John in CR's quest for 82mph

[AussieJester]

,
I can hear your sphincter starting to pucker up all the way from here.

I think your confusing the 'sphincter pucker' with hysterical laughter John...From what i can tell you lerant nothing from Luke and its obvious now why you didnt want turns in the 'race' Like me to email you some trail for those forks buddy? They will flop side to side
quicker than the legs on those CR hos mate.

all you would have ever seen was an ugly ass ebike for shuttling the kids to school.

And this bike differs how exactly?

Luke came back from every ride down with a big ole shit eating EV grin,

not surprising really, its the only e-bike hes ridden he didnt have to push home after ridding it

KiM

EDIT:

Here's a quick photochop for you Johny Boy to showz you approximately how it should be to get any sort of handling.



Theres 2 ways to achieve this i leave you to work out what they are In its current guise you will definitely need all those Jedi skills of yours, (we shall call you Jedi John i think .. ) what with the frame geometry and the likely crab walk the bike will have as a result of being built without a frame jig i think you will find out in a hurry what a tank slap is and why we wear helmets
++
*TIP - when the tank slap starts lean back and give it full throttle and get all the weight off the front wheel whatever you do DON'T shut it off

 

[John in CR]

You guys can laugh all you want. My blue bike has wheel flop too, but is dead steady at any speed. Of course, you can always put your money where your mouth is.

BTW, the head tube angle was more slack than I wanted. My buddy thought he was helping and got carried away and cut through the top tube too much when I had my back turned. Instead of changing it now, I'll give it a go first. If I don't like the angle, I'll cut it off and weld it back on differently. It will be a learning experience regarding the effects on handling, since I haven't been that slack with a head tube before. Keep in mind that I have at least an inch of trail adjustment in my clamping front dropouts.

AJ,
The difference is that you got to see under the hood ahead of time, but please do keep up the talking. It'll make what's coming that much sweeter. 8)

 

[John in CR]

AJ,
Your lesson is erroneous. You have to draw the line through the center of the headtube, not the forks.

It's a bit difficult to tell right now with the angle of the photo and the fact that the front motor axle is only partially seated in the left dropout and isn't attached at all on the right side because the brake drum housing hasn't been removed yet. The contact patch is pretty accurate, as is the line through the head tube. I eyeballed that early on and the trail looked like it was going to be in the 4-5" range. That's why I didn't worry about redoing the head tube angle at the time.

 

[AussieJester]

Appeared to me the forks were slightly angled to the right and when straight they were lined up on the head tube hence the line i drew, either way though buddy they are miles out, easy to see stand the bike upright and sway it side to side an inch the forks will flop if
they are free at the head tube. When correct they will sway from side to side but not flop, can video mine to show you if i haven't
explained this well...? You can gain more trail by altering the lower fork crown or adding longer drop outs, which i dont think is an option those are die cast forks arent they?

Heres a diagram showing the adjustment methoids

AJ,
The difference is that you got to see under the hood ahead of time, but please do keep up the talking. It'll make what's coming that much sweeter. 8)

LoL..yeah and the 69 page worklog of mine revelas nothing JJ

KiM

 

[Arlo1]

You should probably run a lewer for leg brace it will keep both sides squared up alot better reducing hi speed wobbles!

 

[AussieJester]

You should probably run a lewer for leg brace it will keep both sides squared up alot better reducing hi speed wobbles!

Could we have that again but in English this time please?

I don't follow what your getting at with (i presume) a 'lever?' for a leg brace...can you
elaborate a lil more please buddy... cheers

KiM

 

[John in CR]

"Reduce"??? If I encounter ANY high speed wobble the geometry gets changed that day.

Thanks AJ, I understand the things that can be changed. What I lack is the experience of "feel" for what all the changes do. EG I didn't like the way my blue bike handled at all at speed with the original head tube angle. It was downright twitchy if I bent forward to duck under a strong headwind. I cut it off and raked it back a good 10-15° more, and it's great now, except that you have to keep a hand on the handlebar when stopped. I've had it up to 97kph tucked low and forward without a hint of instability in any position.

News Bulletin for you and Hyena: Out of curiosity I just went and measured. My blue bike has a trail of 4.5" and the new frame has a trail of 4" despite a more angled headset. That's because the offset of the forks from the head tube is much greater with the motorcycle headset I'm using. Also, there's not going to be any "crab walking" either. The frame is dead on true, and both wheels will be on the centerline of the frame and aligned in both the horizontal and vertical axes. IOW some people need jigs and some don't.

Keep them coming though. Maybe you'll hit on something I can use.

John

 

[AussieJester]

IOW some people need jigs and some don't.

Your a better fabricator than i then gungadin...just trying to help
seems you have it all under control :lol: :: sits back an watches in silence ::

KiM

 

[enoob]

improperly setup rake and trail can be a ride ender John not just a go to the shop and change it deal

high speed tank slappers are not fun and with 100mi of battery, 2 motors all on a custom frame youve got some work to do

rake and trail are tuned to work with the bikes weight distribution and transfer under load to get the desired turn into a corner . the worst tanks slappers ive had never even showed up till over 120kph and then it was only leather that saved my skin

since you dont know your weight bias yet it may be an idea to work on mounting batterys and the rest first

after that its not just the head tube centre line you need to worry bout . the fork centerline is just as important

 

[Arlo1]

You should probably run a lewer for leg brace it will keep both sides squared up alot better reducing hi speed wobbles!

Could we have that again but in English this time please?

I don't follow what your getting at with (i presume) a 'lever?' for a leg brace...can you
elaborate a lil more please buddy... cheers

KiM

A brace that clamps both lower fork legs togetther Here is a link http://www.angelfire.com/mb/MiniMoto/YSRforkbrace.html to one for a ysr50 and a picture of another brace it self.

 

[AussieJester]

aaaaaah gotcha Arlo1 cheers mate excellent idea
would prevent any fork twist. Cheers for explanation mate

KiM

 

[Arlo1]

aaaaaah gotcha Arlo1 cheers mate excellent idea
would prevent any fork twist. Cheers for explanation mate

KiM

No problem man just want to keep you ripping in a somewhat safe manner!

 

[John in CR]

Am I underestimating the issue, or are you guys just being nervous nellies for me? I'm more concerned about my wheels being properly balanced.

I've actually changed the rake very little from the motorcycle the headset was on. Here's the before and after, with the before on the right.


I never liked riding motorcycles fast, so this is just for a one time shot probably in the 70's. Typical riding will max out at 50-60mph, and I have zero interest in exceeding 80mph except as a one time shot to hit a mark, and that will be on flat straight road. I may take it on some mountain roads later, but it won't to to ride at the ragged edge. Instead it would just be a leisurely cruise carving along a nice smooth winding road over the mountains. Where I'll take advantage of the performance of this beast will me showing off on takeoffs, especially when scooters and motorcycles are around, but otherwise performance riding just isn't my cup of tea. That shit is dangerous and really does require full protective gear, since even the best pro riders hit the ground all the time doing that stuff.

 

[liveforphysics]

The geometry will be fine. You're not trying to win a GP race with it, that minor rake will just add some high speed stability at the cost of a little low speed maneuverability.

Get it rigid with an extra brace or two here and there after you get the battery layout figured out, and you're going to have a monster on your hands. I think you will have a higher top speed than all the non-hubmotor and hubmotor e-bikes out there currently. Which means I'm going to have to re-gear, and we gotta get recompence to re-gear the trike and see if he can get a 100mph pull on her.

I can't wait to see what a monster this thing is!

-Luke

 

[John in CR]

Thanks Luke. These guys were making me start to worry a bit. The fork brace does look interesting if I have any issues. I'd think with so much higher than normal weight on the forks that off center bumps and stuff could create extra flex. I'll just fab one that doubles as the mount for a fender.

John

 

[Arlo1]

I'll just fab one that doubles as the mount for a fender.

John

Thats what I did with my Z50 thats got longer forks and rear shocks and is now a 75cc lol! But it works great.

 

[enoob]

now obviously i know this is a lil more extreme than what you are planning but take a look . these guys are not going that fast and the guy puts the front end down ok at first .

ive had an incredibly similar experience on a 1992 vfr 750 that was going round 120 130 kph after having the front end tore down and rebuilt it had been done incorrectly . good thing i was just feeling it out or that day would have been real bad . the kicker ? i never lifted the front end in mine i was just getting confident of the rebuild that i was gonna try it next. wieght transfer compressing your front end changes things and if your setup is close to the edge before compression , what comes next is bad.

what to watch for is how the wobble gets real bad once the forks have compressed and at that point its like having the brakes on making it impossible to get your weight of the front end and end the wobble.
http://www.youtube.com/watch?v=bK7KYNwX6Lc&feature=related
if your geometry is incorrect and after a good bit of accelerating you lift juuuuust hard enough to overload the front it could be bad . you will want to learn this stuff ( lord knows i dont know it)
http://www.performanceoiltechnology.com/rake_and_trail.htm

and take your first few rides with great caution . slowly testing how hard and how fast you can transfer weight to the front end

 

[Arlo1]

I wouldn't worry about the front end to much. The more rake you have to more stable it is at speed as a rule. You have lots of rake I would just think of it like a chopper and alot of them rip along up to 100mph with perfact stability (kinda like riding a couch) The other things with the custom chopers I help guys build is there is NO prescision in their work they just whip up a bike and dont worry about the rake and trail as long as it has quite a bit they are fine!

 

[deecanio]

talkin of wobbles .... http://www.youtube.com/watch?v=54fTFm5Dc-I&feature=related

D

 

[John in CR]

I don't have any intention of lifting the front wheel, and yes of course I'll be taking it nice and easy till it proves out. I want to get a good feel of the 2wd handling too. The only times I've encountered instability, sitting more upright and back (ie moving the CG upward and rearward, with upward slowing sideways movements) was my instinctive reaction, which was effective, so I seriously question trying to move my weight forward as a cure. It's not like the weight will be so rearward to make the front end too light. The front wheel and motor assembly weighs almost 30lbs.

Actually, as far as weight and geometry are concerned, my limited experience is in direct agreement with Luke and Arlo, as well as that performance info linked by Enoob. My only concern about weight, CG, geometry, etc is that battery weight at the bottom of the frame in front of the pivot and BB. I know low and rearward is best to minimize weight's effect, but I've never had weight low and forward like that, so I need to get up to 30mph or so and give the handlebars a wiggle to feel the effect of weight there. The group that looks at a bike as rolling around the axis of CG in turns would certainly predict that weight will act like a pendulum, but since bike turns are more complex than that, I'm going to have feel the effect to fully understand it. I think it will make the counter steer feel a bit sluggish as the lower front of the battery will have to change it's direction the most, so momentum will resist it. Then as the turn starts to take place, how will it feel to change direction the other way when it's not part of the turning wheel. Weight low and forward in the frame being a problem may be the one thing that good ole Safe was actually right about.

John

 

[John in CR]

Shoot!!! Test run tomorrow is out of the question. I've got a clearance problem for my disc brake mount. I'm ok between the front dropouts, but they're centered on the fork end and 22mm wider than the space between the fork tubes. Oh well, my nice thick AL disc adapter will have to go on a rear wheel install. I'll just make another out of steel but thinner. I'll do the same and make it to fit the remnant lip left from the original brake drum. My plan is that the plate will reinforce the motor side cover. Then I can go very large with my air intake holes there. I want large enough with the holes so I can screen the intake and still get plenty of air flow. That can't be done without reinforcing the cover, because on hub motors the side covers bear the weight of the entire bike and all of the shock loads.

Here's the 20mm culprit. The slots are the exhaust for the centrifugal fan action that will keep the motors cool.

 

[John in CR]

Double shoot! Clearance issue with the motor, even with a 203mm disc. I have to go giant and attach directly to the cover ala Hal 9000, so I'm waiting on a 280mm stainless disc to become a brake rotor. It's cool enough that I ordered 2. Oh well, the additional week gives me a chance to work on some other stuff, including how to enclose the batteries without creating a big flat wall to present to side winds.

 

[Hyena]

That's a big ass rotor! What are they off ? Motor bikes ? I may have missed it earlier bur are you using the original motor bike calipers /brake system ?

 

[John in CR]

That's a big ass rotor! What are they off ? Motor bikes ? I may have missed it earlier bur are you using the original motor bike calipers /brake system ?

I'm sticking with hydro bike brakes for now. The disk is just a doughnut of stainless steel 11"OD 5"ID, which will bolt directly to the hub motor cover. I ordered 2, in case I mess one up ventilating and lightening it.

Hopefully regen braking works fine, making the mechanical brakes do only a small portion of the work.

I got good news today regarding some nice thick planks of balsa, so my side covers will be carved into whatever shape I like. I'll seal, waterproof and harden with epoxy. This may turn out cooler than I was thinking. 8) 8) 8)

John

 

[John in CR]

I can say with some confidence that an electric bike will definitely surpass the 81mph human powered speed record with me aboard, and I won't have to get inside a lima bean on 2 wheels to do it either. My secret weapons are in route, 12 fet and 18 fet Lyen controllers with 150v fets.