B. Riepe Blog: Back on the Program with a new SRM Power Meter Crank

Training at the mercy of a mindless computer

The new SRM power meter crank showed up at my house in mid July and sat on my dining room table for some time; the shiny black FSA carbon crank arms with their red and white racing stripes glistening under the lights like a sports car possessed. Each time I walked past I could here the call: “Go faster, faster, faster…”

It’s been over 9 years since I’ve even strapped on a heart rate monitor and I haven’t missed spending the torturous hours on the bike, legs ticking off a high cadence near my pain threshold and eyes glued to the antagonistic numbers on my wrist watch telling me I’m slacking off of the pace, letting my heart rate drop out of whatever target zone I’m supposed to be in for the ride. I thought those days were over for me.

Not to say I don’t enjoy hammering out a fast ride these days but rather, I like to let my mind and body decide when it wants to go hard and for how long. It generally works out good enough for me. My friend Greg Frozely at SRM calls it the masters workout and many of us working, racing, 40 plus parents know it well: you have and hour and a half at lunch or after work to ride, so you leave the door at race pace, go as hard as you can for most of the ride, take a 5 minute cool down riding through your neighborhood, pull into your house satisfied and dive back into more work or family time.

It works—I can still hang at the occasional race—but Greg, taking a job at SRM, has sold his soul to the devil of highly managed, targeted training again and he’s trying to pull me back into it with the lure of more power via better quality masters training sessions—measured, graphed, and controlled by these SRM power meter cranks.

The cranks kept calling at me so I finally dove into the installation process, thus beginning my return to The Program. After some mildly frustrating moments in the shop trying to figure out why the crank spindle wouldn’t fit into the supposedly compatible bottom bracket on my Trek EX 9, I finally called The Trek Store in Boulder. I was told to ‘just use a rubber mallet to hammer it through the bearing cups’. Hmmm, well, of course, always resort to using force on finely crafted carbon fiber components (shutter). But it worked. Not sure how I’ll get them out.

Setting up the cadence sensor was relatively painless (see image below) and the getting the computer mounted and set was okay: the computer is rather large and the mounting bracket is designed more for road bars so the computer sticks out farther than I’d like and will likely break off if I crash. Programming the unit was typical: setting multiple functions using only three buttons but eventually I had everything (except the wheel size) calibrated and ready to ride.

The SRM crank is made in Germany and is, as expected, a beautifully engineered piece of equipment that measures, in watts, ones power output coming into the cranks. The complete setup allows a rider test their output in watts, speed, crank cadence, and heart rate—giving me more info than I’d ever had during a training program. The unit hardly adds any weight to a bike but adds plenty of cost.

SRM cranks are more commonly used on road bikes but I chose to take my suffering with a small helping of dirt to add a little fun into my upcoming suffer sessions. My first ride was rather successful (except that I didn’t have time to calibrate my wheel size into the computer so my speed reading was incorrect) and I can almost say I enjoyed it.

With the computer hanging in front of me, nagging at me, egging me on, I have to say it was the hardest ride I’ve done all summer and it became glaringly obvious the, left to my own devices I will slack off when I can. Having the cadence and output numbers dancing in front of me on each climb kept me honest and working hard. For obvious reasons, the SRM is a great training tool and I’m looking forward to having more focused workouts.

The long term plan is to set up a six week program with Daniel Matheny—an expert coach at Carmichael Training Systems in Colorado Springs—and, using the SRM, see if I can improve my watts and endurance on the bike in time to make a decent showing at the 25 Hours in Frog Hollow race in early November.

More tales of pain, suffering, and hopefully success to come.—B. Riepe

Setting up the SRM crank on Trek EX 9 was easy - once I learned using a mallet was fair game. The SRM power meter i housed within the chainrings and mounted to a sweet FSA crank with nearly no weight gain.	Speed is one factor measured with the SRM computer. The sensro mounted painlessly to the fork.	The SRM computer mount has limited options, seemingly designed w/o mountain bikes in mind. I tried to mount it sideways on the stem but it would quite work without modifying it. Ideally I'd like to see it mounted low and safe behind the bar, next to the stem or on top of the stem. As is, one good crash will knock this off the bike.
Mounting the cadence sensor on the carbon Trek EX 9 frame only took minor mods (cutting away a small piece of the chain guard. I used stick velcro for now but I'll glue on now that I know it's working.