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BBSHD - What does "hot rod" programming mean?

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  • frankhouser50
    commented on 's reply
    I have a "hot rod" bbshd w/ steel 46T and 52v 21.5ah battery on a Giant Momentum fat tire at 20psi, It's my daily commuter and I average 33+ easily throttle only for the over 5000 miles.
    I'm hard on it and it delivers.
    I want to try increasing the amps from 30 to 35/40 and see how it does.
    P/S speed is from GPS.
    Last edited by frankhouser50; 04-18-2021, 08:57 AM.

  • JPLabs
    replied
    Originally posted by Tomas Pesl View Post
    Which part of BBSHD programming do I change to correct this annoyance.
    When I go from standing still the power starts slow until it reaches certain speed and then it seems to kick in to “second gear”
    It is annoying especially on steep hills.
    Thanks for any help.
    Thomas,

    My bike does the same on PAS, and I've tried a whole bunch of program changes, but never completely eliminated it. The best I've done is to set my currents high vs speed limit, and set 'keep current' low. I think my 'keep current' is at 15% now. I rarely notice the '2-speed behavior' now, but sometimes I do, and I now think there are actually two different realms, where this happens. Low cadence, and higher cadence, with different causes.

    Here's what I'm thinking...see if it could fit what you are experiencing. Especially the first, 'Low Cadence', description.

    -----

    Low Cadence 1-2 shifts (this mode happens when coming up to speed from a stop, or riding at-speed in too high a gear):
    • If I really lug it, with very low cadence, I get the 1-2 shift pretty consistently.
      • It seems like the PAS system will limit current, below the user-programmed level, at very low cadence, probably for motor protection.
      • Then, once cadence picks up, the limiting turns off, and you get full programmed current.
    So, the bike increases current in a sharp step, instead of gradually, as cadence increases. Feels like a shift.

    I am not completely sure about it, but my own BBSHD seems to do it, so I think this explanation fits the 'lower cadences' 1-2 shift symptom. I can observe this with any programming I've recently tried; it seems very consistent, with high- or low-power programs.

    I don't think this cause is programming-dependent.

    --

    Higher Cadence 1-2 shifts (this mode can happen at whatever cadence limit is set for a given PAS level):
    From my experience, I think the '1-2' shift also seems to happen when the PAS current is lower than the 'keep current' for given operating conditions, when the control transitions to 'keep current' control. I observed this more through program changes and effects, rather than by just riding the bike on a given program setting, as for the low cadence condition. Here's what I think could be happening:
    • There are two different current-control modes in the controller: PAS, and Keep Current.
      • I'm NOT sure if 'keep current' applies all the time, or only above Speed Limit, or if current is a calculation involving both, all the time.
      • If 'keep current' applies all the time, or is 'blended' continuously, then the below doesn't fit.
        • The bike runs on lower power per PAS programming, until the speed limit is reached for that PAS level. PAS power isn't called for above set speed, so it defaults to 'keep current' after speed is reached.
          • If the PAS current setting is relatively high (for example, 20A current setting) and the motor load is low, then only a low percentage of max current is needed. Say, 5A out of 20A limit for that PAS level. 20%.
          • This is "1st gear".
        • Once speed limit is reached, it switches to "keep current'.
          • If Keep current is at, for example, 50%, then the controller delivers 20A * 50% = 10A.
          • That's twice the current of the PAS setting. "2nd gear".
    Since it depends upon the PAS current, speed, and 'keep current' settings, this 2nd cause would be program-dependent.

    I'm not sure about all this yet, and I recall that AZguy had some different thoughts about it the last time we discussed this, but I've thought about it more and changed my own interpretation of the 1-2 shift, per above.

    What do you guys think?

    Thomas, if you don't think this fits, what is different in what you experience?
    Last edited by JPLabs; 10-05-2018, 12:47 PM.

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  • xcnick
    commented on 's reply
    Are you pedaling or just throttle alone?

  • Tomas Pesl
    replied
    Which part of BBSHD programming do I change to correct this annoyance.
    When I go from standing still the power starts slow until it reaches certain speed and then it seems to kick in to “second gear”
    It is annoying especially on steep hills.
    Thanks for any help.

    Leave a comment:


  • craigsj
    commented on 's reply
    38 mph on 700c road tires with a 46x17 would require a cadence of 180 rpm. Likewise, 42x17 at 33-35 mph is about a 160 cadence. BBSHD can't do that on 52V. To achieve these speeds you need at least 110 gear inches. You're claiming 70.

  • Mgbguy1
    commented on 's reply
    Thank you, I enjoy this forum a lot of great conversation but, sometimes.......

  • CraigAustin
    commented on 's reply
    That sounds reasonable. I can get to 37mph on a hybrid, similar set-up and weight, PAS 5, full throttle, sober and pedaling as described.

  • gman1971
    commented on 's reply
    On the pedaling my ass off matter, you don't know what I am capable of so please, have some respect and don't act like a 15 year old.
    Last edited by gman1971; 06-01-2016, 10:27 AM.

  • gman1971
    commented on 's reply
    I spend time thinking my replies, but you just jumped to conclusions before reading my entire post, which btw, it agreed with your findings.

    Road bike = very efficient bike, the wattage to get my carbon road bike to 30 is probably 50% less compared to what it takes for my MTB to get to 30 mph, so you're basically arguing with yourself here. I clearly stated that less aero drag = easier to get to 30, also stated from the beginning that what you described was possible but not for sustained periods of times, then you now tell me about bursts? that's what I already stated. Apparently you're now bent on proving me wrong or something.

    All motors have a finite powerband... so say your electric motor can deliver say 1500 watts at 90 RPM; and lets assume max motor RPM is 110. So, in order for you to go faster than whatever 1500W of power from motor are doing, you need to pedal above 90 RPM to match the motor RPM, so the moment you spin faster than 90, the motor reduces power b/c at higher RPM the torque drops, and b/c the RPM usually don't grow according to the torque you're dropping then you're losing power from the motor, until it hits redline, at which it will deliver zero power b/c all its power is used just to spin the motor since as there are no external loads applied to the motor shaft (your legs are doing all the work.) So lets say now you're pedaling at 95 cadence now and doing say 200 watts, the motor still is within its max RPM but now its only doing 1350 watts b/c its no longer at the RPM where it was making 1500 watts of power. So you're now doing a combined output of human/motor of 1550 watts, if you keep pushing yourself, the motor reduces power even further, so now you might be doing 1000 watts, at say 105 RPM, the motor power is further reduced down to 700 watts, so combined output of motor/human is now 1700 watts, so you will be going faster, but not 1000 watts of your legs + 1700 of the motor. Say now you start spinning evem faster, faster than what the motor redline and you're delivering 1700 watts, then you're now doing all the work yourself, b/c the motor isn't helping you a bit as you're above its max RPM and the net torque at max RPM is zero (otherwise it will keep spinning higher and higher forever, its called perpetual motion machine, they don't make those yet.) Electric motors are not internal combustion engines that have a flat torque curve across most of the RPM powerband, torque that inevitably falls to zero when you reach max RPM... electric motors deliver all torque at zero RPM, and that torque drops quickly once they get spinning, and how the torque curve drops over RPM depends on a lot of things.

    I build nice stuff that works freaking great b/c I am far from stupid, contrary to what you might think. And what was the purpose of bringing the Jacobi algebra lesson here? Any particular reason for that?

    Also, I detest math, its just another tool I use to get me to the end results, which is all it matters to me.

    Aerodynamics are far more important than anything else, doesn't matter how strong or fit you are, b/c aerodynamics can mean the difference between 500 watts getting you to 15 mph, vs getting you to 50 mph.

    G.

  • JayC
    replied
    My stock as delivered by Luna BSSHD hit ~33MPH (display read 29.8MPH set to 26" wheels) on flat ground using level 5 PAS. 52V battery driving Eclipse 42T to 11T rear - drunk 175 pound rider (not me) pedaling his ass off on 50 pound bike w/ 29" wheels.
    Last edited by JayC; 06-01-2016, 07:25 AM.

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  • CraigAustin
    commented on 's reply
    You like math so you must know Jacobi. Take his advice and always invert. On a normal road bike I can exceed 30 mph on pedal power alone. The BBSHD might get me another 8mph on that bike, so who's doing most of the work? Well you say, that last mph requires much more power than the first 30. True, but then, if the motor gets me to 30+ and I can pedal it up to 38?

    Here's another construct: I'm commuting, not racing. My speed comes in bursts (think sprints) to keep up with cars between lights and stop signs. I couldn't pedal that hard for an hour, nobody can, and my battery would last 15 minutes at that pace anyway. Comparisons to tour riders over long distances make no sense.

    I get the numbers, no rider can match a motor. I'm just saying think before you write. If I want to know about Cyclones, or how to go 30 mph in northern winters with black ice, I'm coming to you. But there is much you don't know in the world of pedaling your @ss off.

  • gman1971
    commented on 's reply
    That would explain a lot of things... and Craig must be really fit too... going over 30 mph if the motor is not doing all the work requires good physical condition. :)

  • Eric Luna
    replied
    I have both the bbshd and the cyclone....and for some reason the cyclone has a higher top speed and the power comes on stronger....even when on a battery limiting the power to 30 amps.

    I have not figured out why... i think it might be limits in the controller...but its hard to get the bbshd much over 30mph without pedaling your ass off like some other poster said....where as the cyclone can hit 40...somehow an unreachable milestone of the bbshd.

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  • gman1971
    replied
    Originally posted by CraigAustin View Post
    Jesus man, take a knee for once. No one doubts your grasp of electric power theory, but there are things you just don't know because you were building model airplanes while some of us were playing sports at a high level. Watching TDF races with color commentary is not the same thing. I appreciate all you contribute here - some of it is truly fascinating - but stay in your lane when it comes to cycling knowledge. The difference between 30 and 35+ is a big one for commuting around here, so pedaling is not pointless at all.
    Why would take a knee? I am simply stating my findings while being civilized and not being confrontational, nor calling your findings BS, in fact, if you read carefully I agreed with you that what you're stating is, in fact, doable. Building and flying RC large scale helicopters is not relevant to this matter, so I don't see why you brought it up here, maybe to demerit my response?, while also assuming that I've never done any kind of sports at any higher level? What about 40 meter dash at 3.9 seconds? That was over 20 years ago, and I can probably still take you at a 40 meters dash today... I used to train as a 100 meter sprinter; but regardless, all that stuff is irrelevant to this matter. Old glories don't mean anything as I am not a teenager anymore, nor I actively train beyond the casual ride. But the fact remains that those TDF riders are capable of 415-450 watts output for 1 hour, sustained effort. And probably close to 1700 watts peak for a few seconds. So yeah, to reiterate, 1700 watts IS very relevant to get to 36 mph, but not sustainable. Most normal untrained people are 100-150 watts output, you could be a 250 watts, 350 watts, I don't know, and that makes a huge difference on what you can deliver over a few seconds peak as well. Your bike can also be super aerodynamic, very light and you could be riding aero-bars too... all that makes a huge difference. So without hard data to compare we are simply speculating how much you can peak, how much the motor is doing and therefore not possible to draw any conclusions.

    All I know is the data recorded from my Cycle Analyst, which again its not the same as what your case would be; and the power required for my my eBike on "mostly" flat surface to get to 36 mph on my Cyclone 3000W eBike is around 1600-1800 watts... give it a 10% efficiency loss so the motor is putting out about 1400-1600 watts, and another 5% loss at the drivetrain and you have ~1300-1500 watts at the wheel. Then, in contrast to those numbers, the trike is about 800 watts to get to 30 mph, so yeah, the trike is much easier for me to get to 30 mph than it is my eBike.

    G.

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  • CraigAustin
    replied
    Jesus man, take a knee for once. No one doubts your grasp of electric power theory, but there are things you just don't know because you were building model airplanes while some of us were playing sports at a high level. Watching TDF races with color commentary is not the same thing. I appreciate all you contribute here - some of it is truly fascinating - but stay in your lane when it comes to cycling knowledge. The difference between 30 and 35+ is a big one for commuting around here, so pedaling is not pointless at all.

    Leave a comment:

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