High torque set up needed

[o00scorpion00o]

The 8T on 60 volts gives me 40 mph and super torque, so the 12T, while slower should pull like a train up a hill even pulling a heavy load!

I'm really leaning towards a 12T at this point... do you think it would be able to handle ~2kw for 15 minutes straight at 67v30A or am I just going to fry the clutch/gears? I could also run it at 52v40A, but am afraid that might be a bit slow. I climb a fairly serious hill, but want to go as light weight as possible. Thanks for your opinion!

The 12T would be better for lots of steep hills, I'm sure it could handle 2kw for 15 mins no problem. I never had any problems with my 8T with heat with bursts of 3500 watts and high speed cruises at 35-40 mph. Pulling about 2200 watts for 10-12 miles straight! And the windings of my motor still look perfect. The 8T is a monster hill climber so I can only imagine the 12T being much better, and better for slower speeds!

Cell-man is testing a new clutch to be more reliable so I would wait until that is ready, he is also installing a temp sensor maybe by request only.

I think you are much better to ask cell-man about running the 12T at 60 volts. I ran the 8T far above the recommended power levels and killed the clutch and keyway, but I've the new design clutch on the way and a new axle and keyway, so hopefully all will be sorted to be able to handle the power!

[pwbset]

The 12T would be better for lots of steep hills, I'm sure it could handle 2kw for 15 mins no problem.

That's good to hear. I climb a little less than 500m in about 5.5km and would like to do it at 35kmh or so. I think a 12T at 67v30A should be right around there if my math is right (which it rarely is haha). 10T maybe... we'll see.

Cell-man is testing a new clutch to be more reliable so I would wait until that is ready

Good to know. Will email him. Thanks again for the info. My last Clyte 5xxx build was awesome and easily gobbled up to 8kw bursts, but man-o-man was it heavy/overkill.

[dogman]

I would think 67v and 30 amps would be a bit harsh on a Mac. Not wildly too much, but you'd want to watch temp for sure.

How long you flog it makes all the difference, but for sure a 12T mac should climb like a goat. Fast won't be happening, but at 67v it should be tolerable to ride.

[o00scorpion00o]

I would think 67v and 30 amps would be a bit harsh on a Mac. Not wildly too much, but you'd want to watch temp for sure.

How long you flog it makes all the difference, but for sure a 12T mac should climb like a goat. Fast won't be happening, but at 67v it should be tolerable to ride.

At 2100-2500 watts the mac 8T will last a long time and if the 12T will be going up hills a lot, then that should be no problem for it.

I've never had a problem with the mac on steep hills, but it wasn't bogging down and I got up them very quickly.

[o00scorpion00o]

I really would ask cell-man to install a temp sensor, you will always then know if you are pushing it too far!

I would hook it up to this

viewtopic.php?f=3&t=22919

It looks a very good piece of kit!

Or wait for the new cycle analyst, that will have the facility to read temperature!

[dogman]

Yeah, most of your ride is not usually going to be pulling nearly that. I've just learned the hard way with my slow winding 9c's, About the time it's hitting 80F, I ditch the 72v 40 amp controller. On 72v 20 amps, seeing real world 1500w on a CA, I don't worry about riding hard in desert heat all summer. A few less amps than 30 would be my plan for summer, say 25 amps. In a way, if 1500w isn't getting you up that hill, then mabye adding 500w would be adding 400w of just heat anyway.

Hard to find that line, on your ride, in your terrain, but 1500w is pretty safe for sure. 2000w is not unsafe, but it's in the zone where you better start actually looking at your temp guage.

[pwbset]

I'm also contemplating a rear 20" 2810 9C at like 84v25A, but I'd want a rear disc brake and not have the pedals hit the ground. Not sure that's doable.

[o00scorpion00o]

I'm also contemplating a rear 20" 2810 9C at like 84v25A, but I'd want a rear disc brake and not have the pedals hit the ground. Not sure that's doable.

For some strange reason, I still think geared hubs are better for slower riding up hills, because the gears allow the motor to spin faster it won't really bog down like a direct drive, so a high torque slow wind 12T on 60 volts should be fine at 30 amps, I would even think 45 amps would be fine for a shorter time, again that's where you need temperature monitoring, and a usb cable for the controller so you can adjust it to better suit your motor, and terrain or both!

The 10T according to cell-man's site says it will do 30 mph on 60 volts, so if the 8T will do 40 mph on 60 volts and the 10T does 30, I think that means the 12T would do 20 mph max on 60 volts ? too slow for me, but it would have train loads of torque!

I think recumbents are far better for small wheels! I would really love one, But I'd be too scared on these roads!

[pwbset]

I still think geared hubs are better for slower riding up hills

Define slow? 20mph with no pedaling up an 8-10% grade for 15 minutes suits me just fine. I averaged 16-20mph in previous summers with DD motors and it felt right, but I was still "assisting" from time to time with even my 24" Clyte 504 cause it could and did bog sometimes if I had to slow down for whatever reason (like elk or turkey crossing the road ). Anything over about 30mph on a mtn bike on these mountain roads just feels sketch to me. I want enough speed to justify the commute compared to driving, but not so much speed that I'm gonna kill myself if I wreck, which I've done before and will do again I've no doubt.

[o00scorpion00o]

I still think geared hubs are better for slower riding up hills

Define slow? 20mph with no pedaling up an 8-10% grade for 15 minutes suits me just fine. I averaged 16-20mph in previous summers with DD motors and it felt right, but I was still "assisting" from time to time with even my 24" Clyte 504 cause it could and did bog sometimes if I had to slow down for whatever reason (like elk or turkey crossing the road ). Anything over about 30mph on a mtn bike on these mountain roads just feels sketch to me. I want enough speed to justify the commute compared to driving, but not so much speed that I'm gonna kill myself if I wreck, which I've done before and will do again I've no doubt.

20 mph is a reasonable speed, but any motor bogging down is bad.

Direct drive motors don't have the same torque as geared motors of the same size though, the X5 motor isn't a fair comparison to a small geared hub. And what makes the geared hub more efficient is it's ability to keep spinning faster than a direct drive would at the same mph and power level!

Sure you can probably dump an extra 20 amps into the x5 but with the geared hub you wouldn't need to in my opinion.

the magic pie is a very high torque motor, and a slow wind and on the same hill the mac went up at 29-30 mph that the pie did at 21-22 mph, same power, controller ping battery on 48 volts. The mac did at 2000 watts what the pie would have needed closer to 3kw to do the same mph up the same hill.

Now the hill is nothing the pie can't handle, it just didn't have the voltage needed for to achieve the same speed, it has the torque and buckets of it.

But the temperature of the pie was just warm where the mac was hot. But I'm confident the mac could do that hill every day and not burn, this is why I want a temperature sensor to keep track of temps, just in case, But the 10-12T would do it much better, not as fast but would probably be much cooler.



A faster wind pie may have done it, but then again a faster wind means less torque and a faster wind heats up faster on hills as it gets bogged down.

[Matt_ZH]

I took some time before i order. I will order the Mac HP kit 28" 12T upgraded, 12 fet3077, half twist, ebrakes
and a 12S 20Ah A123 pouch pack 39V 20Ah, 80A BMS, a CA plus some additional items from from emissions-free.com. I got a good email reply with a detailed list what i need to buy. As its my first conversion i will buy all the stuff from them.Just they don't have torque arms
The 12 T motor together with the 36V battery will keep me within the speed restriction while delivering sufficient power for uphill.
Cell_man suggested consider to use a front motor. I want to avoid that. However i chose a 80A BMS just in case. The A123 cells should be able to handle to two motors anyway. As the steepest grade is quite short and i also do not drive around with the full weight all the time i will try to keep the bike at speed by pedaling.

@Lebowski
The batteries will ship by DHL, the rest by SAL, so i don't know the exact shipping cost now. I can state the shipping cost plus additional handling cost and duties once the parcels have arrived here.