30+ mph

[bootaggie]

Best way to get to 30mph+?
all suggestions welcome- BBSHD

[AZguy]

BBSHD with a 48V battery has no problem getting my tank of a fat-tire bike to 30+...

[bootaggie]

That with or without pedaling? Mine is pretty consistent at 25mph

[AZguy]

Have you fiddled with the controller parameters?

[AZguy]

I can't pedal that fast so it's definitely throttle only. I've gotten it as much as 35mph [and it was still accelerating slowly] a couple of times but that was more than fast enough for me...

It may be your gearing. My top gear is 39t chain ring and 11t rear cog...

[ncmired]

Reduce mass, air resistance, and mechanical drag (tires, hubs, brakes) where possible.

[AZguy]

With the exception of hubs mine is terrible on the rest

[bootaggie]

What kind of suggestions do you have with configuring the controller?

[Poco Askew]

What is your high gearing and tire size?

[ncmired]

What is your high gearing and tire size?

In my case, a BBSHD pulling a 42 / 18 front / rear gear ratio, 1:1 via the IGH through 700C-38 tires works out to 55 gear-inches - with this setup I think the motor RPM is maxed out on level ground, at 32-33MPH. Being just at the peak motor RPM means that the bike maintains speed pretty well on slight inclines. I don't know how well it would pull another 10 gear-inches.

And, no, I can't pedal anywhere near that fast (~140-150 cadence) so, it's all motor.

Unfortunately mass (~380lbs), air resistance (upright barn-door), and mechanical drag (IGH) are all putting a hurt on the speed.

[bootaggie]

What is your high gearing and tire size?

I am tuning the bling ring on the Roam 2. The tires are 700x38

[ncmired]

I am tuning the leakiest bling ring on the Roam 2. The tires are 700x38

So, a 42 front - what top speed do you get on the 17 tooth rear sprocket (4th smallest) on level ground?

P.S. yeah, it's gonna be a little too cold to perform speed tests right now ;-)

[bootaggie]

So, a 42 front - what top speed do you get on the 17 tooth rear sprocket (4th smallest) on level ground?

P.S. yeah, it's gonna be a little too cold to perform speed tests right now ;-)

About 25. Just starting to get little cold in Texas

[AZguy]

42 / 18 ≈ 2.33 vs. [mine at] 39 / 11 ≈ 3.55 so my max speed limited by motor RPM would be ~1.52x yours (i.e. you have ~66% my maximum). So let's say I can go 40mph you'd be limited to ~26.3mph

I'm pretty certain you'll need a higher ratio to exceed 30mph...

[cupid]

In my case, a BBSHD pulling a 42 / 18 front / rear gear ratio, 1:1 via the IGH through 700C-38 tires works out to 55 gear-inches - with this setup I think the motor RPM is maxed out on level ground, at 32-33MPH. Being just at the peak motor RPM means that the bike maintains speed pretty well on slight inclines. I don't know how well it would pull another 10 gear-inches.

And, no, I can't pedal anywhere near that fast (~140-150 cadence) so, it's all motor.

Unfortunately mass (~380lbs), air resistance (upright barn-door), and mechanical drag (IGH) are all putting a hurt on the speed.

My bike came with 700C 38mm tires; I am thinking about getting wider 700 x 45 mm tires. How would that effect the top speed? Probably it won't affect max speed but I would just get better rider comfort and tracking right?

[ncmired]

1/4 inch wider I'd think would soften the ride, depending a little on the pressure. Dunno about the top speed - hard to discern what a tire will do.

Like me I guess, my bikes are facing old age. I'm finding it hard to wring out 30mph anymore and I don't know why (probably drag).

'm focusing more these days on range and using 20mph now as my common reference / test / comparison speed.

[tklop]

...I'm focusing more these days on range and using 20mph now as my common reference / test / comparison speed.

Yeah--anything above about 16 to 18 mph, and the wind-resistance begins to build exponentially.

Unless piloting some ultra-aerodynamic bubble-bike, we're really only turning battery energy into headwind above about 20mph.

I know it's not so easy to slow down these days--it's sort-of a rush-rush-rush-rush-hurry-up world. But there's definitely advantages to slowing down--not just the obvious boost to effective battery-range.

I find I am more fully immersed in the riding experience--more able to enjoy the scenery, etc. if the wind in my ears isn't deafening--and if I'm not having to squint into a storm-force blast of wind (and dust and bugs)...  In fact, find I rarely get bugs in my mouth or eyes at all if I'm keeping at or below 15mph or so... Also, I find that I actually have more physical endurance--so that even though riding a little more slowly, I can actually cover a greater distance. Because it's less stressfully exhausting, the slower I go, the less I have to "ride my reflexes"--so that means I can relax more; and can therefore go considerably further on any given day. Reductions in speed benefit range--in terms of both battery and body...

Sure--admittedly--more often than not, I'm buzzing around closer to the 20mph end of things when I'm just commuting. But if I want to take a longer trip, it's incredible what a two or three mile-per-hour reduction in speed can do to my effective range...

I'm certain my 4KW Cyclone will propel my bakfiets well over 30MPH--and whenever I plop the DD front-wheel hub-motors on it, its potential top speed might be faster still--I've really no idea. But on that machine, fast genuinely isn't fun--it's terrifying! I've currently no machines which I'd feel safe riding on at 30 mph sustained.

But certainly, on the right machine, fast is fun--no doubt about it. And I'm not here to rain on anyone's parade (though if it does rain--it's a good idea to slow down--it's not just your own controllability, it's the visibily of other drivers you gotta take into account--but I digress)... So--yeah... For all you speed-demons--hey, go for it! I guess for me, if I really want to go faster on e-transport, I'll just take the NS train. It too is electric (powered by 100% wind-energy), and hits 140+kph between stops!  :-)

I'm enjoying reading the discussion and seeing folks' experiences and strategies...  

Best of luck with your projects, everybody!

Take care,

Tklop

[Gr8fun]

My bike came with 700 c 28 tores the largest i could get in the frame was 32. I ditched the the rim and went to 27.5 (650b?) A schwalbe energizer plus with taller sidewall and 2.00 inch tire made the handling much better . no sacrifice in speed. Full rim- tire diameter even the same. Comfort increases with lower pressure, but extreme efficincy loss. Keep pressure up.
Range has been most affected by adding a fairing ( solar) reduced wind resistance by 3 watt hours per mile at 20 mph. And top speed by ? Over 36 on bbso2.
Never charge.