If the build will be a bbso2 with 46T chainring, to a 11T on the rear wheel. Any idea of the possible top speed on a level street? Next question is there any danger of the motor overheating causing damage at higher speeds? Thank you.
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Way too many other variables to give even a good guess -
You haven't even mentioned what kind of bike, let alone tires, battery, wheel size, cassette, weight, voltage, etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc.
Give all the information you've got , whether you think it's worthwhile or not...
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With that setup you could likely do in the 30's - mid 30's give or take best guess
With a 46t ring you'd likely get top speed in a lower gear but even in top gear the ring will likely be turning very fast - likely around 100rpm... point being that these kinds of speeds are likely just throttle
I run an 11-50t cassette and a 46t ring is just a little too high for me in the lowest gear for off-road - on that cassette I'll run 42t or 44t rings
But as ncmired says battery will go very fast at those speeds anyway and it wouldn't be the best idea to pour the full 28A into a bbs02 for a long time too
Realistically low to mid 20's will be ok for not killing the motor and ok battery consumption but if you can keep it to 15-20 you will go likely twice as far as mid-20's... and many times further than 30's
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Hi, and welcome to the forum.
Probably not the number you're looking for, but on the rolling portions of Lancaster, most of the time you can probably reliably estimate an average of 20mph travel time - throttle only.
As for specifics on top speed, here are but a few of the variables, somewhat in order of importance:- How fast (cadence) and hard do you plan on pedaling?
- How big/heavy are you (wind resistance)?
- How much parasitic drag does your bike have?
- What's your battery voltage, and can it supply the full 25 amps a BBS02 motor can draw?
- Going faster means less range, so how does how fast / how far enter into your needs?
So you still want a top speed number - ballpark high twenties, throttle only.
For your overheating question, applying full power to a bogged down motor, while trying to climb a steep hill is likely the worst thing you can do to these motors. They work best spun out (likely faster than you can keep up pedaling), with lots of airflow.
As AZguy wrote, you didn't supply us with much of anything to go by, and with only 1HP everything matters.Last edited by ncmired; 01-12-2022, 08:59 AM.Comment
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Are you referring to the 20MPH trip speed average I wrote (up & down mild hills) or something Luna has published somewhere?
My "high twenties" ballpark guess is just a dragging brake caliper away from 33MPH. And are any of these speed results believable (repeatable conditions, average riding both directions over the same distance, calibrated measurement equipment)?
Like e-bike manufacturer battery range quotes, they're all very questionable.
P.S. 47MPH, with a stock BBS02 strapped to a standard triangle frame bike = doubt it.Last edited by ncmired; 01-12-2022, 12:32 PM.
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Grin Technology has an E bike speed calculator. With 200W input from me it models my bike accurately. The mid drive menus are kind of hidden since they sell hub motors, but they're in there.
The other question is how fast will you be pedaling at that speed? Sheldon Browns gear calc can answer that. For gear units enter MPH @ 90 RPM or some other cadence you like. Then pick some gears that match your top speed.
if you gear for a street legal 28MPH @90 RPM you will probably be pretty close to what that bike can do.Last edited by Retrorockit; 01-12-2022, 10:26 AM.Comment
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Why the BBS02's over an HD? A Direwolf and bike with 12 speed eagle it doesn't seem like you are pinching pennies so not a cost thing. Again the direwolf is a big chunk of weight so not pinching grams. And then questions seem to focus on top speed which makes me nervous, seems like just going with the HD to get as heavy duty that is practical with this sort of kit.
Looking at the bike it looks like typical modern geometry with a smaller triangle so a dire wolf may be a tight fit on the smaller frames. It does look like they have a dent in the chain stay for a larger chain ring so that is good but I didn't see any pics looking down to see what the rest of the space look like. Specs say 1x 34t and 3x 42t so the dent is likely for the 42t. Its good that they rate it for a 3x, that usually means the overall spacing for chain line has a pretty wide range which is good for conversions. Maybe the 02 will fit slightly better but if it doesn't you won't really have any room on it for spacers since you are starting out with a 73mm BB. The 73mm HD has a longer shaft with more threads than the O2 so you can do a couple spacers if you need em and in most cases you don't have to screw around with different offset crank arms to clear the frame on the non drive side.
I'm not saying the 02 is a bad unit but what I'm getting from this thread makes me think the HD would be a better choice unless you have some specific info on how each model fits this specific frame. The gear case is slightly smaller on the 02 so its possible that it will tuck into that frame like it was meant to be and the HD will hit the frame in the worst possible spot to require the most spacers but the reverse could be true too where the HD needs a spacer but other alignment aspects outweigh the spacer. Having the choice between models is one great thing about the BBS's.
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I’m running a giant talon 27.5 clocking in at 52lbs with Luna bbshd and 52v20ah jumbo shark. 42T lekkie. I weigh 215lbs and I don’t get over 27mph on throttle. 30mph with PAS. I probably have to play around with a new cassette. Right now it’s shimano 11-34.Comment
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I'm just wondering if he is in too high a gear and running out of torque. Maybe down a gear or two would get the torque back up but I suppose could spin out. One way to get a clue is try and pedal. For most people if you can easily keep up with the motor you are in too high a gear for the motor to be in its optimum range. The motors sweet spot seem to be at or just above the speed most people can spin at. Its not a big deal if you are just out for a cruise and want to pedal that the motor is running on the slow side but if you are trying to extract maximum performance it makes a difference. -
He's saying 42t and my tires are pretty close to the same diameter - I can go easily over 30mph even with my higher rolling resistance with 42t into 11t - even can do that with 44t into 11t... dropping to 13t or 15t will pick up some speed but it's not much
I'd be looking at the controller setup
Also, if there's any slope or wind that will really eat away at top speed and if the battery is low that can hurt too
Another thing to consider is how he's measuring speed - the speedometers on the displays are usually pretty rough
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My bike is a 29'er with 29x2.6 tires with a 30" diameter and the bafang speedometer is accurate with them. Total weight is 325#. 48v BBS02B. 44t chainring and 11t rear cog. On a full charge I max out at 32mph on flat ground, pedaling until I'm out of gear, 30mph without pedaling. A 46t chainring would only be enough for around 35mph. A 46-10 gear may get you around 38mph. Keep in mind this only applies to larger 29" tires. I doubt 45mph would be possible with a 52-10 gear on small 26" tires. The motor has a max rpm that it can spin and there is a max rpm that you can spin the pedals. Tire circumference plays a part because it's what determines how far you travel for each wheel revolution.
The fastest I've had it was 46mph on a long and fairly steep down hill. If I were a little more aerodynamic I'm sure 55 would be doable.
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