How many pound thrust for good acceleration?

[cwah]

Hello there,

I'm going to buy the mac motor from Cellman (probably the 7T) and I'm wondering how much pound thrust I'd need to have good acceleration on a 16" wheel?

The BMC_V2 is the closest motor to the Mac 7T:

I'm planning to keep low amperage (around 25-30) to preserve my batteries.

What does 85 lbs thrust mean? Is it good acceleration?


ps: I'd like to have enough to do wheelie and start as fast as a moped/motorbike. lol :lol:

 

[dogman dan]

You'll outrun a moped off the line for sure. I don't know about the wheelie though. You can pull a wheelie anytime on a light bike though.

A 7t mac in that small a wheel is bound to giddyup. You'll really know you are there if you see a rear tire spin, but I doubt you'll get that unless you really watt up.

 

[cwah]

Thanks Dogman, how many amps, volt and with what motor do you use to have good acceleration (wheelie)?

I'm going to check that on the simulator lol

 

[liveforphysics]

This much is seems good to me.

[youtube]NCpzXIPXdAQ[/youtube]

 

[neptronix]

If you are going for wicked wheelie power, forget the geared motors, unless you want to run one in a 20" wheel.. maybe you'll get wheelies .. if you're light.. :\

Go straight to Crystalyte HT/HS, magic pie, Clyte 53xx, Clyte 54xx, greyborg Hubzilla, or a scooter motor ( need to fab 180-200mm custom dropout section though ).

Above list is in order of how torquey the motor will be. The smaller the wheel, the better the result.

 

[Brentis]

Torque is relative.
This is H3540, 16s5p a123 26650 Cell_man Pack @35amps in a 20" (406) wheel.
72ftlb trq. plenty on a commuter bicycle of 330lbs gross weight.
[youtube]x-IzxWa_y-w[/youtube]
.

More is always better though :wink:

 

[Brentis]

Thanks Dogman, how many amps, volt and with what motor do you use to have good acceleration (wheelie)?

I'm going to check that on the simulator lol

Wheelie'ing is a technique. All about weight placement & power input.
You need very lil' power 100w or less,with the right bike and rider capability.

 

[neptronix]

[youtube]SoAnGuGAK-s[/youtube]

This is definitely in the 70-100ft-lb zone.

I had to move the seat as far forward as possible and lean on the front to prevent being thrown backwards.
Good enough for me, lol.

 

[cwah]

This much is seems good to me.

[youtube]NCpzXIPXdAQ[/youtube]

I'd looooove to be able to do that with my bike lol. But I'm only having a commuter bike so it's still lightweight without drawing too much amps

 

[cwah]

Torque is relative.
This is H3540, 16s5p a123 26650 Cell_man Pack @35amps in a 20" (406) wheel.
72ftlb trq. plenty on a commuter bicycle of 330lbs gross weight.
[youtube]x-IzxWa_y-w[/youtube]
.

More is always better though :wink:

With my configuration, I should have more because it's a 16" wheel. I'm at 85 pound thrust!! Hope it's going to be high enough for wheelies.

Actually I don't want to wheelie, but to have enough torque to wheelie automatically :lol:

 

[cwah]

[youtube]SoAnGuGAK-s[/youtube]

This is definitely in the 70-100ft-lb zone.

I had to move the seat as far forward as possible and lean on the front to prevent being thrown backwards.
Good enough for me, lol.

Oh, just read it's 70-100 pound thrust.

I'm going to have 85 pound thrust now with my bike. Is it enough? :lol:

 

[Brentis]

I dont think you should do what I did, a brake burnout, with a geared hub.
D.D. are probably more tolerant to this type of abuse.
Just a hunch though, I couldn't attempt that with the geared hub Ive run.
16" wheel does create alot of torque, it surprises me, the dramatic rise in torque, as wheel shrinks.
Singing to the choir.(see sig.)

 

[neptronix]

The definition of 'enough' is very, very relative

By the way, cell_man has warned against using the BMC and MAC motors in a 16" wheel. The electrical RPM becomes a problem for the controller eventually.. which ends up limiting your top speed.

When you place your order, ask him.
You may be better off with a DD hub in a 20" wheel.

 

[gensem]

Get a greyborg hubzilla and start with 180 pounds of trust in a 20" wheel with only 5kw of power!

 

[dogman dan]

As others said more clearly, you can pull a wheelie pretty easy. A bike that flips you despite leaning on the bars and flings shoes takes more power. More than you'll get from a Mac. But a few watts into a mac and you can pull a wheelie that looks good, and outrun a moped.

You want motorcycle power, you'll have to go monster hub, or a real peppy chain drive.

 

[cwah]

From the simulator, with my configuration to the maximum at 74V and 40A, I should be able to have 150 lbs of thrust with only 2600W!!! That's certainly because I've a 16" wheel. :lol:

That should be enough for super wheelie. I'll have to learn how to not do wheelie under acceleration :lol:


ps: from your answers, good acceleration means 100+ lbs/thrust. So that's my minimum I suppose

pps: I already asked Cellman, he did some test and apparently with the new mac motor stator it should be ok even if it produces more heat.

 

[neptronix]

Really? he OK'd it in a 16" ? this must be new.
The new stator is different - it supposedly produces slightly higher speed per wind. It's supposed to handle a bit more power too.

Nobody's got one in their hands yet though. We shall see..

 

[MadRhino]

What is good acceleration for you?
That is the question.

Enough to start ahead of the cars in town?
Enough to race motorcycles?

Enough to jump a park bench from standstill is my answer.
I need to build more. Next year I'll be close.

 

[cwah]

The problem is that I don't know yet what's a good acceleration for me.

So for now, I'd just say "the higher, the better".

But I still need to have a commuter bike (no heavy motor)

 

[Toango]

Im surprised a ebikekit gear motor on my 20" folder with a 12 controller can pop wheelies and has good acceleration. More so than a 7 t mac than i currently run. Its lighter stealtheir but only goes 20 mph which is ok. But the mac 7t can go 27 mph

 

[cwah]

Toango, I think it's because you have a high torque version for the ebikekit gear motor (it can only go up to 20 mph) and a high speed version of the Mac motor (7T at 27 mph).

If both motor would have the same top speed for the same voltage (same winding), I believe the mac would have better acceleration because it's bigger.

ps: That makes me think I'd probably need to buy a 8T mac motor for good acceleration (rather than a 6 or 7T.) because you don't see that much acceleration on a 7T.

pps: On my brompton, I have a top speed of 30 mph on 74V8AH lipo. But the problem is that on acceleration I'm using sooo much watt, around 2500W. (crazy for a little 4.6kg motor ). I think I need a higher torque motor to increase the efficiency :lol: