1 minute: upright vs MetaBike power

Comparing power output on the MetaBike versus upright DF bike on a one minute max effort hill climb…

Following my recent PowerTap test of the RaptoBike Midracer / DF racer, I said I hadn’t bothered to record a maximal effort on both bikes because the figure would reflect a lot of inequalities:

  • how much have I been riding either type of bike?
  • are the tyres comparable?
  • how efficient are the particular drivetrains (is one chain dirty and the other clean?)
  • what’s going on with frame flex?
  • etc. etc.

However, more than one person in various forum discussions said I should record maximal uphill efforts on both platforms to provide some backdrop, despite the fact that it wouldn’t isolate a particular factor.

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Edinburgh’s Observatory Rd: short but sweet…

So, against my better judgement 😉 I ran a head-to-head between the MetaBike I had out on trial (known to be one of the stiffer and better climbing recumbents) and my all-steel commuter bike. I chose the commuter because the all-up weights of both bikes come very close – possibly the DF is a little heavier in fact…
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Powertap: convert watts to calories burned

Calculating calories (kcal) consumption for given wattages using a cycling power meter, such as a PowerTap.

Calculating a hard baseline for energy expenditure

PowerTap. After the immediate thrill of “how many watts can I do?” (answer: disappointingly few!), I moved on to the next most obvious question: “how fast will my bike(s) go for a given wattage?

However, there’s another side to measuring power output which I hadn’t really considered until some time after I built up my PowerTap. You actually know how much energy you put into the road over the course of a ride (or part of a ride).

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Turning watts into calories

If you know duration and average power you already have energy, it’s just not expressed in good old-fashioned calories. It turns out there’s a suprisingly simple formula to turn the wattage from a power meter into kcal though:

energy (kcal) = avg power (W) X duration (hours) X 3.6

As with so many surprisingly straightforward looking formulae, there are assumptions built into the constant.

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Power Test: RaptoBike Midracer

A 100W advantage? Testing the efficiency of the RaptoBike Midracer recumbent versus a drop-bar racing bike…

Measuring aerodynamics / rolling resistance

Not measuring drive losses or biomechanical efficiency

In this article I use (PowerTap hub measurements in loosely controlled outdoor conditions to provide an insight into the performance of the RaptoBike Lowracer. Please note: the test protocol is discussed frankly at the end of the article.

The Bikes

In the blue corner:

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My Planet X Superlight Team road bike, a pretty standard sort of roadie creation, weighing in at around 8kg with SRAM Rival. If I had a fitting, I suspect the bars would come back a little, as I’m quite stretched out (although that should favour the bike’s performance in these sorts of tests).

Tyres: Continental GP4000s rear, Vittoria Rubino Pro3 front

In the red corner:

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The RaptoBike Midracer, a FWD recumbent that is aimed towards the faster end of the all-round market (it’s not as much of a ‘racer’ on the recumbent spectrum as my DF is, for instance it can carry luggage). The Midracer weighs in at around 13kg.

Tyres: Continental Gatorskin 25mm rear, Continental GP4000s front

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