach@bicyclist.xyz SoCal Local? Make an appointment for coaching and bike fits. 6 | BICYCLIST Issue 160
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Column 4 Construction 16148 Sand Canyon Ave Irvine, CA 92618 Lic: #992770 www.column4co.com
(949) 420-1601 Serving SoCal and beyond, for more than 25 years.
Back to School, Back to Work
All Grey? With Integrated reflectivity, all the way
Consider improving your commuting experience with some of the latest iterations and designs to make the most of your time in the saddle. By the BICYCLIST Adventure Team
PROVISIONS
With summer vacations behind, school and college back in session, no better time to incorporate a new component to your daily routine - commuting by bike. It doesn’t need to be a gear intensive endeavor, but we’ve found the ride is a whole lot more manageable, safer and sustainable with a bit of comfort and surety added to your pedal-powered routine.
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EVIL MINI | Road Runner Bags,www.roadrunnerbags.us ($110) JETLAG NERO | DZR shoes, www.dzrshoes.com ($99) AWA BLACK ‘Drizzle’ Shirt | Dainese, www.dainese.com ($120) AWA BLACK ‘Ombre-Blue’ Trousers | Dainese, www.dainese.com ($165) FORMULA LED MIPS GHOST | Bell Helmet, www.bellhelmets.com ($125) LED 360 Canopus & Vega Light Set | PROVIZ, www.provizsports.com ($80) TOUR RACK | Thule, www.thule.com ($115)
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BICYCLIST Issue 160 | 7
FIRST LOOK
Climb With Me s a ge Tita nium Bic ycl es ‘fl o w mo tion’ a Titanium Hardtail brewed in Oregon is ready for racing, ripping or just rolling steadfast. Words and photos by Chris Reynolds
Bike demo courtesy Revolution Bikes, Solano Beach
The Sage ‘Flow Motion’ offers the comfort and dynamism of titanium tubing, while skipping the extra weight and lost pedal efficiency of a comparable full-suspension. With the versatility of Boost axle spacing, the domestic frame allows up to 2.7 x27.5 plus or 2.2x29 tires, and geometry suitable for most any mountain enthusiast, no matter the terrain.
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T
h e experience of mountain biking includes climbing unrelenting grades, descending washed out trails, muddy runs and general trail nonsense. That’s kind of the point. If you wanted smooth roads, you’d be on a road bike. To accentuate the experience, Sage Titanium Bicycles recently released the ‘Flow Motion’, their made in USA solution to the variety of trail most riders encounter. The titanium hardtail frameset accommodates either 2.7x27.5+ or 22.2x29 wheel sizes, features wide ‘Boost-spec’ axle spacing, and integrated dropper-post routing, all wrapped up in a frame geometry that allows for efficient climbing and stable, comfortable descending. Speaking with David Rosen, the owner at Sage, the idea for the Flow Motion was a hard-tail that featured the long reach and slack angles coming out of frame shops in the UK, while addressing the diminished climbing abilities reviews had levied against those same designs. The benefits to descending are improved by increased angles of the front fork relative to the axis of steering, but there is a diminishing return to this calculation, and without mitigating the downsides of this design, the hindrance to climbing is pronounced. Rosen’s solution was to shorten the chainstays, utilize a bent seat tube and increase the angle on the seat-stays to shift the riders weight rearward. This positioning allows for more traction of the rear-wheel with loose dirt and better power transfer when climbing, especially on steep grades where you will want it most. The frame includes modern standards like routing for a dropper-post, single front chainring and disc brakes. Staying with tradition is the use of a 68mm English bottom bracket. The benefits of a larger sized ‘pedal bearing’ are moot when ensconced in the ridged bosom of titanium, and a more standardized bottom bracket ensures an adapter-free experience. And to be expected of a bike of this caliber, the overall quality of the frame itself is superb. (Frame $3,400 / As Built $7,861) www.sagetitanium.com
The wide stance of the RaceFace Atlas bars offer control and confidence while piloting the versatile hardtail. Though the front-end is quite slack, the wide bars offset any expected ‘mush’- steering is nimble and quick.
The oversized 44mm head tube offers considerable stiffness to the front-end. Meticulous dime-stacked welds set the stage for premium craftsmanship found throughout the titanium frame. Usability and rider-experience were thoughtfully considered- the result? A do-it-all mountain shredder.
Hardened titanium tubing imported from Dedacciai, the storied Italian tubing supplier, provide the basis for shorter-length chain-stays. This shorter length puts the rider further aft, keeping weight over the rear tire when climbing, critical for maintaining traction on a hardtail frame.
A side profile highlights the ‘Flow Motion’ geometry, just under 66 degrees of head angle keeps things comfy on descents, whilst the curved seat tube and shorter chain-stays keeps rider weight over the rear tire, helpful when climbing.
The Boost-sized chain-stays provide clearance for 2.6 x 27.5+ or 2.2 x 29inch tires- the versatility and compatibility of the design allows for any manner of wheel size preferences.
BICYCLIST Issue 160 | 15