WASYLBRYTAN said:
I cannot express how disappointed and frustrated I am with this forum. I discover something interesting and tell people about it so that they can try it and give me their feedback. But all people want to do is discredit me as if I am trying to cheat them or get money out of them.
Seriously, dude -try what and why?
There are two entirely different concepts here:
- The Nullwinds 'headwind-negating' fairings
- WASYLBRYTAN's 'range-improving' fenders
- Nullwinds is very clear:
In still air, the Nullwinds fairing has been tested to give no significant improvement.
Of particular note (see Nullwinds Drag Mechanics Document):
-
nullwinds said:
Under null headwind conditions, the predicted gains are minimal, which is consistent with road test results.
Importantly, both their new drag formulae and their road tests are consistent on this point.
- The Nullwinds maximum estimated potential speed improvement of 16% using their unreleased computational model are for a 10mph bike in a continuous 40mph headwind and only where the spoke drag is a large percentage of the overall vehicle drag.
These Nullwinds estimates are unsubstantiated by testing - the largest recorded savings by actual test were "in excess of 10%".
In any case, large heavy riders with upright posture on heavy ebikes using fat 26" ebike tires certainly fall in the category of bikes with low spoke-drag-to-vehicle-drag ratios. Nullwinds observes that such vehicles will show substantially reduced improvement.
Nullwind's claims of improvement may mislead those who believe that the power required to propel a bike at 10 mph in a 10mph headwind is the same as that required to propel the bike at 20mph in still air. However, this is certainly not the case and simply traveling at higher speed without headwind will not make the fairings work - and Nullwinds states this clearly.
- You claim a repeatable 20% range improvement with your DIY fairings in essentially uninstrumented tests:
WASYLBRYTAN said:
I continue to see at least a 20% improvement in battery range everytime I test this.
...
I ride the same route 2 or 3 times each day at the same times, speeds, terrain, weather conditions.
...
Three days ago I obtained 217 kilometres range from an 8.8 amp hour battery.
...
36 volts, 8.8 amp hours. 217 kilometres at 18 kph.
So - on a heavy draggy ebike in presumably still air (or certainly not continuos high speed headwinds day after day of your tripping) you are claiming 200% of the best test gains claimed by Nullwinds. Confusingly, your vehicle and riding conditions are flatly stated by Nullwinds to reduce or eliminate any gains by their technology.
- Looking at the figures you have supplied we see that you go 217km on 36v with an 8.8 Ah pack yielding an energy consuption of:
217km / (36v x 8.8Ah) = 1.46 Wh/km travelling at 18kph (2.35wh/mi at 11mph).
With a little math we know that a 60lb hybrid bike with 170 rider requires 7.6Wh/mi to achieve 11mph in still air.
So - you are puttering along at 11mph and are providing 69% of the power by pedaling. Your 'tests' are based on results that rely on unmeasurable and subjective rider pedal power input that is 222% of the applied motor power - hardly a compelling test scenario to claim a 20% increase in ebike range.
Returning to the question of 'what to test and why?':
- By their own statements, Nullwinds appears to offer insignificant improvements for the ebike world - wrong style bike, wrong speed, and wrong headwind requirements.
- You offer claims that contradict the testing and physics presented by Nullwinds and substantiate them only with vague and subjective tests that rely on 69% of the vehicle power from the rider at speeds that are generally considered undesirably/unrealisticy slow.
Nothing to test in either case.
