Pedals or cranks, one leg or both, and whether you need a bicycle power meter at all.
A power meter changes how you train more than any other upgrade. It is also the one people most often buy in the wrong format, because the marketing is all about accuracy and nobody mentions the practical side: how many bikes you ride, which pedals you are attached to, and who is going to fit it.
This is how we help people choose when they ask us in the shop.
Do you need one?
If you ride for fun, commute and never follow a structured session, a power meter will not make you faster. Better tyres or a bike fit will do more for you.
It earns its money when you do something with the number: intervals to a target, pacing a sportive so you do not fall apart at 80km, checking whether your winter block worked. If you have ever finished a ride unsure whether you went hard or just felt like it, that is the gap it fills. Heart rate tells you how your body reacted. Power tells you what the effort actually was.
Pedals or cranks
Hub and bottom bracket power meters exist, but for most road and gravel riders the real choice is between pedals and the chainset.
Power meter pedals
The strain gauges sit in the pedal spindle. The Magene P715 (in Look KEO or Shimano SPD-SL cleat versions) and the Wahoo SPEEDPLAY POWER DUAL both work this way, and both measure each leg separately.
- They move between bikes in minutes. Summer bike, winter bike, turbo bike: one power meter and a pedal spanner.
- Few compatibility questions. Crank length, chainring size and bottom bracket standard do not matter.
- You commit to a cleat. The P715 comes in KEO or SPD-SL. The SPEEDPLAY POWER only takes Speedplay cleats. If you ride something else, you are changing systems.
- They live on the front line. Pedals clip kerbs and take hits on gravel. They are built for it, but a chainset has an easier life.
Chainset (spider) power meters
The measurement sits in the spider, between the crank and the chainrings. The Magene PES-P515 (alloy) and the TEO-P515 (carbon) work this way. Both also come as crank only, without chainrings: the PES-P515 alloy cranks and the TEO-P515 carbon cranks.
- Nothing changes about how you ride. Same pedals, same cleats, same float.
- Better protected. Tucked in by the frame instead of out at the end of the axle.
- Fitting is a workshop job. Bottom bracket standard, crank length, chainring sizes, chainline. Get one wrong and it either will not go on or it shifts badly.
- It stays on one bike. Moving it means pulling the cranks, not a five minute swap.
| Pedals | Chainset | |
|---|---|---|
| Move between bikes | Minutes | Workshop job |
| Keep your current pedals | No | Yes |
| Compatibility checks | Cleat system only | BB, crank length, chainrings |
| Exposure to knocks | Higher | Lower |
| Fitting | You can do it | Bring it to us |
| Our picks | Magene P715, SPEEDPLAY POWER DUAL | PES-P515, TEO-P515 |
One leg, both legs, or total power?
There are three ways a power meter can measure, and it is worth knowing which one you are buying.
- Left only. A gauge on the left crank measures that leg and doubles it. Cheapest, and fine for training as long as your imbalance stays the same from ride to ride. We do not sell these.
- Total power from the spider. This is the P515. Everything both legs put through the chainrings is measured, so nothing is doubled or guessed. You get an accurate total, not a true left and right split.
- Both legs, separately. The P715 and the SPEEDPLAY POWER DUAL. You get the total plus a real left/right balance and pedalling metrics.
For training to zones, total power is all you need. A true left/right split is worth paying for if you are coming back from an injury on one side and want to watch the balance, or if you simply want every metric going.
The details that catch people out
- Charging. Everything above is rechargeable. Magene quotes up to 120 hours a charge for the P715, which is weeks of riding for most people, but you still have to remember the cable.
- Zero offset. Do one from your head unit before any session where the number matters, especially when the temperature has changed. It takes ten seconds.
- Crank length. Buying a chainset meter is the moment to check whether your current length actually suits you, rather than copying what came on the bike.
- Your head unit. All of these pair over ANT+ and Bluetooth, so any recent computer works. If you need one, here are the bike computers we sell.
What about indoor training?
A smart trainer already measures power, so if you ride mostly indoors you may not need a power meter at all. Our KICKR vs KICKR CORE comparison covers that side. Where a power meter still earns its place is consistency: the same device giving you the same number inside and out.
So which should you buy?
- More than one bike, or a turbo bike, and you ride KEO or SPD-SL: the Magene P715.
- You ride Speedplay: the SPEEDPLAY POWER DUAL.
- One bike, and you want to keep your pedals: the PES-P515, or the TEO-P515 if you want carbon.
- You only want cadence: a speed and cadence sensor does that for a fraction of the price.
Everything is in one place on our power meters page. If you are not sure what fits, send us your bike, bottom bracket and the pedals you ride, and we will tell you which one works and what it costs fitted.