Psst.. wanna buy a cheap power meter?

[Rocket Man]

For small volume production' date=' casting / forging is not cost effective.

 

CNC the spider from aluminium. Start with 6082T6.

[/quote']

 

You could be right. I'm keen not to make the complete spider - it's realy just an adaptor between the spider and the rings.

[Gumpole]

 

What about a PM that uses a HRM and converts the Heart rate effort with the other variables that the HRM records into watts.

 

Q??

 

 

Isn't that going the iBike (?) approach? Thing thingy that measures wind resistance and all' date=' and is pretty much universally denounced as useless...
[/quote']

 

Yes the i bike thingy was a good idea but (i believe and stand to be corrected) relys on the measurement of airflow, which as we can be rather iffy.

 

What I was suggesting was not to measure airflow but to rather use the effort as recorded on a hrm and convert this to watts.

Power measurement and recording is obviously more accurate by the use of strain gauges or other mechanical devices that react in relation to the "power" appllied, but they are not cheap especially when you try to fit them onto weight concious bicycles.

 

Therefore I was wondering about a conversion factor being incorporated into a HRM software using the already vast amount of power VS heart data that has been gathered over the last few years.

 

Granted it might not be 100% accurate (how do you know for sure your current power device is 100% correct all the time), but as long as it remains consistent, this would be cheaper than the available options of power measuring devices.

 

 

 

 

 

 

The Power Fundis on this forum are going to hang you from a tree for suggesting this!!

 

 

Gumpole2008-04-24 04:39:56

[bob_the_builder]

 

 

What about a PM that uses a HRM and converts the Heart rate effort with the other variables that the HRM records into watts.

 

Q??

 

 

 

Isn't that going the iBike (?) approach? Thing thingy that measures wind resistance and all' date=' and is pretty much universally denounced as useless...

[/quote']

 

Yes the i bike thingy was a good idea but (i believe and stand to be corrected) relys on the measurement of airflow, which as we can be rather iffy.

 

What I was suggesting was not to measure airflow but to rather use the effort as recorded on a hrm and convert this to watts.

Power measurement and recording is obviously more accurate by the use of strain gauges or other mechanical devices that react in relation to the "power" appllied, but they are not cheap especially when you try to fit them onto weight concious bicycles.

 

Therefore I was wondering about a conversion factor being incorporated into a HRM software using the already vast amount of power VS heart data that has been gathered over the last few years.

 

Granted it might not be 100% accurate (how do you know for sure your current power device is 100% correct all the time), but as long as it remains consistent, this would be cheaper than the available options of power measuring devices.

 

 

 

 

 

 

Ya, you mean like taking the powercalc software here:

http://www.machinehead-software.co.uk/cyclists_power_calculator.html

 

and building it into a bike puter... dunno... it looks like it has too many variables to update "on the fly"

 

[jeremyd]

name - cyclowatt

[Le Tour]

HR will always lag behind Power output so therefore I don't think the idea is possible.

 

Also Rocketman great idea if you can make it work, just be carefull about changing the Q factor.

[bob_the_builder]

 

HR will always lag behind Power output so therefore I don't think the idea is possible.

 

Also Rocketman great idea if you can make it work' date=' just be carefull about changing the Q factor.

[/quote']

 

I don't think that is much of a problem with the route he suggests, of more concern is changing the chain alignment and disrupting smooth shifting.

 

[SwissVan]

HR will always lag behind Power output so therefore I don't think the idea is possible.

 

Also Rocketman great idea if you can make it work' date=' just be carefull about changing the Q factor.

[/quote']

 

I don't think that is much of a problem with the route he suggests, of more concern is changing the chain alignment and disrupting smooth shifting.

 

No BtB think youR misunderstanding me, sorry its not easy to express da thoughts into words...

 

I'm not suggesting a HRM with some sort of power measuring mechanical equipment, rather a mathematical conversion in the hrm software that calculates power from HR and other readings such as speed, temp, inclination etc....

 

Le Tour - yes HR lags and could be a problem.... but this is a known and perhaps could be factored in (or out) mathematicaly, automaticaly compensating for the lag?

 

We can put also sorts of junk up into orbit and stop them from crashing into one another surely this should not be to difficult for the rocket scientests out there?

 

 

 

SwissVan2008-04-24 05:07:39

[bob_the_builder]

Yes, van, I think I do understand you... see a few posts above, I posted a link to the maths of which you speak...

[Rocket Man]

This thing does a direct power measurement so it's not necessary to take anything else into account.

 

To which Q factor do you refer Bob?

 

What about calling it "Power Hubber" after the input from this forum?

 

Names so far:

cyclowatt - jeremyd

Power Hubber - RM

[linnega]

Le Tour - yes HR lags and could be a problem.... but this is a known and perhaps could be factored in (or out) mathematicaly' date=' automaticaly compensating for the lag?[/quote']

That would mean that you could never use the power tool for current readings unless it can be programmed to predict whether your heart rate is going to increase or decrease in the future

[Le Tour]

Le Tour - yes HR lags and could be a problem.... but this is a known and perhaps could be factored in (or out) mathematicaly' date=' automaticaly compensating for the lag?[/quote']

That would mean that you could never use the power tool for current readings unless it can be programmed to predict whether your heart rate is going to increase or decrease in the future

 

A bit of a prob hey?  WOuld be easier the other way round Power to HR.

[Christie]

@RM the Q factor is the width between the pedals. Not something you have to worry about.

[bob_the_builder]

 

@RM the Q factor is the width between the pedals. Not something you have to worry about.

 

Yes, but changing the chain alignment or the distance between the two chainrings is a problem...

 

[SwissVan]

Le Tour - yes HR lags and could be a problem.... but this is a known and perhaps could be factored in (or out) mathematicaly' date=' automaticaly compensating for the lag?[/quote']

That would mean that you could never use the power tool for current readings unless it can be programmed to predict whether your heart rate is going to increase or decrease in the future

 

  Hey its an idea, kind of hoping someone with an open mind, foresight and great maths skills could solve the problem.

 

Once skaapies people thought the world was flat, and some still do

 

 

[Christie]

@ bob: The plan seems to be just replacing the spider, so the chain alignment & Q-factor will stay the same as the original crankset's

[bob_the_builder]

 

@ bob: The plan seems to be just replacing the spider' date=' so the chain alignment & Q-factor will stay the same as the original crankset's[/quote']

 

Dunno hey...

 

RM's first post on this thread:

"Basically you take the rings off, bolt the "power disc" onto the spider then put the rings back on but rotated slightly"

 

He doesn't want to replace the spider as I understand it. So maybe the space between the rings stays the same, but both of them move "outwards" Ok, so I depends on how much they move out, but in the overall product process surely it should be looked at from an integration into the existing groupset point of view?