Seattle Forrest

Most people don't ride beyond 170 rpm. I'd bet most cyclists ride below 70 from looking at the people I see on the Burke Gilman Trail around town. When I do high cadence drills, that means beyond 110 rpm. My max cadence on a recent hill repeats ride was 138 rpm. There has to be some top end limit, and most power meters have it set high enough not to be a practical concern for most customers.

I was surprised to learn that I was producing no power when I'd track stand. Do it up a hill and it sure feels like you're powering the bike. But if you stop to think about it, your cadence is zero and any torque times zero speed comes out to no power. Also if you think about it, I'm not moving the bike, and that doesn't require any power, I could lean it against a wall to keep it from falling down the hill and the wall wouldn't be applying power to the bike any more than my trackstand.

A.Z.K.

Well as we all know a power meter can be a great training tool. If its limited to 2000w and you push over 2000w even for 1 second your 5sec or even 10sec average will be inaccurate & inaccurate data makes training with power less useful.

It's not uncommon to work for an entire year for a 5% gain, so accuracy is important.

Seattle Forrest

Accuracy is for sure important, but in this world everything is a trade-off and you have to weigh things to see what's worth it and what isn't. Training isn't a very demanding use of a power meter, you don't need great accuracy, that's why people are able to use single pedal/arm meters (like Vector S and Stages). People also use power meters to test aerodynamics; if I put out 250w on the flat on a windless day in this posture, then go back and do it again in a slightly different position, which nets me more speed?

Ok so your 10 second average is skewed. Let's say you hit 2,200w for a full second, then dropped off to 1,800w; 1,400w; 1,200w; 900w; 850w; 800w; 750w; 745w; 700w. I haven't seen your data so I'm guessing numbers based on what might be reasonable. That comes to 1,134.5 vs 1,114.5 watts for your 10-second average. Because you held your peak power output for a very small portion of those 10 seconds, it didn't influence the whole very much.

Also for training purposes what usually matters is your 60 minute average, or your 20 minute average if you use that to estimate your FTP.

This is why people have been using power meters so successfully for years. Stuff like this seems like a really big deal in theory, but in practice anomalies like >2 KW peaks are a drop in the bucket.

McBTC

True, there's no benefit to having an instrument that is capable of measuring a component of power generation -- e.g., 'pedal rate' -- that's well-beyond the optimum for maximum power generation.

According to research by J.C. Martin, et al. (Determinants of maximal cycling power: crank length, pedaling rate and pedal speed), unlike 'pedal speed,' the optimum pedal rate does not vary much over a wide range of possible crank lengths --i.e., "The optimal pedaling rate for the 195-mm cranks did not differ from that of the 170- or 220-mm cranks..."

Nevertheless, there was a relationship: "The optimal pedaling rate decreased significantly with increasing crank length, from 136 rpm for the 120-mm cranks to 110 rpm for the 220-mm cranks."

Accordingly, for a range of crank lengths available to riders, maximum power is produced in the 110 to 136 rpm range, not above 170.

A.Z.K.

Yes you are right, I created this thread more out of curiosity to why mechanically a power meter is limited to 2kw.

Here is a Graph of how the ride power data looks with a few sprints. this was a short 3-5sec burst the graph kicks out again at around 5sec where a other effort overlays it. It drops off again around 12-13sec (200m done).

Seattle Forrest

You have a lot more power to throw down in a sprint than I do. I've been proud of myself for being able to do a horsepower for five seconds...

A.Z.K.

Ah well its all about w/kg and i'm rather heavy

Seattle Forrest

It's only w/kg going up hill; if your aero profile isn't that different from mine you'll lose me on flat ground.

I don't know how the mechanical stuff comes together all that well, I understand it at a really high level but not in detail. I hope some of what I've said about how people are using them has been even a little bit helpful. Sounds like there are a few meters that will do what you're after, but if you already own a dual sided Vector it'll cost a lot to switch. You were talking about working to improve, holy crap I'd be thrilled to have your numbers though.

A.Z.K.

Yes the information you have shared has been helpful.

The data above was recorded on a Stages power meter, which eventually broke. I then got the vectors which I have now also returned due to extremely inconsistent data after a few month of use (they claim a 90kg weight limit). I'm in the market for another Power meter probably towards the end of the year. I was thinking about power2max or quarq, customers seem quite happy. SRM Road is a bit out of the price range and still limited to 2000w. it seems verve infocrank (only 110bcd) and SRM Science are the only +2kw options and are both even more expensive. 4iii needs a flat crank which i guess i can get but i don't know to much about that product.

I used to do powerlifting which really helps in explosive situation, especially mentally. I'm happy with my sprint numbers, but there is always that little bit inside everyone that wants to go even faster

Seattle Forrest

I know Vectors have a weight limit, I'm over it slightly and wasn't aware until after I bought them. Got hit by a car a week ago and I think mine are shot (along with my bike) so I've been doing a lot of research into the situation. Powertap P1 pedals don't have a listed weight limit, I called them on the phone and they said they've been tested internally up to 300 lbs (135 kg). I can't find a max power spec for them, though, so I have no idea if they're a better option or not for you?

https://www.powertap.com/product/powertap-p1-pedals

I've never used a power meter except Vector pedals so I'm going to shut up before I steer you wrong.