Tom's BEAST

[Whiplash]

MUCH better, I would suggest some aluminum side covers that either bolt on or velcro on to protect your legs from the belts and chains though, a 10,000RPM belt burn would REALLY HURT!

Like this:

download/file.php?id=71562&mode=view

[Thud]

food for thought:
http://www.tootechracing.com/Engine%20t ... ension.htm

[sn0wchyld]

food for thought:
http://www.tootechracing.com/Engine%20t ... ension.htm

damn thats a interesting link thud. I kinda had a feel for the 'chain pushes the wheel down' effect, but this really explains it well!

on a different note, this bike is looking sick. Defiantly want some sort of cover for that chain line for your legs, but otherwise looking good! Where's the new battery position?

[lostrack]

food for thought:
http://www.tootechracing.com/Engine%20t ... ension.htm

I ended up getting a girl to read this to me, like a bedtime story (*once upon a time*), drunk, on the bus home last night. Surreal.

Really interesting now I've had a proper read though. So, gassing it will give the bike a slacker feel, that should be wierd...

Better make sure the chain tensioner is bombproof

Totally explains the riding style of freestyle moto-x...check the below

[lostrack]

food for thought:
http://www.tootechracing.com/Engine%20t ... ension.htm

damn thats a interesting link thud. I kinda had a feel for the 'chain pushes the wheel down' effect, but this really explains it well!

on a different note, this bike is looking sick. Defiantly want some sort of cover for that chain line for your legs, but otherwise looking good! Where's the new battery position?

Thanks dude:)
It's the fox 40s I tell ya. First comment I get from anyone who sees the bike in the flesh is just how huge those forks are. Really, motorcross style.

Going from my second hand '02 Judy Races to these, it's just another world. So plush and now I understand how damping really helps. Will send them in for a service when I get time.

Battery position will be 6 batteries (2x2x2) below the downtube (cardboard placeholder). 7th in the front triangle of the frame, with controller.

After reading up on inductance, am trying to make battery cable lengths as small as possible.

T

[lostrack]

Hi all,

Update time - I've gone through 4 revisions to get the right chain tensioner.

[list=]
First, a single surly chain tensioner. Was loose, didn't take up slack
Second, fixed the slack - hard to the frame, but the position limited the swing of the arm and it couldn't take up enough slack
Third, total redesign, got mounting arms and sandwich plates, worked, but the alu was flexing too much (2mm treadplate)
Fourth - thick 1050 Alu, 3mm, super stiff.
[/list]

The biggest challenge was measuring the correct angle to drill at - if you mount everything onto the swingarm at right angles, the wheels aren't parallel with the chain and it pulls it off in a second.

The best heavy duty sprocket/jockey wheel I found was a cassette driver from a freehub body. Heavy duty bearings, and only 11 tooth. Works great!

Weekday workshop - I live in the city.

weekday workshop.JPG (74.56 KiB) Viewed 469 times

Version 3 - treadplate too flexible.

v3.JPG (78.06 KiB) Viewed 469 times

v3 outside shot.JPG (69.3 KiB) Viewed 465 times

V3 - outside shot. The new version has new plates.

Version 4 - happy!
(this is the view from the inside. A fixed roller and a chain tensioner)

v4.JPG (60.42 KiB) Viewed 469 times

The rolling resistance is minimal, I'm really happy about it. Plus the noise is barely audible under the ENO click.

I was worried it would be sticky and horrible. The SURLY chain tensioner takes up slack as you go through the travel.

Next - I'm affixing a chain guide to the motor.

T

[REdiculous]

Can you bolt the motor to the seat tube so it's as close to the rear wheel as possible? I think that's the first place I would've tried to put it since you shouldn't need idlers that way, just a good tensioner to keep the chain taught and off the frame. *shrug*

Looks like it should blast around once it's really going. Fun stuff.

[recumpence]

Can you bolt the motor to the seat tube so it's as close to the rear wheel as possible? I think that's the first place I would've tried to put it since you shouldn't need idlers that way, just a good tensioner to keep the chain taught and off the frame. *shrug*

Looks like it should blast around once it's really going. Fun stuff.

That would only move the unit back about an inch. Also, that would put a huge rotational stress on the seat tube. It is better where it is at.

I am curious to see how much suspension squat happens under accelleration.

It sure looks great!

Matt

[Doctorbass]

Man.. why making a Giant ebike so complicated

Put a good hub motor and that's it!

You'll still be able to fit 1.6kWh of lipo in the center of the frame and have the power you want without any noise!

yeah.... i'm kidding... ( please Recumpense font comment )

Do what you want...

I like to see all these complications people have... that i did not needed for my Giant

Doc

[lostrack]

Can you bolt the motor to the seat tube so it's as close to the rear wheel as possible? I think that's the first place I would've tried to put it since you shouldn't need idlers that way, just a good tensioner to keep the chain taught and off the frame. *shrug*

Looks like it should blast around once it's really going. Fun stuff.

That would only move the unit back about an inch. Also, that would put a huge rotational stress on the seat tube. It is better where it is at.

I am curious to see how much suspension squat happens under accelleration.

It sure looks great!

Matt

Thanks Matt:)

Suspension movement is 5 chain links, probably 6 bottomed out.

Doctorbass, making an unprecedented stop on the non-hub forum...welcome! Maybe a hub motor would be fun... but connecting 48 volts gives enough of a pop, I think I'd shit myself on 100v...

[lostrack]

Wow, long weekend.

Fabbed the aluminium battery box, did all the wiring, electronics, pre charge circuit, fuse, shunt & cycle analyst, mounted all onto the bike and I have a gaffa-tape running version.

Did my first run under power tonight - had some truly unimpressive videos (the chain came off twice...lol) that I won't bother posting.

It's fun though!!

I would describe it as mild EV grin, full grin reserved for daylight and full power.

NB. Going from default HV160 settings to the recommended settings, frock me...this thing flies! (the throttle response is brutal)

cheers

[minuteman2k]

Lostrack

Check this out and you might throw it all out and start again

mini moto 6-1 oil filled gearbox, tandom freewheel with pit bike sprocket/chain, 8 speed grip shift, Castle HV140, Emax 6055

Listen Carefully you can here me Shifting the 8 Speed sequential Gears



2.2kw @ 24volt
6+ Kw @ 48 Volt

45MPH +++ if you can control the current,
all i needed was an RC cycle analyst

[lostrack]

Latest updates - have been busy.

Re-did the chain tensioning system again, with 2mm alu plate. This is going to be heavy, but won't flex.

Also, uprated all the moving parts to heavy duty BMX casette drivers, and had an ironmonger LEGEND grind them down on the lathe, they came out beautifully.

Hard wearing, ball bearing'd jockey wheels, boom.

bike - 2 new jockey wheels.jpg (94.39 KiB) Viewed 617 times

Then, got an 80Tooth chainring. This is clownstyle big. I'm pretty sure all you can do is flip over on full power, but there you go...£100 lighter. Live and learn.

bike - comically big chainring.jpg (166.3 KiB) Viewed 617 times

...and the bike. Gaffa tape build. It works though!!

bike - status jan 26.jpg (144.29 KiB) Viewed 617 times

I'm having trouble with the motor literally pulling the chain off the sprocket. It drives, and I get up to top speed...but it's skippy the chain kangaroo at the moment.

New spring (custom!) for tensioner arriving tomorrow. If it works, I'll post videos this weekend.

cheers

[Whiplash]

Its skipping the small sprocket or the big one?? Maybe morecwrap on the small one could help?

[lostrack]

Its skipping the small sprocket or the big one?? Maybe morecwrap on the small one could help?

I'm not sure, it's hard to tell - but on the brand new 80T there are clear chain slipping marks so I'd guess a mixture of both. The teeth on the ENO freewheel are quite a bit more protruded than the rear chainring.

More wrap on the ENO would involve another tensioner, I already have 2 guides and a tensioner, it's all starting to create a headache...hence my thread on driving through the casette.

I'll re-join the broken chain and see if the new spring for the tensioner helps. If not I've had a few ideas I can try this weekend.



I need to securely mount the batteries to the frame now...any inspiration??

[sn0wchyld]

PVC square pipe, PVC cement + primer, a heat gun, an angle grinder/saw + tinsnips and some Velcro double sided tape. The glue is as strong as the pvc itself, you can easily shape the pvc into curves to fit over your frame, and you can often find it in dimensions to fit your batts really well. Tinsnips work great for detailed cuts. And the velcro tape is a great temporarily permanent alternative to ductape, very strong too. I'd be making a U shape peice to fit up under your lower downtube, glue two long boxes for batteries to either side and use some long strips of Velcro to hold it on. Some stick on foam for padding would help too.

[lostrack]

New battery box, solid.

Beast Jan29.jpg (185.44 KiB) Viewed 525 times

Beast Jan29-3.jpg (189.29 KiB) Viewed 525 times

Shagged a chain again. Doubled up with two surly chain tensioners in parallel, still not enough tension.

The chain is now so tight that its adding drag freewheeling. Will try and ramp it up some more...but damn. How tight do I need to go?

[Sharkboat]

Great build, i'm jealous. You used a few similar components to what Doctor Bass used on his crystalyte Giant DH Comp bike. How do your efficiency and range compare to his? I believe he is using much more lipo than you, but similar variety.
http://www.evalbum.com/3406

[lostrack]

Thanks Sharkboat. It's getting there:)

Range is about 30 metres, or 10 seconds use, whichever causes the chain to snap first.

[recumpence]

I have never skipped a chain. It sounds like it may be from the suspension movement causing slackening, tightening under power.

Wierd.......

Matt

[waynebergman]

Nice bike Tom.

Just an idea here and I am sure you have thought about this already but its worth a shot. I know in the past if I have mixed an matched old chain rings with new chain or the other way around things don't mesh together as they should. Any chance you are using an old stretched chain with new sprockets?

One more thought with the single pivot design of course is there will be that tugging on the chain under compression that might just be normally a slight bit of feed back into the pedals on a normal pedal bike with this single pivot design, but with the high torque of your motor and sprockets combined with rider weight might just be too much. Just guessing here?

[rodgah]

dont give up man, it is something simple. I have had some pretty crazy chain angles on the ENO (like max 5t engaged) and never skipped a tooth, thats with 2 x 3220s

my first setup was similar to yours i think....chain tightened as the suspension compressed by about 5 links length, never had a single issue with the chain skipping, apart from if you jumped on the cranks with so few teeth in contact.

IMG_0018.jpg

(168.91 KiB) Downloaded 3 times

what brand/size chain are you using?

Keep at it

[Grinhill]

Great build Tom.

I've gotta ask the silly question, is it one of those chainrings with asymetrical teeth, like a ramp on one side of each tooth? If that was flipped the wrong way, the chain would tend to ride up the ramps.

[Alan B]

Is that large chainring flexing? Maybe use the videocam to capture the event??

[lostrack]

Thanks for all the support everyone.

I took it for another spin this morning and it turns out that the tensioner is at maximum travel with rider weight on it, so it naturally comes loose. When you hop off to see....it's tense again!

Removed some chain links, will try again tonight/tomorrow.

It's like this bike will refuse to exist unless it has caused enough headaches, drawn blood, broken tools.... I'm sure we are just building up a mutual understanding...