New freeride project - LMX P1

[dan974]

yes i think you must have your shock tangent to the cercle trajectory, regarding the main pivot, or it won't be linear at all...loi d entree sortie... t as pas des cours de cinematic a l insa

 

[2moto]

bzhwindtalker

If you want, I'd be happy to help you out with rear suspension geometry, using CAD tools that calculates things like progression ratio, linkage ratio, linearity, etc. I do this regularly for motorcycle and bicycle racing builds. You'd need to supply the measurements as indicated in the marked up picture below.



Or, stated in words I would need:
1. Fully extended length of shock absorber
2. Maximum amount of shock travel
3. Length of swinging arm
4. Height of shock mounting eye, vertically above swinging arm
5. Distance from swinging arm pivot to vertically below the shock mounting eye, along the length of the swinging arm
6. Vertical height of motor axle above the ground

The output from this analysis includes graphs such as this:

 

[bzhwindtalker]

Hehe i'm not too bad a cinematics usually!

2moto, thanks for the offer! I will take some mesurements on the current configuration, however I will probably make a new swingarm with better triangulation, as this one is quite heavy, so maybe you could help me out in the suspention design of the new one?

I found a solution for bearing supports and that's how the geomety looks in the crurrent configuration :

 

[2moto]

I would really try to put the swinging arm pivot inline with the motor sprocket and the rear axle, when the suspension is at half travel. They way you have it will tighten the chain up considerably as the suspension compresses and the slacken of considerably when you compress further. Not a good scenario. You want to try to minimize chain tension variations through the entire suspension travel.

I would put it pretty much where you showed in the previous picture AND reduce the swinging arm angle at full extension, i.e. move the upper shock mount up and forward.

 

[dan974]

you should follow 2moto, as I 'm not and expert, I think he gots stuffs to teach us...

for me it will more linear regarding the pivot point trajectory on the rear arm...certainly a middle beetween the two extrem positions as the radius change due to the shock travel...a drawing or a simulation under catia or solidworks meca3d might help..

 

[bzhwindtalker]

Hey guys it's been a while but I mad good progress lately, the pivots are still temporary but at least I have a complete frame! The front forks are only there for illustration, I had received a marzocchi 888 but the axle clamps were broken so I had to send it back!
The wheelbase looks a bit long to me but the geomety look OK, and sitting on does not seem too awkward.

 

[Denisesewa]

Hey guys it's been a while but I mad good progress lately, the pivots are still temporary but at least I have a complete frame! The front forks are only there for illustration, I had received a marzocchi 888 but the axle clamps were broken so I had to send it back!
The wheelbase looks a bit long to me but the geomety look OK, and sitting on does not seem too awkward.



Nice Progress !
Whats the rear suspension feel like ? seems to me the rear of the shock should be mounted lower for a better angle ? Anyway, the geo looks very Motocross oriented , should handle good.
Keep it up ( we are waiting for more videos ya know ) 8)

 

[rodgah]

looks awsome....subscribed

 

[bzhwindtalker]

I finnaly machined my pivots...

I really need to build a good jig for next frames because the swingarm is not perfectly in line! But I find designing a good jig is way harder than building a working frame

 

[dan974]

you can CAD design it and use MDF wood panel , easy to cut, and precision should be enough, as some guys made some home CNC this way... :wink:

 

[rodgah]

I 2nd the MDF jig, I have seen some pretty amazing things replicated on crappy jigs

 

[bzhwindtalker]

I managed to get it straigth cutting and welding back. I'ts now quite good! Not perfect, but definitely good enought.
I received the forks, 2006 888's in very good condition, paid 300€. I'm now waiting for the CRF 50 seat I ordered and the 15mm rear axle. Then I will need to find a rear brake line, some spacers and ajustements, footpeg mounts, battery box, wiring and ill be done!

I have exams next week but after that I'm 100% comited to finishing the moto and testing it before the road trip 8)
http://endless-sphere.com/forums/viewtopic.php?f=1&t=51403

 

[rodgah]

loooking great.....

pitty you didnt do your trip through Austria so you could get some testing on the ktm freeride-E :wink: . Wish I lived in europe, I would do the trip with ya haha.

 

[jackjetful]

Yeah we have some realy great e bike manufacturers in Austria! ... Your frame is looking very nice

How much output power do you expect if you rewire your 1000W 9c to delta? and do you want to mke a wye- delta switch or just run the motor in delta?
I am also thinking of rewire my 500W motor or buy a more powerful hub..


greetings from Austria,

Jakob

 

[bzhwindtalker]

I doubled the phase wires on the motor, and permanantely rewired it in Delta. I really need the extra RPM to gear it down after that to get a good eficiency even at low RPM. What I did is similar to runing a very small wheel with a fast motor. I wanted to try that for a long time! Hope it works as planned.

I'm more interested in torque/power brusts so I'm not too concerned by continuous power. I will probably put a bigger motor on the next one, like a modded 50mm stator motorcycle hub (cromotor style). Or I may keep the same style of motor and shave a bunch of weigth on the bike. It will depend on my feelings after riding the hell out of this prototype

 

[jackjetful]

I doubled the phase wires on the motor, and permanantely rewired it in Delta.

Istn't a switch a better option to have higher efficiency? Normaly a motor spins up with wye and after that it will be switched to delta. I didn't rewire a hub motor yet but that's just theory. Do you have any practical expirience with this?
I am just curious because I also plan to rewire my motor for my actual build

 

[jackjetful]

At all I don't think 500W will be enough for my bike. How much weighs your frame so far? ... just to have a comparison between power and weight.

 

[Tinto]

I like how this is coming together. I also think you're responsible for getting a broader audience interested in ebikes through your videos!

I really need to build a good jig for next frames because the swingarm is not perfectly in line! But I find designing a good jig is way harder than building a working frame

This jig looks decent - http://www.flatpackfoundry.com/index.php?route=product/product&product_id=50
Perhaps something to consider if your next bike is using bicycle sized components.
Not sure how well it would work for a FS frame though - most of the frames I've seen in it are the typical barn-door road bike.

 

[bzhwindtalker]

So happy to have finished my exams!
Now let the fun begin :

 

[bzhwindtalker]

Moar pics before I strip the frame down for paint :

I'll be getting my batts and wiring hardware tomorow. I will do 20S 10AH of 4s hardcase, and I may build a second battery later.
I need to find a good way to make battery packs hot swappable. I have a good supply of 150A anderson connectors that I will use for this purpose I think.

 

[Tinto]

Like a boss.

 

[kfong]

Nice job, might be something I have to consider making. I like the idea of a trials type setup using a quite hub motor.

 

[dan974]

WIATING FOR THE TESTS =) what brakes are you using ?

 

[Whiplash]

Looks awesome! If its not too late, you REALLY should cap the ends of those tubes that run transversely, the open end very much compromises the strength of the joint since one side of the main tube is not supported at all! It will eventually fail if you don't do it, I have seen many chassis done this way actually fail in the real world on off road buggies and such, it'll crack first, then come completely off! If its at all possible I'd fix it!

Other than that the bike is awesome and I can't wait to see the performance!!

 

[rodgah]

constructive criticism here, I thought maybe changing the angle of your 'subframe' or seat frame might make it look a bit more conventional.....


or is that the look you were going for?