Search found 159 matches

by mat h physics
Oct 27 2018 2:22pm
Forum: E-Bike General Discussion
Topic: Input needed... 30mph cruise and 40-45mph top speed ebike
Replies: 20
Views: 755

Re: Input needed... 30mph cruise and 40-45mph top speed ebike

Let's start where the rubber meets the road, tire pressure is key to an efficient setup: http://www.dorkypantsr.us/bike-tire-pressure-calculator.html Allow me to translate why 'fat tires' are not practical for such a build. It's been tried by another member, and I can't find the post, but 'fat tires...
by mat h physics
Aug 30 2018 10:59am
Forum: E-Bike Technical
Topic: 60v hub motor, 52v28ah battery, 48v45amp controller
Replies: 7
Views: 310

Re: 60v hub motor, 52v28ah battery, 48v45amp controller

There are better ppl to respond than me, though you've overlooked some basics. The only thing restricting the motor voltage, is it's insulation. I doubt you want to go through the trouble of using a Mega-ohm meter, but it uses much higher voltage. Current will be restricted by heat capacitance and d...
by mat h physics
Aug 29 2018 6:50pm
Forum: E-Bike General Discussion
Topic: Newb Needs Help with Build Questions
Replies: 33
Views: 772

Re: Newb Needs Help with Build Questions

Proper tire pressure will be the easiest improvement to handling/braking. Don't skimp on the tires, Flat Protection Strips(fps) are worth the convenience, even if it doubles tire cost. Added weight will require higher pressures, confirm pressure rating before purchase. http://www.dorkypantsr.us/bike...
by mat h physics
Jul 13 2018 12:04pm
Forum: Electric Aircraft
Topic: Zunum Aero, hybrid aircraft
Replies: 9
Views: 742

Re: Zunum Aero, hybrid aircraft

I'm of the impression a rotory engine would be used, due to efficiency of designs. Primary drawbacks for Wankel designs, high exhaust temps and narrow band of efficient RPM. Heat transfer at altitude shouldn't be a problem, and the hybrid system would easily be 'tuned' for max efficiency RPM. The on...
by mat h physics
Dec 26 2017 2:13pm
Forum: E-Bike General Discussion
Topic: Convert 29er wheel to 26"
Replies: 10
Views: 694

Re: Convert 29er wheel to 26"

amberwolf, you're certainly one of the best on the board. I think an agreement can be seen in the shift of eff at high RPM. Thank you for posting data to back your position.
Happy New Year
by mat h physics
Dec 24 2017 10:21pm
Forum: E-Bike General Discussion
Topic: Convert 29er wheel to 26"
Replies: 10
Views: 694

Re: Convert 29er wheel to 26"

Keep in mind that the top speed will drop proportionally to the wheel size difference. However, the torque will increase proportionally. ;) While things in 'the real world' may seem simpler, motor theory says output will be the same. IE top speed should not suffer, the 'added torque' drops off at a...
by mat h physics
Jun 28 2016 7:22pm
Forum: E-Bike Technical
Topic: carbon fiber and brass torque arm?
Replies: 19
Views: 1148

Re: carbon fiber and brass torque arm?

Brass is a creep metal, though beryllium copper is used for springs. Warning beryllium copper dust, ie machining, is toxic to the human body. Not something you just take a hacksaw to.
by mat h physics
Jun 28 2016 7:16pm
Forum: E-Vehicles General Discussion
Topic: TesLorean
Replies: 1
Views: 289

TesLorean

No recent updates, but hope the guy succeeds.
http://www.teslorean.com/
by mat h physics
Feb 03 2016 6:50pm
Forum: E-Bike Technical
Topic: $14.99 72v Sunwin Controller
Replies: 456
Views: 39164

Re: $14.99 72v Sunwin Controller

Tagged to follow.
by mat h physics
Jul 15 2015 9:55am
Forum: E-Bike General Discussion
Topic: Down under ID?
Replies: 6
Views: 449

Down under ID?

How close are you guys to this statute passed?
http://www.smh.com.au/comment/photo-id- ... 715-gicgkd
by mat h physics
May 18 2015 1:30pm
Forum: E-Bike General Discussion
Topic: A different spin on magnets
Replies: 0
Views: 217

A different spin on magnets

Recently found this video: https://youtu.be/VWMu0cndKl4

Have started the e-book, looking forward to learning new things. :D
by mat h physics
May 10 2015 4:27pm
Forum: E-Bike General Discussion
Topic: Anyone DIY a R side brake caliper mount on susp fork
Replies: 24
Views: 1013

Re: Anyone DIY a R side brake caliper mount on susp fork

I need to get a braking distance from over 100mph reasonably short. Right off the bat, my though was you need to go full blown moto, bicycle brakes won't be enough. Glad to see you found an alt, though keep in mind drum brakes have an inherent flaw of locking up easy. And while you may not even be ...
by mat h physics
Apr 18 2015 8:42pm
Forum: E-Bike General Discussion
Topic: Independent power sources?
Replies: 3
Views: 506

Re: Independent power sources?

Got a PM on this, his concern was C rating SC vs bat. As for the videos, they are demos of how to fabricate supercaps via basic chemistry and layering techniques. His numbers appear to be close to what commercial SC produce. Yet by fabricating in shop, the option to stuff in frame tubes or shape a f...
by mat h physics
Apr 18 2015 8:51am
Forum: E-Bike General Discussion
Topic: Independent power sources?
Replies: 3
Views: 506

Independent power sources?

Is there a, currently, off the shelf controller which uses dual power sources? Here is purpose: While some claim "homemade battery pack", here is how supercaps can be fabricated: [youtube]https://youtu.be/iD2rVGjG2HQ[/youtube] [youtube]https://youtu.be/nRM0x-AqrTk[/youtube] Ladder logic, antiquated?...
by mat h physics
Apr 07 2015 6:43pm
Forum: E-Bike General Discussion
Topic: Got tagged this morning
Replies: 21
Views: 1548

Re: Got tagged this morning

Did you get a picture?
Was it in ink or paint?
Stay safe.
by mat h physics
Mar 26 2015 8:35pm
Forum: E-Bike Build Threads / Photos & Video
Topic: Ultracap Bike
Replies: 105
Views: 34903

Re: Ultracap Bike

Re Bump! :shock:
by mat h physics
Dec 03 2014 9:34am
Forum: E-Bike General Discussion
Topic: 24 volt 36 volt AND 48 volt
Replies: 23
Views: 3830

Re: 24 volt 36 volt AND 48 volt

Really like that setup Ykick, contemplating DD or GH for a while. Leaning GH, due to high weight and only really wanting it for steep hills. As for BMS, is this ES common knowledge? I posted this when reading a book on large BMS, http://endless-sphere.com/forums/viewtopic.php?f=14&t=55341&sid=9119cb...
by mat h physics
Nov 29 2014 10:24am
Forum: E-Bike General Discussion
Topic: 24 volt 36 volt AND 48 volt
Replies: 23
Views: 3830

Re: 24 volt 36 volt AND 48 volt

The purpose of using AC power in transmission is to ramp voltage up for lower power losses. More power is lost due to amps than volts. This was a real problem for Edison when he started his power company, as the furthest customers were getting dramatic power loss. Think it has something to do w/ cre...
by mat h physics
Nov 14 2014 5:30pm
Forum: E-Bike General Discussion
Topic: Is a bolt together frame a bad idea?
Replies: 17
Views: 1544

Re: Is a bolt together frame a bad idea?

The real problem comes from a non precision fit. The bolts will slam the holes overtime, making them bigger and eventually failing. Such designs rely on friction joints to prevent movement. You don't have to weld, consider brazing (steel). Learning: Wisdom- 1st hand knowledge, the wise old man. Inte...
by mat h physics
Nov 11 2014 11:19am
Forum: E-Bike General Discussion
Topic: My crack at building the fastest hotrod 9C on the planet...
Replies: 33
Views: 2006

Re: My crack at building the fastest hotrod 9C on the planet

Enemy nr 1: Heat: - "normal" heat buildup - "excessive" heat buildup due to copper mass limitations Enemy nr 2: Constructional weakness: - Danger of warping axle and center stator "frame" - Danger of warping side covers - Frying hall sensors - Burning out copper wire after exceeding its assumed pow...
by mat h physics
Oct 29 2014 9:31pm
Forum: E-Bike Reviews & Testing
Topic: Crystalyte X5304 48V20A Kit with NiXX battery (used)
Replies: 22
Views: 7364

Re: Crystalyte X5304 48V20A Kit with NiXX battery (used)

Pardon me for throwing a monkey wrench, amberwolf, it appears only having two points to secure a plate will create a "hing" effect on such a simple arrangement. The plate system may not handle thrust force, such as turning. Three points define a plane, you have parallel lines that will have difficul...
by mat h physics
Oct 27 2014 8:07pm
Forum: E-Bike General Discussion
Topic: Aluminium Torque Arm ? Have you made your own ?
Replies: 20
Views: 1941

Re: Aluminium Torque Arm ? Have you made your own ?

The reason for using a file to determine hardness, is to find the metals allotropic stage: http://en.wikipedia.org/wiki/Allotropy Iron and Titanium have this property, it's hardness will give an indication of how well it can stand up to the high torque forces. Beryllium copper would have to be shape...
by mat h physics
Oct 26 2014 10:14pm
Forum: E-Bike General Discussion
Topic: Aluminium Torque Arm ? Have you made your own ?
Replies: 20
Views: 1941

Re: Aluminium Torque Arm ? Have you made your own ?

Aluminum is a creep metal, it will not hold up to the high stresses of such a small axle. Steel is going to be an only option unless you have a source of titanium or beryllium copper. Beryllium copper dust is very dangerous to human heath. It's going to cost more in the long run to experiment w/ alu...
by mat h physics
Sep 03 2014 5:59pm
Forum: E-Bike General Discussion
Topic: Riding position
Replies: 3
Views: 435

Re: Riding position

Well for some reason I can't get the utube display to work, but this lady is on a higher level: http://youtu.be/rWYemEeLTTE
And who knew, "you ride like a couple of girls" could be taken as a complement: http://youtu.be/fhmIDBiI3os