Equivalent MPG of cycling - garage feature?

[MetroMPG]

The plan from the start has been to add a Garage feature for cyclists. There are 2 approaches we could take (or both, I guess)

• A simple comparison, showing the proportion of biking vs. driving

• Peakster suggested factoring bike (or any hpv) distance travelled in a way that gives "combined" MPG with your car(s). EG. if you got 40 MPG last month in your car, and covered 100 miles, but you also rode 100 miles commuting by bike, your total transportation FE for the month is 80 MPG.

• Another approach is if your bike computer calculates/estimates energy output, you could just do the math and figure out equivalent FE like I did with the ForkenSwift "MPGe".

How do you figure MPGe for a bike, someone helpfully asks?

I was trying to figure how to come up with a MPG equivalent for the bike, like you did for the ForkenSwift. I have a power meter that gives me the following data:

kJ
ave watts
time
distance
miles
Ave speed

The MPGe formula would simply be distance (mi) / gallons equivalent.

Here's a conversion site that will give you the US gallon equivalent of gasoline in kJ (and lots of other conversions): http://www.onlineconversion.com/energy.htm

1 kilojoule = 0.000,007,589,6 gallon [U.S.] of automotive gasoline

So if you rode 100 miles and the computer said you used 11,300 kJ then your MPGe is...

100 miles/ (11,300 kJ * 0.000,007,589,6 kJ/gal)

or 100 miles / 0.08576248 GALe

= 1166 MPGe

[MetroMPG]

PS - anybody want to check my math?

Also, I just kind of picked the kJ figure for going 100 mi. out of a hat, based on one reference I saw after a quick google. It could be wrong.

[SVOboy]

How many people actually have meters that calculate wattage though? Powertap!

[MetroMPG]

And how accurate can they be? What do they measure - heart rate? Body temp?

[Lazarus]

Very nice. I don't know how many will have the computers that will figure kJ so it would probably just be best to use some form of the combine FE. I'm trying to picture how that would work. I guess you would have another column in the garage that has transportation index? Would it be on the rolling 90 day average also?

[MetroMPG]

I like the combined FE idea too.

I figured it would just be for the year. That would be easiest, to start.

It makes for another cool top 10 list, plus it would show in your individual garage.

[Lazarus]

Originally Posted by MetroMPG

And how accurate can they be? What do they measure - heart rate? Body temp?

Some are pretty accurate. Here's the poop.

[SVOboy]

Powertap actually calculates energy output, that's why they cost 1000 USD and not many people have them,

[igo]

Originally Posted by SVOboy

How many people actually have meters that calculate wattage though? Powertap!

Thats what I was thinking too. I would like to have a month by month bike mileage chart like this:

http://www.bike-pgh.org/resources/submit-your-miles

Route slip has a nice graph based on week to week mileage (it also shows the amount of climbing too, based off of google maps):




If you want to put a more environmental spin on the graph. You could say total mileage by bicycle X,XXXmiles = XX.X gallons saved = X,XXX lbs of CO2 saved.

[MetroMPG]

It's easy to forget how intense cyclists can be until you read something like that. Then again, I'm sure they'd say the same thing about FE nuts after seeing someone who posted a inverview with the inventor of the ScanGauge.