Giant DH Team, Cromotor, 18fet Lyen, 111v Lipo

This kills me to look at the axle... *cringe* rethinking 9kw. I've been running It at 145A phase 90A battery (~5kW) in a ginormously stupid 28.8" wheel and I'm surprised this hasn't happened. What power level were you at again? Can we establish a safe power limit in a16-20" wheel?

Based on some calculations involving slope angle and full throttle torque , wheel size, etc., we may be able to get a ballpark torque rating
 
don't blame yourself so quick. most of us have filed our axles to upgrade the phase wires. take more pics. big moose (edit: found it->)identified the failure of another axle. i can't remember which now. but a 53xx xlyte. neils? anyway, if there's something inherently faulty with the axle, we all should know about it. of course it may have been your fault, but sometimes the true cause is elusive.

i wonder if these axles were properly hardened, cause they're not as strong as 9C's. i have no idea what the manufacture is like, but i noticed in the old Raleigh video how they hardened the bottom brackets..
 
hillzofvalp said:
This kills me to look at the axle... *cringe* rethinking 9kw. I've been running It at 145A phase 90A battery (~5kW) in a ginormously stupid 28.8" wheel and I'm surprised this hasn't happened. What power level were you at again? Can we establish a safe power limit in a16-20" wheel?

Based on some calculations involving slope angle and full throttle torque , wheel size, etc., we may be able to get a ballpark torque rating
Click to expand...

Gimme sometime and we will find out if the axle (unmodded) snaps when launching with over 12kw of power
 
That's the same axle that's on the original motors, like the one in my bicycle now. The new ones appear to be different material but I can't say for sure. I know the original stuff is pretty hard since I managed to strip the threads out of a nut and didn't hurt the threads at all.

Any idea how much material you think you removed? It looks like it broke at the thinnest area. I think the new axles are thicker in the area where yours broke but I'd have to take my wheel off and measure or find a picture to be sure.

The other question I have is how was your torque arm setup? A torque arm can could act as a shear if it's not on flat or frequent movement occurs. Is the break right at the torque arm edge or in a different location. I want to make sure I don't have to worry about mine at all when I pump lots of power into it, but being that I run a 20" OD tire I probably experience less stress since there is absolutely no way I can go WOT @ a 100A battery limit into it from a dead stop and expect to stay on it even if I'm leaned all the way over the handle bars, just not going to happen, maybe with my 12" longer swing arm I might be able to.
 
I was running a 36fet Greentime controller(http://endless-sphere.com/forums/viewtopic.php?f=30&t=33636&hilit=greentime). It was configured to run at 100a battery. But it wasn't configurable past that. It's freaking HUGE! But I mounted it along my top tube between my legs.

Unfortunately my CA is not working (blew a cap), so I'm not sure how much power I was actually pulling. But I imagine it was above 5kw...

I was at a dead stop and hammered the throttle 100% on the "lowest" 3-way setting on a very slight uphill. Don't get me wrong this.. even on the "low" setting, the bike still wanted to take off like a bat out of hell. I have to move all my body weight over the front wheel to prevent a wheelie... but i kept it down, until the axle snapped :(

Thanks for those words GC, I'll just chalk this one as learning experience. I understand at these power levels... stuff happens... especially since this is my first bike.

I only took off a little bit in the wire channel... somewhere like 1mm? I've tried to illustrate where I've done that in the red in the image above.

I'm using the Kiwi dropouts... everything felt tight, but I'm not a dropout expert. The axle snapped on the edge of the dropout.

I'll inspect the other side of the axle and see if there is anything wrong with it as well.

But looking how thick the wire channel is and it just feels very small.

I think i'm going to go with a smaller wheel diameter. I'm getting tired of blowing everything up :p
 
Hi,

Fortunately you don't get hurt :)
You can see my setup on my sign, I'm going to switch the crystalyte for a cromotor.
You should go with 17-18" motorcycle rim. The smaller diameter will put less stress on the axle and you could run less amp as said before.
I saw your video, your setup was freaking awesome 8)
 
What exact size are the batteries?

I planning a very similar build, also with a Giant DH Team frame, and 24S 3P of these batteries, http://www.hobbyking.com/hobbyking/store/__24861__Zippy_K_Flightmax_5000mah_4S1P_20C_Lipoly_Battery.html

As it looks on your first pictures, I should be able to fit 12 of thoose batteries inside the frame.

Doesnt it feel wierd with 130-150mm width between your legs when pedaling? I have only 120mm now, but sometimes hit the batteris with my knees.
 
I've been dealing with a financial and personal $@#! storm over the last two months. I've gotten things back under control.

I have the stater and axle just sitting on my shelf staring at me. I should be able to get it sent out to you by the weekend if you still want it. I'm sorry for the delay, there is no rush to get it back.

On the plus side... I've been successful in riding my bike through all this crazy Canadian winter!
 
@ binlagin

was the other side af the axle also broken or not?
what is the cross section of the upraded phase wires?

On the cable side there is the weakest point of cromotor axle. Lots of different forces do appeal there. Motor torque force, the force which push your bike forward and the tensile stress from tightening the axle screw. This tensile stress from the big screw you could nearly totally avoid if you only tight until it doesnt wobble in your torquearm and not more. If you do so, you need torquearms with screws to clamp the axle. As far as i could see your torquearms don't have the option to clamp the axle and this is bullshit.. With that high power, axle clamping is really necessary and only with this you can avoid tighten the big axle screws to much. Without tightening force there will be more room for torque and acceleration forces.
 
You must log in or register to reply here.

Similar threads

Metallover
ML DH Comp Cromotor Max-e Build
2
Replies
30
Views
10,860
Metallover
Metallover
C
4motus / cromotor DH bike build
6 7 8 9 10
Replies
244
Views
29,392
BoomerChomsi
B
Scott
Scott's Giant DH Team Build 66 mph!
2 3 4 5
Replies
100
Views
24,060
Scott
Scott
Obiwan007
New Giant DH Team/Cromotor build thread
2 3 4
Replies
82
Views
12,916
Metallover
Metallover
tricky43
Tricky43's Giant DH Team Lyen 4115 x5306
Replies
14
Views
6,517
whereswally606
W
Back
Top