Spun front axle and flew over the bars @ 25mph

methods

methods

1 GW
Joined
Aug 8, 2008
Messages
5,555
Location
Santa Cruz CA
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I put a Nine Continents kit (front hub) on a 20" boys Walmart chopper bike.
By my calculations the drops were fine for the *forward* acceleration torque
I failed to calculate in the *regenerative* torque....

I had ridden all day on a 12S 10Ah Lipo pack and the voltage was down around 40V
I was going down hill at 25mph at full throttle
I "snapped" the throttle off which instantly threw the motor into generation
This was more than the drops could handle, the axle spun out, then the front wheel flew off the bike

My front forks hit and catapulted me through the air and I slid 15' on my side into the intersection.
It was at night and I was wearing all black
I crab walked the bike, wheel, and myself off to the curb and then stood up to wave off all the cars that had stopped to help. Lucky for me I was wearing gear: Full face helmet, leather gloves, and an armored motorcycle jacket.

I slid far enough and hit hard enough to gash the helmet, rip the arm of the jacket, and give myself a sweet raspberry knee. A USB thumb drive that was in my left hip pocket embedded itself into my thigh. Other than that and a very sore right shoulder & left hand I walked away nearly unscathed.

Allow me to call a moment of silence for anyone who is foolhardy enough to ride without at least gloves. Had I not been wearing gloves my palms would be hamburger.

And er. . . . Dont be a jackass like me. Use a torque are whether you need it or not.

That is the second hub motor I have spun out and now I think I get it. . . . USE TORQUE ARMS. :roll:

But hey, I don't want to die without any scars so two thumbs up for a near life experience. :idea:

-methods
 
Maybe keep hub motors on rear axles?!?!?!?!?!?!? They seem to do less damage when they spin and fall off. Best of luck healing quickly!
otherDoc
 
docnjoj said:
Maybe keep hub motors on rear axles?!?!?!?!?!?!? ...
Click to expand...

Could not agree more.
My 100V X5 monster is on the rear and I would never dream of putting it on the front

I made the mistake of thinking that a "little old 800W nine continents kit" was a toy that I did not have to take seriously. It surely is not a toy and even a small hub motor can pack a punch (ha ha).

How about: "hub motors on the front *must* have a torque arm?". As I suspect that many like FWD and that statement will probably be easier to swallow.

-methods
 
Phew.. glad to read that you are ok !!!

I fully agree, i wear my full face Giro and gloves at all times.

Hub motors on front axles is a touchy subject, i have my eZee on a front dual crown RST suspension fork and i don't worry enough about it.. :lol:

Was it possible to determine if the axle nuts came loose or if the dropouts broke ? was it a good fit with good clamping force ? or was it dodgy on a cupped dropout ?

Regen means the problem happened at speed, vs during acceleration that would happen at low speed, either way it's bad news when the motor and bike part ways.. i've witnessed it first hand and it SUCKED.......( Stationary test, wheel of the ground, hit the brakes on a 700C wheel while under power with a 4011 and 48v,,,, BRrowwmpttt. WHOA.. )
 
We.Want.Pictures. :twisted: :twisted: :twisted:
 
Yeooouch! Good thing you landed good and didn't break stuff like I did. Leathers and hemets, good! Makes you wonder if regen is worth having at all! Or was it just the normal cogging force that did it? And more proof that current technology for attaching motors to bikes is not mature. We need bettter dropouts than any bike is made with, and maybe thicker axles with longer flats, deeper nuts to keep em tight, and all sorts of stuff once we get over 15 mph.
 
Ypedal said:
... Was it possible to determine if the axle nuts came loose or if the dropouts broke ? was it a good fit with good clamping force ? or was it dodgy on a cupped dropout ?
Click to expand...

I ground them down perfectly flat (removed the catches), it was a perfect fit, and they were tight as hell.
I was going full speed and the regen just popped it. I suspect the busted-ass walmart quality mild steel drops. They just rounded out like butter then spat the axle out.
I will weld them back up to 1/2" thick and it will be golden.

-methds
 
pwbset said:
methods said:
I made the mistake of thinking that a "little old 800W nine continents kit" was a toy that I did not have to take seriously.
Click to expand...

http://ebikes.ca/store/store_nc.php

Ebikes.ca said:
Due to the higher torque output and the lack of an extended keyway on the axle, these hub motors are more prone to axle spinout than the Crystalyte 400 series.
Click to expand...

:mrgreen:

Glad you are okay.
Click to expand...


If you read the rest they say that they are going to supply torque arms later but that it is fine now if you torque it up well with no torque arm.
Regardless. . . Front hubs need torque arms.

-methods

EDIT: Lets be clear that this was MY MISTAKE and had nothing to do with the ebikes.ca kit
 

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Sounds almost like my accident, now I have a saying "loose nuts cause sore butts." :cry: On my third set of forks, and hub motor posted for sale. These front hubs are a menace and should be outlawed (although I still ride mine). Glad to hear you survived (who would feed all those monkeys?).
 
Gets tempting to weld the nut to the dropouts and the axle to the nut, don't it? Or maybe dropouts made out of 10 mm wrenches?
 
Two things:
* This is one of the original design considerations for recumbents. Flying over the handlebars is a common characteristic in serious bike accidents. If there is a similar fork failure on a recumbent, you pretty much end up on your ass and have your hands free to deflect or go feet first. On upright bikes, its a potential face plant with your hands the last to leave the bars.
* It spells out the basic critical nature of forks. Its one of the few mechanical failures on a bike that is potentially catastrophic.
Except for hub motors, the vast majority of fork failures are from modified or home built forks. Very serious stuff.
That said, forks can be overbuilt and easily handle the stress of a conventional hub motor - under most conditions.
Glad you're OK.
Rob
 
Did the crash damage your lights?
 
TylerDurden said:
We.Want.Pictures. :twisted: :twisted: :twisted:
Click to expand...

Yes we do damn it!!!!1oneoneone We urged you on in the challenge of climbing stairs in hope of getting some face plant footage :lol: all we needed to do was wait for you to install a front hub motor but you missed the shot... DOH! :p

Seriously though glad your ok Methods... 8)

Kim
 
JinbaIttai said:
Did the crash damage your lights?
Click to expand...

Excellent question!

I had my prized 900 lumen lithium flashlight on there. I was sure it was going to be trashed but it was fine!
Of course the LED rear light and the LED tire flys were fine as well.

This flashlight is nuts.
http://www.lighthound.com/Ultrafire-WF-1000L-900-Lumen-SSC-P7-LED-Rechargeable-Flashlight--2-x-18650-or-18500-batteries_p_6-2624.html
There are tons of reviews and tests.
I got the 2400mah internally protected batteries and an el-cheapo charger that sucks. The internal protection and the charger are total garbage but the flashlight runs on constant current so it does not matter.

So what makes you ask?

-methods
 
AussieJester said:
TylerDurden said:
We.Want.Pictures. :twisted: :twisted: :twisted:
Click to expand...

Yes we do damn it!!!!1oneoneone We urged you on in the challenge of climbing stairs in hope of getting some face plant footage :lol: all we needed to do was wait for you to install a front hub motor but you missed the shot... DOH! :p

Seriously though glad your ok Methods... 8)

Kim
Click to expand...


In the end I feel a lot more bold now. I always thought the ultimate crash would be losing the front wheel . . . Now what have I got to be scared of? Sliding out on a fast turn would be cake compared to the dive I took. I want to make a video like the one on eMTN where the guy is in the parking lot scraping peddles hard with huge slicks on the bike. Check this video out.

Right below: "Bomber - Test 1"
http://e-mtb.com.au/library.html

-methods
 
Hi Methods,

sorry to hear about your spill :(
we've been here a hundred times and all we cansay is TORQUE ARMS!!!!
even though i have rear wheel drive and im moving away from hub to chain drive i am still insisting on torque arms for the new build, my wheel builder didn't see the ned for them as i don't have the torque at the axel now but i assured him that it wasn't for the torque, but to make it impossible for the wheel to come out of the drops - in my opinion you should fabricate torque arms not only to reduce twisting drops but to secure the wheel into the drops encasing the axel in something solid.
you know it makes sense.

Cheers,

D
 
hey, way to cheat megadeth.
just don't get too bold.

Considering there are a number of motorcycle types around here it's strange, but something I've never seen mentioned on the Sphere (or any other of the ebike forums for that matter) is the subject of wire-tying the axle.
Would that be of any worth, at least keep the nuts from backing off?

I currently don't do it since I have a beefy torque-arm & can't go past 20 mph anyways, but will definitely add it when I mod the controller.
At a min I figure it's gotta be chicken soup.
 
Glad to hear you survived without serious injury.

Now ya go me thinking about buying a jacket and some other protection in addition to my motoX gloves and Bell mira skate board helmet. (more coverage than standard bike helmet)

Anyone have any suggestions about where to find some comfortable jacket or jersey with built in body armor?
 
Well, that sucks. But I think a large problem is that bikes aren't really designed for the bidirectional torque of a hub motor as braking is largely in one direction(And that's about the only major force I can imagine normal bicycles have to worry about, when talking about the "forward"/"backwards" forces on the front wheel and fork.). I'm glad this didn't happen during the day where skidding into an intersection can mean almost certain death. I've seen far too many stories about -cyclists(motor and bi) being thrown off their bike and then literally being ran over by traffic.
 
Microbatman said:
Anyone have any suggestions about where to find some comfortable jacket or jersey with built in body armor?
Click to expand...

There are plenty of motorcycle jackets that are based on a light weight mesh with plates inside, then a removable inner "warm" liner.
My best advice is that you need to try a few on. Every motorcycle jacket is different and you will find that some are terrible. . . The pads move around, it is hard to get on, the liner is clunky, the pads dont sit in the right spots for your body type, etc. I tried on 20 before I found the one that just slid on. All the pads in mine are removable and the inner liner is WARM. Without the liner (and with all the vents open) it is cool enough for 100 degrees. I bought different pads for different activities. For instance I have a back pad that is just thin memory foam for day to day but I have a replacement that could double as a bullet proof shield (picture landing on your back on a large sharp rock).

I dont know if my Project Mayhem bike will ever see true downhill but I will be ready if it does.

-methods
 
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