[Question] What is the cheapest power meter. (Can be purchased from either UK or USA)

ajmarshal1 wrote:

Loads of people have kitchen scales. Not many people have powers meters. Low volume = high cost.

I know, that's why I mentioned manufacturing scale, but there are also manufacturers who can do shorter runs that still don't cost proportionally more. The cost of applying a strain gauge network for a power meter appears to be many more times that from a commercial unit - at least from comments from power meter company staff i've heard over the years, although clearly they would wish to emphasise the high quality, hand-nibbled lovelyness of it all.

(edit) Just to clarify - it's always going to be more expensive than a kitchen scale, but I didn't say it should be the same price just that it should cost proportionally less than it does at the moment and that some of the cost could probably be removed if the enhancements for extra accuracy - which are not necessarily needed by most - were not included. Just Good Enough should be cheaper even modulo pricing structures.

bashthebox wrote:

Power meters are a massive racket, aren't they? It's a strain gauge and an ANT+ transmitter.... and apparently that's worth 700 quid or so. I reckon at some point someone like Decathlon'll come along and do one for under a hundred quid.
I really, really want one though.

They can be over-priced - especially if you just want "good enough" power readings - but they'll still hard to get accurate, consistent and cheap. If you've not already seen it, I recommend looking back at the work Keith Wakeham did with DIY power meters (and the jolly good ANTRide sensor) before he went to 4iiii.

It does seem odd that strain gauge-based kitchen scales can be produced for buttons but we still don't have a bargain basement power meter to match. Accuracy is nice to have, but not essential to the n'th decimal point, but consistency is a must have. Part of the lack of cheap power meters inevitably is pricing (IIRC there's a good discussion about that in the first 4iiii Precision article from Ray Maker), part of it manufacturing scale, R&D and so on - and part of it the extra precision and consistency they're trying to get.

An example of that last one is the use of accelerometers to help with calculating/estimating the crank angle and true angular velocity at various parts in the pedal cycle rather than estimates over a full or (guessed) half cycle using a cadence sensor or similar. The underlying technology is still cheap but it needs to be researched, tested, calibrated, integrated, made robust etc etc....

At the moment 4iiii seem to have the current best bang for your buck in that a single-sided power meter is now under 300 quid - and it's upgradeable to dual-sided. Watteam may get their dual-sided one out for under £ 400, which seems good value if it works - so it's still on the way down with room to go lower, but understandably no-one wants to sprint straight to the bottom just yet, they'll get there in end though. It's already a completely different world to only a couple of years ago.

There will always be a market for things like SRM and InfoCrank - but like you, I look forward to the day when we can get hold of a "kitchen scale" accuracy power meter that's consistent enough to be useful. No, we're not there yet - but we're not a million miles away either... anyway, that's my take on it which may have bugger all to to with reality

pablo wrote:

Bugger not 4iii Brimbrothers is speedplay only. 4iiii won't work for me either unless I change crank set I have FSA carbon arms.

Are the inside of your crank arms flat? If they are it should work. Contact 4iiii and ask.

pablo wrote:

The 4iii system is speed play only which could be a problem. Speed play pedals seem pretty expensive (on wiggle at least £80) i've got two bikes and am looking to get a third so would be expensive to change system. If DC Rainmaker gives any cheap power meter a good review i will probably sign up.

The 4iiii Precision is a crank arm power meter with a DIY fixing kit - much of the dev of it was down to Keith Wakeham (he of the DIY power meter) who 4iiii hired. Ray Maker also has (had ?) a 10% discount code for them which was working towards the end of last year - no idea about now. His review of a pre-release version is here

http://www.dcrainmaker.com/2014/09/4iiiis-introduces-precision.html

pablo wrote:

The 4iii system is speed play only which could be a problem. Speed play pedals seem pretty expensive (on wiggle at least £80) i've got two bikes and am looking to get a third so would be expensive to change system. If DC Rainmaker gives any cheap power meter a good review i will probably sign up.

Speedplay only?

I have absolutely no idea where you got that from. Pedal system has no bearing whatsoever on what is a crank based system similar to stages.

glynr36 wrote:

Depends what you want;
Crank - single side or dual
Pedal - single side or dual
Hub.

I'd be weary of all these start ups giving 'cheap' power meters, or one you have to mount yourself, just not a controlled environment and introduce more variables.
Stump up for what they're worth, or if that's too much look second hand or wait for prices to drop. I can see the vector S dropping below £500 Q3/4 of this year.

4iii IS proven and you can pay for install. I've seen the protos tested and they're as consistent as anything else out there. I say that as an SRM owner.

I know what I'll be spending on my next PM and it won't be more than £400.