I've been talking a lot about power numbers lately. It occurs to me that there are those in my vast readership who might not know anything about power as relates to cycling. I'm here to help.
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| No, not that kind of force |
Simplistically, power is a measure of how much force you're putting into the pedals and is expressed in watts - just like a light bulb. In electrical terms, a watt is a derived unit of 1 joule per second. A joule is the energy transferred to an object when a force of one Newton acts on an object in its direction of motion through a distance of one meter (one Newton meter).
OK, enough with the technical stuff, what's that got to do with cycling and how is it relevant to me? As I said, watts is an objective measure of how much power you're applying to the pedals i.e., how hard you're working. Nowadays, this is measured via a power meter (well, duh) which come in a variety of forms: pedal based, integrated into the spider of the crankset, or a specially built rear hub. The thing all of these have in common is a "strain gauge" that measures force in a standard way. It's generally true that the closer you get to the source of the power (you!) the more accurate the measurement so pedals are the most accurate and a hub is the least since you have drivetrain loss. Probably the least accurate is a hub based power meter on a long wheel base recumbent like a Bacchetta. The drivetrain loss in an LWB recumbent is on the order of 20%. As I've said previously, I have all three types and they're all accurate enough for my purposes.
Back in the day before power meters, people still spoke about how many watts a rider was generating. Given the weight of bike + rider, a hill of known gradient and a fixed distance it's a relatively simple calculation to get a pretty accurate estimate of the amount of power a rider is producing. Dr. Miguel Ferrari (of "Operation Puerto" fame) used to take his clients to a particular hill with a stopwatch. Pro riders in the Merckx/Indurain era didn't have power meters on their bikes when they raced but sportswriters used to time them on climbs during races and print estimates of how much power they were putting out, usually using phrases like "super human", "other worldly" which meant "doped to the gills".
Nowadays, every professional rider has a power meter of some sort, usually crank based, on their bike and many of them post power profiles on Strava. The data is also quite often displayed in real time during the race. Modern racing bikes are so light that weight needs to be added for them to reach the UCI weight limit of 6.9 Kg so a power meter serves the dual purpose of bringing the bike up to the weight minimum and providing useful data.
Pro riders put out insane amounts of power. We could have a lively discussion on the methods they use to achieve it but the results are impressive regardless. A top sprinter will turn over a 53x11 gear at 125 RPM producing in excess of 1500 watts. A climber making a break will put out 700 watts or more for 10-15 minutes and your "average" pro rider can crank out 400 watts for hours.
And then there's me.
Regular readers will know I've had back trouble on the bike since 2014. The back plays a significant role in producing power, it's the fulcrum that allows you to use your upper body to counterbalance the force generated by your lower body. That's why core strengthening is so beneficial to cyclists, it stabilizes your upper body and allows you to generate more power.
Despite my chronic back ailments I used to be able to generate a reasonable amount of power with an FTP of just over 400 watts. This decreased significantly over the past two years as my back became increasingly worse to the point where the last 20 minute FTP test I did (in 2019) I only managed an FTP of a little over 260 watts.
Although there are a number of training programs under the general heading of "FTP builder" I never used any of them instead adopting the Merckx philosophy of "ride lots". I'd periodically push as hard as I could on climbs or keep my average speed above some threshold for an interval, go for a KOM, things like that. That worked well enough and I was able to produce a reasonable amount of power up to the limit my back would handle.
Post surgery I've been monitoring my power output carefully as noted by the most recent posts. I've seen improvement and hope this continues. I've found that at this point my back is able to handle a sustained hard effort better than the semi-maximal load created by a sprint. I've found this out "the hard way" so I'm staying away from sprints and am focusing more on "keep the watts above x for y minutes" sorts of efforts. I do hope to introduce short, hard efforts at some point, most likely in the spring when I've rebuilt a base of strength.
Stay tuned!
