turner dhr downhill with Hubmonster motor

[jansevr]

currently this build is in the early development stages. i have the bike to be used for the conversion but i plan to do quite a bit of custom work. unfortunately i won't have the time or the money for a few more months. fortunately this gives me time to finalize a design

the bike is a 2006 turner dhr - marzocchi 888 fork, fox 5.0 rear shock

the motor i plan to use is John's Hubmonster. the sale thread and more info regarding the motor can be found here: http://endless-sphere.com/forums/viewtopic.php?f=31&t=46898

because of the extreme power from the Hubmonster, i knew i was going to have to make a custom swingarm extension of some sort. i started off trying to figure out where i wanted batteries, and getting a general idea for everything. because highway speeds are possible with this motor i will also want to address aerodynamics at some point.

these renders were just for fun, with the suspension set very low, drag racer style

i realized that the first swingarm extension i designed was no good so i designed a new one based off of the one John uses with his Hubmonster

i also modeled some different battery boxes and a very large and thick clamping dropout. this time the extension is based off of the existing one and braced on the top and bottom. the point were they meet is were the dropout is attached.

for the next three renders i added new discs: hope saw 203mm

also the brakes are hayes stroker trail

after talking with John and some other people regarding the length and weight of the swingarm i decided to make another revision. rather than having such a long swingarm with a lot of unsprung weight, i decided (with the advice of John and others) to move the pivot points further back so that the swingarm would be shorter and reduce the unsprung weight.
i kept the geometry of the new swingarm relatively the same as the old one because it looked good and made sense to me. the way the bike is currently modeled, there are 12 6s lipo on each side - 30ah of 100v total.

there is still much room and time for design changes - any comments and critiques or input on the bike would be much appreciated!

 

[wannesd]

Very nicely rendered, what program did you use?

2 things that jump out at me:

* your crank arm is inboard of the chainring, don't know if that's on purpose?
* I would seriously recommend you add a diagonal support between the swinarm pivot point, and the upper shoch mounting point, to eliminate any stress and bending (cracking) of the extension from theBB to pivot point

 

[motomech]

I don't get it.
Why not start with a motorcycle, since that is you intend to build?

 

[jansevr]

i used google sketchup for modeling and vray for rendering

i hear what you're saying about the chainring. it is a bit unconventional and probably doesn't make much sense. this was a result of using pedals from an old model, trying to keep the drive line in line and keeping the pedals narrow so the pedaling with the fairing isn't an issue or so the fairing isn't too wide. although i don't have all the proper dimensions modeled, the main problem is that the chain (or possibly belt? ) is very wide at the motor and results in being wide at the crank as well.

thats a good idea about the extra support. this last design was a quick thought still needs work.

the reason i dont start with a motorcycle is because i prefer the advantages of bicycles over motorcycles

 

[motomech]

Bicycles don't have any advantages over motorcycles at "highway speeds".
Except maybe to by-pass registering.
Hopefully, that is not your intent.
The sport doesn't need any more 50 mph plus bicycles that will ruin it for the rest of us.

 

[John in CR]

Pedals can be more comfortable than pegs because they allow changes in leg position.
You can't pedal a motorcycle for exercise or if you run out of juice.
Increased power to weight ratio is always better and motorcycles are much heavier.

As long as someone rides courteously and safely, what is going to get ruined for the rest of you that you aren't ruining more yourselves already?

 

[dogman dan]

Looks like a beauty to me. I keep wishing I had the time and the tools to imitate Johns long swingarm bike.

Only nitpick I see is the knees might be hitting the fairing. So you might need more cutaway on the top edge.

But since I don't live in paradise, It would be an illegal vehicle where I live. I know roads here in the big empty where a cop would be seen at most once a year. Or I could take it to a nice racetrack about 50 miles away.


We have no idea if if would be illegal for a motorized bike to go 50 mph where Jansever lives. So comments on ruining it for others would only apply if he lives where you do.

 

[Drunkskunk]

Looks realy good.

2 things I'd sugest. the first was mentiond.. connecting the back of the frame at the swingarm pivot up to someplace like the shock mount area, to give it the stringth it will need.

The other is the shock mount position. A swing arm is basicly a leaver pushing on the shock, and your ratio between how much the wheel moves up and down, and how much it pushes on the shock is too high. The higher that is, the more force it puts on the shock and frame, and the stronger the spring will have to be to support it, and the harder the shock will have to work to absorb impact and counter rebound.
Typicly a bicycle uses between 2:1 to 3:1 ratios

 

[jansevr]

bicycles don't have any advantages over motorcycles at highway speeds - yet this is mainly because bikes aren't built to handle the speed and there hasn't been many affordable motors that deliver enough power. bikes in general have a lot of advantages over motorcycles which I'm sure i don't need to get in to.

I currently live in Milwaukee, Wisconsin. Although this bike wouldn't necessarily be considered legal, i could get it registered like farfle's bike. it has never been a problem for me (on my current e bike - 92v 60amp hs3540 ) to drive around keeping up with traffic. as long as i don't ride around recklessly, especially around campus - i swear theres 2 cops on every block! the only time I've gotten pulled over was for my rear brake light (battery died the night before). one of the cops asked what my ca, i told him it recorded distance and gave information like speed. he asked if 78 was the temperature (it was december and about 20 F) Hahahha :lol: i told him no and they basically left shortly after that

the fairing might need more adjusting, it will be easier in a full scale mock up. that or ill at least need to take some actual measurements of me sitting on the bike.

I added another brace in the area mentioned and modeled the shock rocker arm as it is from the original geometry. basically all i did was chop the bike in half and add batteries and the controller where the extension is.

this first picture is a screenshot of the bike with a transparent overlay of the original bike halfs

rendering takes a while on my laptop so i didn't want to do this first one over even though the ground is very bright.

 

[John in CR]

Now you're talking. A couple of things. Parallel lines are pleasing to the eye, mine anyway, so I'd try to copy one of the other angles with the rearmost support instead of it being squarish. If you can set it to the same angle as the down tube, it would make the lines really flow. Second, with the feet forward pedals the area under the seat can be much wider. That will give you much more space for batteries and the controllers. leaving the front narrower and sleeker with a lighter "feel" to the bike. It will also make it more lateral rigidity, because you can create a stronger triangle support. Extend that extra width to the pivot too. A wider pivot will make it stronger too. Motorcycles have wide pivots, and bicycles only have narrow ones because wide would get in the way of the pedals. I think that could be more aerodynamic too. Plus it will better match the sharper lines of the front. I love the curves of your swingarm, but they may clash with the existing look of the frame you're starting with.

The alternative would be to do a frame from scratch. If you can pull off the extension and swingarm as rendered, then you can do an entire frame. Then copy what you like and still leave space within the frame more specifically matching your battery needs.

John

 

[jansevr]

good idea with the parallel lines - ill try to play around that and see how things line up and how it looks. i like the idea of making it wider under the seat too. that should definitely help with lateral rigidity and stability as well as handling. the front end of any hub motor powered e bike seems to always be too light. the batteries in the current place are an attempt to try to get some weight on the front end. i might end up moving the seat sightly forward as well. and then maybe i could put some batteries under the seat. low weight is always good as well. a scratch built frame is a possibility as well, but i feel like it will be cheaper and easier to modify this one if i can finalize and simplify an idea.

the original battery compartment held about 30ah of 100v. i ended up adjusting it to fit a larger battery although i will probably never run this much lipo(38 6s are modeled) before i made it larger the seat was too low and the bike just looked off.

i also notice now i modified an old file where the pedal was back on the inside of the chainring...oops!

if this or something like this design ends up being a possibility, more thought will need to be put into how the batteries are removed. i was thinking the bottom piece of the frame could be somehow removable? it would be easy to lay the bike on the side and slide the pack out.

 

[John in CR]

Mine are mounted to a piece of plywood that goes in from the bottom and is part of the lateral rigidity. They haven't been out since I mounted them over a year ago, but I could. I can't imagine the inconvenience guys tolerate needing to remove packs all the time.

 

[jansevr]

i too think that it would be ideal to leave the batteries in the bike but it is still nice to have an easy way to get them in and out when you need to.

 

[The Stig]

Nice improvements! Sub'd!
Now I would just brace the upper shock mount to the back of the seat mount for weight reduction. Could just be with bolt on linkages with one end of the linkage attaching right to the shock bolt.

 

[MadRhino]

You are making the tail too long for proper handling, this will be a dragster to ride straight lines. Look at John's bike, the saddle just a tad in front of the rear wheel is about as much as you want to stretch the rear. After that, you start losing a lot of corner ability and you might find yourself in a situation where you will not be able to turn short enough to avoid an accident.

The best handling is achieved with part of the rear wheel under the saddle, and a steer angle between 69 and 66 degrees.

 

[jansevr]

you're probably right...maybe i will try taking out the last row of lipos and shorten the rear by 6 inches. the turning radius might be high but i think it would corner and handle relatively well. currently it is probably a similar length to an xtracycle which i don't find to be uncomfortable to ride or maneuver.

 

[jansevr]

until i get the rest of the parts for this build, i took apart my old ebike and put everything on the downhill:

http://endless-sphere.com/forums/viewtopic.php?f=6&t=48569

 

[jansevr]

had a bit of time to mess around with the CAD...i wanted to see the bike (now moped/motorcycle) would look with two hubmonster motors. i also made some small changes here and there.

the battery compartment is now 3 6s lipos wide. total of 32 6s or 100v 20ah

i also got rid of the pedals...if this design is ever a reality, there will definitely be no need for them

no renders yet, just exports from sketchup. my roommate is having a desktop built, so soon i will be able to render very quickly

 

[jansevr]

another thing i have been thinking about is using sheet metal (perhaps laser cutting) and making a completely custom frame. i used roughly the same geometry as the past designs with a slight variation of the battery compartment. total of about 44 6s lipo. all the controllers are mounted on the downtube with the possibility of having fans on the inside of the frame.

i didn't really notice before...but the bike is quite small! i have played around with some of the dimensions...i guess more than i realized. the wheelbase is about 57 inches or 144 cm. the standover height (height from seat to ground) is only 24! and still enough room for nearly 6kw of lipo i guess having the smaller tires really lowered the height. it should still be ride-able; although i am 6' 2

 

[jansevr]

a bit of a revision of the previous frame. the battery packs are now more centered and all the same size: 3 x 16x6s 5000mah lipo = 48 6s = 100v 60ah (30ah for each motor ) 6kw of lipo!

hopefully i will have actual renders soon

let me know what you guys think. as far as weight/rigidity/durability - does this look plausible for a frame? also, maybe i should move this thread or start a thread under the motorcycles?

 

[The Stig]

I would extend the seat a bit for a second passenger, and put a 9C or HS35 in the front (I think you can get up to 20% of your torque from the front or something). Looks nice!

 

[jansevr]

i could extend the seat for another passenger fairly easy. however, if i ever used two motors - and one of them was a hubmonster, i feel like they both should be. having two very different sized motors (hubmonster and a 9c or crystalyte) i feel wouldn't work very well. i don't know many of the technicalities of running dual motors, but it would be very cool to be able to adjust the amount of torque or power between the front and the rear. having two motors should make overheating nearly impossible. if cruising at 50mph took 5kw, each motor would be pushing about 2.5kw - this is hardly anything for the hubmonster!

i also did a few renders of the last design:

 

[Animalector]

would it be possible for you to attach a STL or STEP or some other CAD model of the Hubmonster?

Otherwise I think it looks fantastic. it'll be heavy

Andy

 

[jansevr]

hopefully you have a program like winrar to extract the file...i tried uploading the sketchup file directly but it wouldn't let me. if you don't have google sketchup - it is free to download and after that you should be able to open the file no problem.

 

[Animalector]

thanks, I'll see if I can import it into my CAD program..

If not I could always just re-model it myself.

cheers
Andy