If you ever wondered "Will a Shinko 714 stay on the wheel after a tube blows?"

H

HK12K

100 kW
Joined
Jul 24, 2019
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The answer is no. No it will not.

Tube let go leading to a massive tankslapper. Kept it upright for far longer than I expected, fighting the impulse to hit the brakes the entire time. Ended up going off road and dumped it in the gravel a few feet before slamming into a pole. Jumped up in a cloud of dust.

Got some rash on my elbow, forearm, and a bit on my leg. Got off reallllly lucky all considered. Thought I was going to highside my skull into the asphalt.

Didn't hit my head at all, but seriously considering a helmet now.
 
Yeah but how fast were you going?

HK12K said:
The answer is no. No it will not.

Tube let go leading to a massive tankslapper. Kept it upright for far longer than I expected, fighting the impulse to hit the brakes the entire time. Ended up going off road and dumped it in the gravel a few feet before slamming into a pole. Jumped up in a cloud of dust.

Got some rash on my elbow, forearm, and a bit on my leg. Got off reallllly lucky all considered. Thought I was going to highside my skull into the asphalt.

Didn't hit my head at all, but seriously considering a helmet now.
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Initially? Around 40mph, downhill. By the time I stuffed it, less than that. How much less? Idk, didn't check the speedo.
 
Until you find a helmet you really like, a cheap skater helmet is a good starter, and backup...you might even find it dirt cheap in a thrift store.

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Have absolutely considered skate helmets. Good rear of head protection. I might just go balls out and get a full face dh or mx helmet, if I can find one that's palatable.

No down time. Picked myself up, made sure I wasn't torn up too badly, then picked up the bike and pushed it home. Crooked handlebars and tire a floppin. Getting the blown tube out was easy since the dismounting was already done for me. Cut it free with an olfa and used a piece of it to patch another tube I had lying around until the ones I just ordered arrive on Sunday. We'll see if the ghettopatch holds, if not no biggie.
 
why did the tube blow?
 
Rough spot on a spoke hole is my best guess, or simply defective tube. Both the tire and tube were brand new.

Ordered a fresh rim strip, along with new tubes. Though I may just hack this tube up and silicone it to the rim to help ensure this doesn't happen again.
 
What thickness of motorcycle tube was it, Ultra Heavy Duty or Heavy Duty or the Regular tube?

HK12K said:
Rough spot on a spoke hole is my best guess, or simply defective tube. Both the tire and tube were brand new.

Ordered a fresh rim strip, along with new tubes. Though I may just hack this tube up and silicone it to the rim to help ensure this doesn't happen again.
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You might want to upgrade to UHD, not sure what the weight difference is between the two. Quick searches came up with thickness and weight from Amazon item.

Regular 1.2mm
HD can be 2-3mm
UHD is 3.5-5mm but usually 4mm thickness @ 3.25lbs (80/100-21)
 
HK12K said:
Have absolutely considered skate helmets. Good rear of head protection. I might just go balls out and get a full face dh or mx helmet, if I can find one that's palatable.
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Would you have been equally sharp and capable of dealing with your situation if your head had been overheated from riding with it shut into a styrofoam box in summer?

I feel like having my wits on point is safer than having my head in a box, but others may differ.
 
Chalo said:
HK12K said:
Have absolutely considered skate helmets. Good rear of head protection. I might just go balls out and get a full face dh or mx helmet, if I can find one that's palatable.
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Would you have been equally sharp and capable of dealing with your situation if your head had been overheated from riding with it shut into a styrofoam box in summer?

I feel like having my wits on point is safer than having my head in a box, but others may differ.
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A valid question, but considering how helplessly out of control I was at the time the vision of my head bouncing off of the asphalt was front and center. If I do choose to purchase a helmet ventilation and visibility will be of top priority. I do not do well in the heat. Today was a scorcher too.

I should probably just slow down.

If these next tubes let go I'm filling the frocker with spray foam.

(Kidding. Maybe.)
 
So, blow out riding 40mph downhill! was it front or rear?

Personally I don’t believe the tire was the problem. I mean presumably, any tire of the same size would have done the same. Some situations can pop a flat tire off the rim at 40 mph, even with foam inserts and/or rim locks. A blow out on the front riding downhill is very hard to recover control.
 
It was rear and the tire was not at fault at all. It was a very tight fit during installation and I was surprised it unseated. Presumably a combination of the rapid release of air from the tube combined with whatever other physics involved created a perfect self changing tire storm.

I am both lucky and grateful it wasn't a front blowout. I wouldn't have had a chance.
 
A rear blow out requires front braking to unload the rear. The front is very counter intuitive because it does require a wheelie and really, who has the nerves to pop a wheelie riding 40 mph downhill?
 
I recently replaced the front fork with one that does not have provisions for rim brakes and haven't put together a disc capable 20" front wheel as of yet. I've been relying on variable regen via the Nuc, which has worked very well at bringing the bike to a stop this far. Obviously under the circumstances grabbing that lever would have meant certain disaster.

I have never had the rear end of a vehicle swing as wildly or as far out of line as this bike did today. Like a pendulum on speed. A definite eye opener. Clearly I'm going to need to find a front brake solution sooner rather than later, but considering the speed, decent, and tail happiness I suspect applying any braking at all would have had some undesirable consequences.

Got a couple days to think about it. The patch I applied to a previously used tube didn't hold, so I'm down and out until Sunday at least.
 
UHD tubes cost $40-45usd from a motorcycle dealer, otherwise add $20 for shipping online (ebay).
Triple up the rim tape and get good quality rim tape.
Take a look and see if any spokes were sticking out the top of the nipple.
Were you using the tire clamp that bolts the tire to the rim?

Slow down! :wink:
Were you late getting somewhere?


Got a couple days to think about it. The patch I applied to a previously used tube didn't hold, so I'm down and out until Sunday at least.
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Ahhhhhhhhh that absolutely sucks big time, I hate when breakdowns like that leave us out of ebiking for even a day. Luckily you dont have to wait for any hub motors or controllers that you dont have spares for. Unless you can grab them locally for decent price if prices matter by this point.
 
No matter how you find that regen is doing good, it is the front that makes a short braking distance, and a huge difference with rear braking.
 
we could start you a Go Fund Me for one of these
lots of padding :D

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Will look into the uhd type if I continue to have issues, though hopefully that won't be the case. Hopefully.

I'll have a really close look at the wheel whilst rewrapping it, but it's double wall so the spokes are a ways away from the tube... Unless there is something especially fucky going on. No rim clamp as this wheel doesn't have a provision for it. I see why they exist now though, lol.

Glad I won't have to wait too long for the tubes. According to Amazon they're nearby, though being handed over to the postal service, so we'll see how that plays out.

I realize the front brake is important, but the bike is a work in progress. It's on the list for sure, but sourcing an off the shelf disc compatible 20" wheel is easier said than done. A few weeks ago this thing had a 250w Hilltopper kit up front with a rigid fork. Now a suspension fork up front and a leaf motor in the rear. Only enough time and money for so much, and this sucker is my commuter so downtime is less than ideal. Then again so is coming off the thing at speed. Just turned 44, I'm getting too old for those kind of shenanigans. :lol:
 

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You were riding 40 mph downhill on a Giant Revive ? :D

I am roughly 30 years older than you, yet not old enough to give up speeding the mountain trails on a DH bike. But, even 40 years ago I wouldn't have been crazy enough to ride 40 mph on a Giant Revive.
 
You would be surprised at how stable it is at speed! I certainly was.

In stock-ish configuration, at low speeds, the handling was super sketchy. Once you got going it was better but still a bit too twitchy. Once I replaced the oem rigid fork with the moderately taller suspension one and stuck the slightly taller tire up front it increased the rake enough to make it quite stable indeed.

...when there are 2 tires attached to it anyway. :lol:

Holy moly that was terrifying. :confused:
 
MadRhino said:
You were riding 40 mph downhill on a Giant Revive ? :D

I am roughly 30 years older than you, yet not old enough to give up speeding the mountain trails on a DH bike. But, even 40 years ago I wouldn't have been crazy enough to ride 40 mph on a Giant Revive.
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OMG!...a sudden flat/blowout on that ebike, at that speed, with those tiny wheels? I know well that Chalo doesn't like helmets, but OP, if you're going to be doing high speeds on that bike...you need a helmet...LOL! And you know what? I hear helmets also work when you're hit by a cage driver. :mrgreen:
 
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