build thread: klein mantra hs3540 5kW 70km/h 20" (done)

[izeman]

finished the bracket to clamp the battery box to the handle bar.
aluminium bar: 150x70x15mm.

drilled two 26mm holes,

then cut in half,

the put it in the mill to make all surfaces even,

drilled holes for the screws and cut m6 threads.

only problem left was, that handle bars change their diameter from the middle, where they are clamped from 25.4mm (1in) to 22.x at the end where the brake levers are. so clamping was not even. what i did was take some metal repair epoxy, which becomes very hard and can be drilled etc when dried and put it on the inner sides of the clamps. then attached the clamps to the handle bar and squeezed the epoxy out. let it dry, and i have a perfect fit over the whole width of the clamps.

 

[izeman]

oops. last picture was wrong. these are the brackets prepared to put the epoxy on them. all surface that should not get in contact with the epoxy was covered with very thin duct tape.
got the final result's picture on the other camera

 

[izeman]

here is the pic with epoxy. it sticks really well. i'll see how it will do when attached to the handlebar.

 

[izeman]

this is the finished "plug". the side case was drilled to 26mm and there is no rubber plug installed anymore.
the plug is secured with 3x 3mm headless screws. and the little disc protects the cable coming from the motor.

disc attached

btw: technical details are (c) electricwheels.de - many thanks go to him

 

[izeman]

a first impression. front wheel, and box installed.

looks really unusual. but i'll get used to it. i forgot that the bike will be lower, so i would need to raise the saddle. but this will lower the handle bar - relative to the saddle.

 

[biohazardman]

Nice job on the bike thus far. I really like the ebrake switch and battery assemblies very clean job. On the subject of fuses using one at a somewhat higher than normal voltage in our cases should not cause a problem. I run my 12V fuse at 66V and it actually blew cleanly once so I know it werqs. Higher voltages can be a problem though as the gap in the blown fuse may not be large enough to stop an arc from bridging it. So, things will heat up and burn quick until the gap is large enough to stop an arc from jumping across. I have seen some problems here with fuse holders and fuses on the edge of blowing heat up instead over time and cause damage but as yet I have not seen a failure in this type of automotive fuse being a problem at voltages normally used on our bikes.

 

[izeman]

some updates from the last days - i don't have access to the workshop with all the tools very often, so progress is very slow.
next step is welding the new rear triangle. therefore the mounting at the frame had to be made, as well as the mounting for the bottom bracket and the dropouts.
material is 20x10x1.5 and 30x10x1.5 steel. dropouts is 10mm wide ST52.

thick tube in the lathe to fabricate two 10mm wide rings that will be central mount at the frame

both rings done. they fit tightly to the main 30mm axle.

all parts done (2 rings, and housing of the bottom bracket 63mm wide to fit a threadless bottom bracket, both sides have a 45° chamfer)

dropouts cut to size - a VERY tight fit. if you tighten the screw first then they are very hard to remove even with the screw removed

welding the frame gauge

dropouts in place - looking good

 

[docnjoj]

That is wonderful work izeman. This is the first time besides my Steintrike that I have heard of ST52 steel. Can you tell me a bit about its properties?
otherDoc

 

[izeman]

thank you other doc i love working on the bike, and not having the possibility to work a lot, i have a lot of time thinking about how to do it. so there's been a lot of brain work in the project.
ST52 is a stronger steel than ST37 which equals to "regular building steel". i don't know if these are international namings, but this is how steel was classified when i was at university. today ST52 is called S355 **** (or FE 510), it has a significantly hight tenacity than ST37 (S235) of a about 50%.
i didn't choose it on purpose, but i'm happy with it. it's easy to weld, and strong.

 

[vodk1c3]

Hey Izeman, have you done some testing on your battery pack? I have one puffer here from the 34 I received. :x

Great work!!

 

[izeman]

Hey Izeman, have you done some testing on your battery pack? I have one puffer here from the 34 I received. :x

Great work!!

i discharged every pack to 2.6v and charged to 3.6v. no puffed cell. only one or two where significally softer then the others. all of them gave between 18.500 and 19.900mAh during the 1c discharge. after sitting for some weeks now they are all 2.95v and balanced within 5mV.
internal resistance of the whole pack was measured by my ca-v3 at 0.1ohm for all 24 cells included all cable and connectors. but load was quite low, so this may change as higher loads are applied.
i hope they are performing well on the bike!!

 

[izeman]

update: yesterday was rear frame welding time a moment i was waiting for a long time.
unfortunately the bottom bracket tube was just 0.5mm too short, so i had to do it again. this is a threadless bottom bracket, and so the tube that it fits in has 2x 45° chamfers.

this is the bb inserted in the tube. it is a tight fit, and won't move.

this is a professional welder helping us

the first upper bar put in place

two rings 10mm strong to hold the axle of the main frame

second upper bar in place

the 2 front bars connecting the bottom bracket with the main frame. those have 2 bends to make space for the pedals and gears

welding

read damper support. two bended 3mm steel sheets

damper support done

all welding done

next steps will be cleaning the welds, and making the rear brake support as well as something to screw the controller to.
frame is 3.3kg. quite heavy, but lighter that i thought. @gerhard: quite a bit lighter than your whole street racer
comments welcome

 

[izeman]

today was wedding day
the new rear frame was fitted to the frame. what shall i say: all really nice. it looks a bit unusual, but you get used to it ...

rear derailleur is fitted as well, and next step will be the rear disk brake mount, and the controller mount.

 

[izeman]

this blackberry makes REALLY BAD pictures. it's time to take a real camera and make some good pictures

 

[izeman]

my problem now is, that cranks are way too long. standard 175mm cranks hit the floor when the suspension is all compressed.
(26"-21.6")/2 makes it 2.2" or 5.6cm lower then before. i know now what i forgot to change to the original frame design. i wanted to lift the bottom bracket
now i will need to finder shorter cranks, or shorten them myself. i was thinking to make them 140mm. this is still 2cm too long (compared to the original design), but better than nothing. the pedals will not hit the ground. but they may hit the ground in a turn.
what do you think? is 130mm too short?

 

[john7700]

I've been following this thread from the beginning as I have a Mantra that I am looking to convert. Exemplary job! I'm afraid I wont be able to mimic the advanced machining you have done here but it has given me some great ideas.

If you had made the bottom bracket higher, imagine how high the seat would be. It would look like a total clown bike. You are just going to have to go with the longest cranks you can get away with and be conscious of keeping the peddles at 6 and 9 when you dive in to a corner.

Looking forward to seeing the finished product and seeing some numbers!

 

[izeman]

I guess you are right. Moving the bottom bracket higher would also move the seat up. It already is quite high.
But I can't risk hitting the ground with a pedal on full speed when maybe jumping from the pavement onto the street. So I will make the pedals shorter.
Those Shimano ml750 from 1999 seem to be the last ones made of solid aluminum. As I don't plan to pedal a lot I think I can live with 130mm pedals.
Can't wait to install the battery and do a test run.

 

[izeman]

this is what it looks like now. it's almost done. rear frame is finished. ready to be tested. before i will let it be painted i will be testing everything. can gears be shifted nicely, is it easy to open the battery box (NO it's not , brake levers are in the way), are brake tubes long enough, etc etc ...
atm i'm fitting jst-xh connectors to the controller and parts. i could have done a test drive yesterday, but luckily weather was too bad (light snowfall), and i will be able to finish everything before testing it. trying this bike out was just tooooo tempting, and i was soooo close to riding it with cables hanging down from the frame and stuff

this is what it looks like yesterday evening:

 

[neptronix]

Dump 6000 watts into this motor and you'll see why you went through all of that effort very fast

By the way, you can buy cranks as short as 115mm. I use 145mm for my builds that have 20" wheels.

http://www.sinz-racing.com/product/SEC-19.html

 

[crossbreak]

Nice build, if you need sensorless 24fet 6kW+ controller for testing (very simple to hook on, since it's sensorless), just let me know, I can lent you one for a few weeks if you pay the shipping

 

[izeman]

thanks i guess i will have to switch to 18fet at least. i set the eb312 to 60a. even at temperatures around 0°C it seems i fried it. i made my first test run today, and it was really fast. 55km/h at a steep road with 15degree for about a minute pushing 4000w into the motor. i know that 2500w is the limit for continous power, but didn't "think" about it.
the bike suddendly stopped, and the CA went off. then came on again, flickering, and showing 62v pack voltage - which is not true. i will see what has happened.

 

[crossbreak]

my test controller can have adjustable current limit, upto 85amps. I would first add temp sensors into the motor, has saved many wires from burning already

 

[izeman]

Motor didn't get hot. I've a temp sensor installed. It was freezing outside, and I don't think that 1 min is enough to fry the motor. But it was enough to burn the controller, even if it was cold to the touch, something inside seems to have got burned. 2km with one controller - a quite expensive hobby

 

[izeman]

weird problem. i opened the controller. everything nice inside. no burnt parts or stuff.
but the shunt wire was loose. desoldered/fallen off? resoldered it and it's working again. now i will have to recalibrate the ca's shunt value, but still better than buying a new controller

i opened a new thread to discuss this issue: http://endless-sphere.com/forums/viewtopic.php?f=30&t=48534

 

[cmags]

Hi there, joined the forum to post this comment. Been watching your progress on this as your thread and pics come up when searching for info on the Klein Mantra. I have a '99 that I've been building the past few months for trail riding (normal human powered biking). This build is fascinating.

I wanted to suggest about your low bottom bracket that you may be able to find a longer rear shock to lift up the rear end a bit. Pinkbike.com has a large selection of used shocks (it's a forum like this but with a very extensive BuySell section) and 8.5" and 9.5" shocks are readily available. Changing the rear shock to a longer one will lift the bottom bracket and steepen the head tube angle so you'll have to balance the two to keep your front end handling right. I know this because I went the other way down to a 7.5" from the stock 7.875" and my head tube angle got too shallow/slack. Might be a quick and easy solution to your low BB.

Keep up the great work on this!