5

I can't easily change my crankset or hub, so I'm looking at pedal power meters. All of them (PowerTap, Garmin Vector, bePRO, Xpedo Thrust-E) use Look/Keo/SPD-SL cleats. For me, walkable riding shoes are a must.

Are there adapters from Look/SPD-SL to SPD cleats? Is there another solution to this problem?

ETA: I said I can't easily change by crankset or hub. Please don't reply telling me to do that. The reason being, I have a Pinion gearbox which doesn't take custom cranks, and I have a 158mm rear axle which hub-based power meters don't fit.

Improve this question
2
  • 4
    Roll your own: instructables.com/id/Bike-Power-Pedal-IoT
    – R. Chung
    Commented Oct 30, 2017 at 17:49
  • 2
    The reason solutions are hard to find is that almost all power meters are made for road bikes. There’s little market at the price point that a MTB hardened power meter would sell for. Road biking is about continuous power over long periods of time, where a power meter is useful. MTBing is about instantaneous power in which a power meter is less useful.
    – RoboKaren
    Commented Dec 15, 2017 at 0:29

5 Answers 5

Reset to default
7

I know I am late to the party, and maybe this is too late for the OP. However, the facts have changed since the last two answers: SRM just announced a set of mountain bike pedals that are compatible with Shimano SPD cleats. The price is 1,000 Euros. The link above goes to an industry observer, and he thinks US pricing could be similar. Availability in December, 2019.

The pedals are expensive compared to existing road bike power pedals that we know are good (i.e. Favero Assioma and Powertap P2). I suspect that making MTB power pedals is difficult, because MTB pedals can take hits from ground strikes, and they're more exposed to dirt. Any MTB power pedal would need its electronics protected against all that. Also note that SRM has always been a premium power meter option, i.e. their prices are very high, and their Look-based road pedals are very costly (US$1,700 for dual sided, $900 for single-sided).

It does seem likely that other companies will target MTB power pedals in time. In fact, IQ2 (I believe it's pronounced "IQ squared") announced an MTB power pedal (also SPD compatible) earlier than SRM released theirs. The issue is that IQ2 had initially got crowdfunding for a completely different design - they were designing pods that you inserted into your cranks, and then you inserted pedals (any type) into the pods. They found this to be infeasible, and they switched production plans to road (Look compatible) or MTB pedals. They plan to charge 329 EUR for the MTB pedals, 299 for the road pedals.

However, if you read between the lines at the link, the writer seems to think it's quite possible they won't deliver at all. If you read the comments, a lot of people come right out and say that they're expecting failure. The writer (DC Rainmaker) is a long-time industry observer and commenter, and I would place a lot of weight on his opinion. Also note that his post stated that the patent on Shimano's SPD pedals appears to have expired, and this could allow existing companies to create SPD pedals without licensing fees. That could lead to more MTB power pedals soon.

To expand on @Criggie's answer, the PowerPod estimates power from wind resistance and accelerometers. I believe this is more technically complicated than measuring strain at the crank/chainring/pedal spindle and translating that to power. DC Rainmaker has some reviews of their technology, but my sense is that this type of power meter is much less developed than direct force power meters.

This was alluded to in comments in Criggie's answer, but I believe the PowerPod has to assume the coefficient of rolling resistance. That is obviously going to vary between road and off-road, but off-road is a pretty diverse set of terrain. Furthermore, detecting the transition between road and off-road may be challenging, not to mention detecting transitions between types of off-road terrain (e.g. fire road, fine gravel, rough gravel).

Improve this answer
2
  • Thanks for the heads-up! I will keep an eye out for either the SRM or IQ2 pedals' release.
    – danarmak
    Commented Sep 7, 2019 at 17:37
  • 1
    Things have changed again. DC Rainmaker just released a preliminary test of the new IQ2 road pedal and his tone is much more optimistic in this review. dcrainmaker.com/2020/05/… Based on the iqsquare website it appears they are trying to target a July 2020 delivery for their SPD power meters but they have had delays before.
    – John Neville
    Commented May 18, 2020 at 22:41
5

Not answering your question directly, but this is too long for a comment.

There are other places to put a power meter than your pedals/cranks.

  1. In the wheel hub , example is https://www.powertap.com/product/powertap-g3-rear-disc-hub. Downside is they're not cheap at $600-$800 USD, plus you need to build them into a wheel so not easy to move between bikes

https://www.powertap.com/Uploads/Powertap/2015/3/hubs_g3_disc_142mm_thru.jpg from above web site

  1. Not a solution for you, but its possible to put the power meter in the cleat. http://www.magnes.ch/sports/ Sadly its a road style and isn't overly walkable.

http://www.magnes.ch/wp-content/themes/magnes/assets/image/features.png from website above

  1. Leave the power meter completely away from the transmission... http://www.powerpodsports.com/ is a wind-based power meter. I have no idea how it works, but at $300 its also half the price of other power meters.

http://www.powerpodsports.com/wp-content/uploads/2016/05/PowerPodBlackCombo020216.jpg from their website

  1. Last resort is to use Strava's power guesstimate. Its pretty useless for peak power or instant power, but over the course of a ride, the average power seems "reasonable" as an estimate. Main bonus is this is free.

In addition there exist chain-based power meters, which "listen" to the chain electrically like a guitar pickup. They seem uncommon now.

Improve this answer
7
  • I can't use a crank-based solution because I have a Pinion gearbox and it doesn't take custom cranks. And I have a wide 157mm rear fork which the Powertap hub doesn't fit. Chain-based meters AFAIK are not being produced any longer. That leaves the Powerpod. That's probably my best remaining option, but it's less reliable offroad.
    – danarmak
    Commented Oct 30, 2017 at 8:53
  • 1
    You might find a crank based power meter for the left crank which can normally be removed on any system and has a standard interface. Google: 'crank based power meter' or check the stageONE website.or this review: dcrainmaker.com/2012/09/…
    – Carel
    Commented Oct 30, 2017 at 12:59
  • 1
    Some companies offer a service where you send your own crankarms and they install powermeter onto it. @danarmak wouldn't this work for you?
    – Klaster_1 Нет войне
    Commented Oct 30, 2017 at 14:09
  • I think that only works if the crank arm is of a certain construction (e.g. hollow aluminium). I don't know if the Pinion crank arms are compatible with any given company, and don't particularly want to ship abroad to find out.
    – danarmak
    Commented Oct 30, 2017 at 21:06
  • I'd guess the wind ones are as good as just getting the speed of the bike from a speed sensor and just doing some math.
    – Batman
    Commented Oct 31, 2017 at 0:12
4

I conclude there's no adapter from road to SPD pedals. I will have to solve my problem another way.

Improve this answer
2
  • 2
    You've been given a bunch of ways to solve your problem. I feel there's something you're not telling us, like that you already own something not-stated and its skewing the requirements.
    – Criggie ♦
    Commented Oct 31, 2017 at 19:38
  • 1
    To be honest, I have seen answers with solutions that either do not measure power or don't fit the OP's rather weird bike.
    – ojs
    Commented Nov 3, 2017 at 7:31
1

See this question for how to make a SPD-SL/Look pedal a flat platform. There are adapters for SPD-SL or Look shoes to SPD for using the other cleat, but you need the portruding cleat to engage/disengage a look/spd-sl style pedal. So, you can't clip in with something walkable on a SPD-SL/Look pedal.

SPD pedals are a bit tricky to fit a power meter inside just cause they're typically quite small pedals to begin with. Also, I think there may be some patent issues (which I think held back SPD-SL from getting power meters); maybe someone can verify this.

Getting a crank power meter is probably the easiest and best option.

Improve this answer
2
  • I know I can convert Look pedals to flat platforms. But can I convert those platforms to SPD? And would using two converters be rigid enough?
    – danarmak
    Commented Oct 30, 2017 at 8:52
  • No. You'd have to basically attach a SPD pedal to the flat platform, and you probably can't do that in a safe manner. Also, theres a chance it'll add enough noise / play to screw up your power measurements. R. Chung's comment is probably the best you're going to get -- your likely best bet is to hack together your own.
    – Batman
    Commented Oct 31, 2017 at 0:14
-2

I have a speed sensor that straps to the hub and also calculates power. Is this not an option?

Improve this answer
3
  • 2
    Straps to the hub? That's new to me... can you please quote a brand name to google ?
    – Criggie ♦
    Commented Nov 3, 2017 at 1:34
  • 2
    You can't calculate power using only speed.
    – ojs
    Commented Nov 3, 2017 at 7:30
  • This answer needs to be longer, and have a lot more detail to be useful. Please expand to at least 4 lines of text in your answer.
    – Criggie ♦
    Commented Nov 3, 2017 at 7:35

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.