I am looking to buy a cheapish power meter.I Would like to see if am improving at all.

I want to know my bottom bracket standard and if I can fit a bottom bracket power meter?

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    That looks to me to be a bolt. Several different standards could hide behind it -- you can't tell for sure until you remove the bolt and "pull" (with a "crank puller") the crank arm off. – Daniel R Hicks Apr 24 '19 at 12:04
  • Looks like a high-tensile 14mm hex bolt head. You'll need a 14mm socket to remove it. Both sides of the bike will be conventional right-hand threadded. Take the bolt out and add another photo, which will show if its octalink or square taper or perhaps something else. – Criggie Apr 24 '19 at 22:43
  • Also remember power meters can be on the pedals, the crank, the chain, the rear hub, or even hanging on the bars like an aeropod. You're not limited to a BB power meter. – Criggie Apr 24 '19 at 22:45
  • are there power meter for flat pedals? – Ageis Apr 25 '19 at 11:20
  • I doubt that there are flat pedal power metres. Trial, freestyle, downhill, or enduro riders are usually not that interested in the power through their drive train. Disciplines where power matters in competition use retention to pedals. Compared to the cost of power metres shoes are a bargain anyway. – gschenk Apr 25 '19 at 13:26

The bolt in the cranks means you have a 3-piece crank (separate left and right crank arms and cartridge bottom bracket, with a square taper or splined axle-crank interface).

No power meters come in this type of crank because it's old technology that only appears on inexpensive bikes these days.

However 3-piece cranks use a threaded bottom bracket shell, you can replace the bottom bracket with an external bearing one and fit modern 2-piece power meter cranks (axle is permanently joined to drive side crank). There are a few standards: Shimano HollowTech II, SRAM GXP, FSA MegaExo. To reduce cost you could find a lightly used crank on Ebay and a compatible left hand side crank arm power meter.

Another path to go is power meter pedals, which will not require replacing the crank and BB at all of course.

BTW, you don't need a power meter to track improvement. A smartphone or bike computer and Strava is a great tool for that. Power meters are expensive, given that you likely have a bike on the older or less expensive side you might be better off using the money on some bike upgrades.

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This looks like a square taper bottom bracket. Have a look at Sheldon Brown's page.

Best in mind that there are at least two popular square taper standards ISO and JIS. These are very similar and easy to confuse.

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  • I doubt there will be square taper power metres around. More interesting to your question will be what use the standard of your both bracket shell. The most convenient would be a BSA. To make an educated guess we need to know more about your bike. Year and place of origin, brand, components. Best ask a new question 'How do I get a power metre into this bike' and include a photo of the drive side of the BB area included cranks and the edge of theBB shell. – gschenk Apr 24 '19 at 11:41

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