Catastrophic failure

MechMike219

Active Member
Local time
9:15 AM
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Dec 16, 2022
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126
well... as much as i hate to say it, bike broke again.. snapped the rear axle at around 50 ish and thats pretty much when everything decided to rip itself apart. im guessing once the axle broke the wheel shifted and hit the frame, so began the skidding and violent separation of sprocket from hub onto the chain jamming into the case and side cover. burnt a hole in my back tire from the 60 feet of asphalt it skidded a crossed. im also led to believe that when the chain jammed up, it bent my clutch shaft and im 110% positive it broke a bearing. ill load the pics of the destruction in a little bit. oh, it also bent the motor chain side frame dropout as well as cracking the frame just behind the bottom bracket where it splits off. ive already straightened the bent section and the crack will be getting addressed day after tomorrow. back to riding a spoke wheel again. sketchy considering its got junk caged ball bearings and a macguyvered sprocket/rotor combo rag jointed to a wheel i found in the trash.. it rolls tho.. so now im on the hunt for some badass and nearly bulletproof wheels that A) can withstand high speed B) durable for long rides C) both A and B. Im not sure if i wanna go back with mags again or if i wanna go spoke wheels. not opposed to either one tbh.. any thoughts or suggestions? they dont necessarily have to be complete wheels, if i can get ahold of hubs, i can lace them to whatever i want myself. an acquired skill that came along with being a hardcore dirtjumper and street rider, quite useless the last 15 years or so... till now.. lol

on a further note... im fine. i stayed uprite. that was the bmx'r in me and alot of luck. it definately couldve went down way worse than a couple broken bolts and a flatspotted tire. thats a constant reminder of Murphys law... Anything that can go wrong, will
 
That plug tho..
 

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I would buy either Worksman wheels or Gemini wheels. Grubee has a super good rear wheel, that's priced right & built solid. The grubee wheel uses 4sealed wheel bearings in it.
 
Looks like a cast metal rim, or is it plastic? Seems we've had a couple of axles break recently. Reminds us to not cheap out on quality when it comes to the important parts. OP do you think that casting on the side of the hub broke due to the axle breaking or vice versa?
 
Looks like a cast metal rim, or is it plastic? Seems we've had a couple of axles break recently. Reminds us to not cheap out on quality when it comes to the important parts. OP do you think that casting on the side of the hub broke due to the axle breaking or vice versa?
cast metal, its the 5 star mag from bikeberry. I got 2 years and a few thousand miles on em. it was bound to happen. im leaning more towards the axle. i had replace the bearings a couple weeks ago but.. not the axle, "looked fine" apparently not. also the way it broke. the 3 bolts that ripped out of the hub didnt break, 2 did, and one lonely survivor stayed its place.. clean break on the axle btw.. funny part is when it locked up, my first instinct was pull the clutch and rear brake lever.. mmhhmm.. neither one helped.. wheel locked up sliding, brake did nothing, as for the clutch, motor shut off when the chain locked up. ill admit too, i was riding the hell out of it the previous 4 or 5 miles. and that motor is making some decent power now since the pipe..
 
Why is it we see soo many mag wheel axle failures? Do you think since it's a mag wheel it puts more stress on the axle, because the wheel itself dont flex like a spoke wheel does. It seems we see 2-5 mag wheel axle failures a year. Or do you think its cause lack of maintenance & the wheel bearings eat thru the axle from lack of lubrication/adjustment.
 
Most important thing out of all this is the only thing hurt on the rider is maybe a little pride. The Chinese metals are all so unbelievably weak. Sometimes I wonder if they throw a little sand in the metal pot to stretch out the actual metal. The metals really cannot be trusted at high speeds on the bicycles.
I would bet all the mag axle failures are happening in the same place along the shaft. Something is creating an environment at that spot causing the shaft to snap. A similar happening...I've seen big Johnson and Evinrude boat engines...V6's... snap 3/4" or 19mm stainless steel shafts all in the same spot many times. On a bike axle you have the rider's life at stake.
Cannonball has suggested several times for me to ditch the crappy wheels I ride on and get a set of Gemini's. My avatar is a reference to all this same thing. Riding at high speeds on cheep a$$ wheels is a recipe for disaster. Some of the mags sold…or at the least those axles..may be good for much lower speeds but once you get going above 45 - 50 mph it's a good idea to have the correct wheels to support this.
Thankfully MechMike you're ok and ready to rebuild. That's good news.
 
Most important thing out of all this is the only thing hurt on the rider is maybe a little pride. The Chinese metals are all so unbelievably weak. Sometimes I wonder if they throw a little sand in the metal pot to stretch out the actual metal. The metals really cannot be trusted at high speeds on the bicycles.
I would bet all the mag axle failures are happening in the same place along the shaft. Something is creating an environment at that spot causing the shaft to snap. A similar happening...I've seen big Johnson and Evinrude boat engines...V6's... snap 3/4" or 19mm stainless steel shafts all in the same spot many times. On a bike axle you have the rider's life at stake.
Something less thought of that can also cause an axle/bolt/stud to snap is loose tolerances on the spacers and/or bearings when there is stacking and high stress perpendicular to the shaft. I used to see this a lot when guys would use random washers to space a rear shock they adapted from another motorcycle on to one of the bikes I own. Meanwhile, I have perfect fitting spacers, and never broke a bolt. The poor fitment and looseness between the points of contact allow for the shaft to experience high stress in localized regions, and over time the metal fatigues enough it can break - especially low grade metal like the "steel" the axles are made out of.
 
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