New 24' slopestyle freeride build, getting serious!

Is it 35-40 loaded or unloaded? I am also quite fond of technical offroad stuff, but I usualy ride 20-35kph stuff as i'm not so good at trials riding!

The sensorless controller I use is quite fast to react, and as it is starting to rev the motor unloaded, should get pretty close to sensored startup. Of course the clutch adds quite à bit of delay in the system, but it starts to engage at about 100 rpm. Time will tell?

The sbp order got shipped last nigth, i'm not sûre about what kind of delay to expect to Europe?
 
bzhwindtalker said:
Is it 35-40 loaded or unloaded? I am also quite fond of technical offroad stuff, but I usualy ride 20-35kph stuff as i'm not so good at trials riding!

The sensorless controller I use is quite fast to react, and as it is starting to rev the motor unloaded, should get pretty close to sensored startup. Of course the clutch adds quite à bit of delay in the system, but it starts to engage at about 100 rpm. Time will tell?
I am watching your build closely to see how well you do get on with a clutch and a sensorless controller , it just may do the trick. The delay can be gotten used to as long as it consistent. The 35-40 is loaded. All that 100 rpm before engagement means that you will have to be more creative with your technical riding and think things though a little more ( less room for error ). You would have to ride like the old days when you were not allowed to stop and balance within a section ( non-stop trials )
 
I was actually thinking of a trials mode, where the motor would be spinning just below engagement point whenever a switch on the handlebars would be on. Some resistors on the throttle line and a potentiometer to dial the rpm right should do the trick. at this point I might as well bite the bullet and fit some halls :/
 
sn0wchyld said:
Whiplash said:
Just use a two stage chain box? I bet you could modify the double row box to be two stage and get 9:1!
I was actually thinking of using 2 boxes put back to back, that way you keep the double chain strength but get a 9:1 in one unit. efficiency might be a bit sucky though.


I think the efficiency would not suffer as much as the out and out size and weight. Most chains are around 95ish% efficiency if I recall correctly so that is not really an issue, I think it would just be too wide....
 
Two units back to back might actually be a nice solution, I might try that one day or another!

This bike does quite well without motor :
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I was hoping to get my order from sbp today, but I had no luck unfortunately... I can't wait to try this bike with some power. I tested it on pedal power only, it is really heavy, but still quite ridable. The forks will need some tweaking, they are too soft for the added weight and lack some damper I think. I still got some work done, securing the unit to the frame and making a top panel :

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allrigth, T8F is worthless :x I have no idea how, but i managed to snap a link.
The whole drive is waaaay too noisy, the motor mount flexes under load, even the frame is flexing actually!!
I did not get the cranks yet, so i just screwed the fw on a bottom bracket cup.

Few thing I learned from this build :
the bmsbattery 12 fet sensorless spins a 180kv motor at full rpm
T8F is crappy as hell
pocket bikes cluchs smoke a lot when stalled at 1500w input :twisted:
clutches are inefficient
I want a mid drive hub pushing 1000-1200w
I'm bored, I just want to ride...

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wtf chain
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I hate being bored with builds.

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I will cut and weld back the lower support to gain some clearance and grind the flanges of the hub too, but it looks like it will work. :p
 
Cool :)

It's neet to watch you trying so many different things! What is that hub? direct or geared?

Later,
Jay
 
NOW your talking! I really want to try a DD hub on my bike but its too short of a wheelbase for it, it just won't fit. Your gonna LIKE this now! Wait till you try to climb something the torque is INCREDIBLE, mine is like a real gas dirtbike up to about 10MPH!! Really, no joke, its about as torquey as my old KX 125 was in low gear, So when climbing it will go up just about anything you can hang on to and get traction on, the only limit seems to be when you flip backwards! So if you push any kind of real power through that big hub, its going to be insane! plus you can gear it to do like 55MPH in top gear! Mine is only supposed to go like 20-25MPH if it was in the wheel, maybe slower and I can get it to do 35-36MPH in my "overdrive" gear!


Getting the chain line setup to work is the tricky part unless you just get lucky. I had to make a few spacers on my lathe for the various chain rings to get it all to work together.
 
It seems like you could mount the batteries under the downtube no? right in front of the motor? It would certainly make the bike more comfortable when riding, unless the forks compress too much?
 
I am not too interested in anything above 30mph, but i want insane torque and good control below 15mph.
The chainline actually look quite straigth! But i need some clearance for the chain on the motor side. I also need to secure a wide bottom bracket, because the pedal does not clear the motor on the left side.

The motor is à DD conshimotor with a 32mm wide stator. It just need à phase upgrade and a fresh coat of paint.

I will probably get another frame on the bay, for when the set-up will be relyable. This one is quite beaten already from my experiments!
 
I'm not bored anymore. Mid drive hub FTW

I cut and welded back on the lower arms, the clearance is now quite okay, I will probably cut the flanges off if I am motivated enough !
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The motor mount will get a fresh coat of red antirust paint, and hopefully I will be able to find an extra wide BB in some shop tomorrow morning... 3 day weekend coming with good weather, I want to hit the trails! I still have 2-3hours of work to get it running, as I need to wire back the hub and the halls, plus getting the clearances right. I need +5mm on the drive side and +10 mm on the other side.
 
Sweet! That frame is perfect for that style of mount! The challenge I had was making it fit most if not all bikes, but I think I have most of the common styles covered! I can't wait to see how it runs! Get video of some hill climbing. I think you will be surprised!
 
yes, I tested the bike this morning, nothing to say, it's perfect! tops out at about 65kph, incredible torque in first gear, silent. I am running sensorless because I did not want to go trougth halls sequences, and it works like a charm. it feels quite strong on only 1800w peak, I like to know that this motor can take 10k brusts :roll: I have a hua tong 18fet under hand too for when i will be ready :)

The acceleration feels less than on my 80-85 bike, but it had 4kw geared for 35km/h. But this one will climb any hill where I can stay on the bike with no initial speed :mrgreen:

videos to come!
 
I did 450wh of testing, it all works well BUT the frame is flexing under load and there is still some chain issues.
I recorded a peak power of 2200w, max speed of 65kph (on flat).
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I am editing the videos right now!
 
Awesome! Im telling you, its all over for the RC motors once some more people build this type of bike. Its just so cool having huge climbing power AND the top speed of a nice hub combined with the simplicity of one as well. I know I will never do it any other way..
 
Whiplash said:
Awesome! Im telling you, its all over for the RC motors once some more people build this type of bike. Its just so cool having huge climbing power AND the top speed of a nice hub combined with the simplicity of one as well. I know I will never do it any other way..

Hmmm... I think rc motors still have some life left. I propose an all-out hub mid drive vs rc race!! Super moto style, with some off road and some on road. Maybe we should limit the battery current/capacity too, so it will be a contest of efficiency :p

But I gotta say, both of your guys bikes sound pretty fun...and are probably a lot quieter than mine as well. I bet you could have a ton of torque with a fast-hound hub and high gearing.
 
My bike weights 32kg with 16s 10ah headway, it would probably have weigthed 3-4kg less with a RC drive, but I think it has more potential with the hubbie. I'm all for a race dirt tracker style :p
Videos are coming out quite well!
 
bzhwindtalker said:
My bike weights 32kg with 16s 10ah headway, it would probably have weigthed 3-4kg less with a RC drive, but I think it has more potential with the hubbie. I'm all for a race dirt tracker style :p
Videos are coming out quite well!


It looks very good, but its a shame that the rc didnt work out for you,

Whiplash said:
Awesome! Im telling you, its all over for the RC motors once some more people build this type of bike. Its just so cool having huge climbing power AND the top speed of a nice hub combined with the simplicity of one as well. I know I will never do it any other way..

as regards "its over for rc motors" na dont think so :mrgreen: you have all the benefits of a mid mounted hubby going through the rear gears but at a fraction of the weight and cost , my first rc bike was only 19kg and the one Im working on now will be about the same and hopefully nearly silent , except for the dam freewheel I got, its a clicker :( ,
 
No offence Gwhy! :) it'll never be as quiet, but maybe close!
 
That bike looks amazing, windtalker. Bet the torque is awesome.

The entire frame flexes, not just the motor mount?
 
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