speed watts

[John Tolhurst]

Just did a little calc using this: http://www.recumbents.com/wisil/simul/HPV_Simul.asp

If I have a 500 watt motor, I would get to go 35 mph, 55 kph.

If I then peddle to supply another 100 watts, I get up to 37 mph, almost 60 kph.

 

[ak-tux]

Great stuff! Another nice

Great stuff! Another nice calculator here: http://www.kreuzotter.de/english/espeed.htm

 

[Eric Winn]

Interesting. I've been

Interesting. I've been experimenting with my KICKR which has a power meter buiit-in.

The other day I set it to Erg mode for 160W, pedaled an average of 80rpm for 45 minutes and averaged 30.6mph (49.2kph) for 23.5 miles (37.8km). See my ride data here.

According to Warren's calculator (nice guy, met him at the Waterford races) I achieve 23.12mph (37.21kph) but I can't input all of the actual relevant data.

According to the krezotter calculator (which I like better as it provides more input options) I achieve 20.7mph (33.31kph).

This leaves me scratching my head - going to have to read more about the Erg mode setting on the KICKR....

I want a power meter for the bike so I can compare actual road work with different KICKR settings to see how they compare.

I've been watching for the Stages Cycling power meter for my SRAM Rival crank as it has been on backorder for quite a while now. I don't know if this is from questions raised by the DC Rainmaker review or they are just not able to keep up with demand. From the looks of their Facebook page and their website they seem to be selling well.

-Eric

 

[John Tolhurst]

You can get any result you

You can get any result you like with Warren's calculator, as long as you input the right CdA. Speed per watts is far more sensitive to CdA than anything else. You can take real world observations and reverse engineer to get to CdA.

 

[Jeremy S]

wind tunnel

Just curious John, have you ever had the Vendetta in a wind tunnel? I imagine it's not easy to get access.

 

[John Tolhurst]

I havn't. But there is one in

I havn't. But there is one in North Carolina I think - pricey. For now, as long as you keep consistent the way you generate data off the garmin, its possible to discriminate between different aero measures.

 

[Charles.Plager]

I havn't. But there is one in

I havn't. But there is one in North Carolina I think - pricey. For now, as long as you keep consistent the way you generate data off the garmin, its possible to discriminate between different aero measures.

You can do roll down tests where you ride to a given speed at the top of the hill and from a given point, coast. Vary the initial speed and record the data. Assuming a constant (versus speed) force for rolling resistance and a squared piece for aerodynamics and you should be able to solve for relative differences in aerodynamics.

You want to do this with no wind (or, at least, have an accurate mesure of wind direction and speed).

Get to it and let me know how it goes.

 

[Eric Winn]

I can confirm that if you

I can confirm that if you unclip the bent knee on a coast down and straighten the bent leg leg so both legs are straight in front, you will roll further.



-Eric