Specialized Stumpjumper conversion recommendations

General Discussion about electric bicycles.
HrKlev   1 kW

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Re: Specialized Stumpjumper conversion recommendations

Post by HrKlev » Jul 27 2021 3:33am

TNC wrote:
Jul 26 2021 2:51pm
HrKlev, from your post I take it that you also ride a dirt motor. I'm curious as to which throttle system for the mid-drive that you use. I was able to live with the universal Bafang thumb throttle, but the twist grip throttle put me back at home as a dirt motor guy. Like you, I rarely use the throttle. However, in those occasional, critical spots where an unexpected stall out starts to occur or just a step-up that isn't going to happen with pedal-only, the throttle is a pleasure.

On your statement that "there is no way around relying on the throttle to get around technical stuff", I think that may depend on the rider and what they're able to do with PAS only. I'm fairly new to emtb's but not MTB's. I notice the more I ride this mid-drive Nomad, the more I get used to what PAS is capable of vs. my old pedal-only routine. Depending on how one has the program tuned, and which display level one selects, the PAS is pretty effective if you're in the right rear cog...that part not being any different from pedal-only off roading.

Of course it would be pretty presumptous of us to think our individual riding preferences, bikes, and components would fit every rider out there...LOL! We know better. Rider skill, age, and type of bike all come together to make the options all over the board.
Yeah, I have a dirt bike, that is not getting enough usage... I ended up with a thumb throttle on left side, together with the pas level buttons. So dropper post had to go to right side together with gear shifter. Did try out both half and full twist on my first bike with cadense pas setup. For the ability to apply the correct amount of throttle, the full twist was way above the rest, but I do not like to have grips that twusts on my pedal bikes (I hate grip shifts as well). So thumb throttle it was.

I am considering making it a push-button now that I have the torque sensor working like I want. Thinking it could apply like 100w or so for walk assist. But I havent decided yet. It was pretty sweet to have the throttle when the freewheel stopped working, so I could throttle it home...
Hubdrive as middrive, with torque sensing EMTB build: viewtopic.php?f=6&t=107622

6x6 conversion: viewtopic.php?f=34&t=109567

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Jul 28 2021 7:39am

I ride all sorts of bikes but I am 70% roadie, 20% MTB, maybe 10% recreational with the GF. Some racing back in the day but mainly hard competitive club riding, mountain tours, etc... although I am slowing down in my old age. :-( The key for me for good riding is to be able to maintain a steady human pace, what we call making tempo. Impossible with PAS that just gives a set amount of power even as the grade changes, the wind changes, etc. Or if I want to pick up the pace for whatever reason. There are many different scenarios but in most cases pedaling effort will necessarily have to change and/or one will have to shift PAS levels in addition to gears. Not saying is doesn't work and the bike won't get on down the road or up the mountain, but it simply is an unnatural way to ride. Torque sensors totally eliminate this problem. I can, however, see PAS perhaps being OK more for MTB than road since one is often constrained by technical terrain and the efforts are not as steady or prolonged... unless one is climbing a long fire road or somesuch. PAS is also fine for the cargo bike and recreational folks, I suppose.

The simplest way to put this is that I want the bike to adapt to me instead of me having to react to and adapt to the bike.
TNC wrote:
Jul 26 2021 9:43am
raylo, there's no "sorry" of any kind that needs to be attached to your statements. This is a discussion and often opinion forum, and the more info the better. As long as civility of some level is observed, there is seldom an absolute for every rider, for every ebike, and every condition. As I stated before, this is one of the sometimes confusing things on these ebike forums. I come from an exclusively off road MTB venue while others come from all manner of emotors and ebikes. I may work at a shop and ride a bicycle, but all experiences do not overlap.

raylo, if you don't mind, like I asked grant on another post, what is your main form of riding and what kind of bike(s) do you ride? To me, this tends to provide a better understanding of where each of us is coming from.

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Re: Specialized Stumpjumper conversion recommendations

Post by TNC » Jul 28 2021 10:13am

Thanks raylo...you're right about application and perspective being everything. Can I ask what ebike you're using? Your observation about climbing has some merit in certain situations. Where our shop's Trek Rail 7 demo bike always reflects the effort of the rider and the power output of the motor in a more consistent way, I think the PAS in a BBSHD can mimic that once one realizes a shortcoming.

After all my programming, I no longer get any...or at least none that I can feel through the cranks...on/off power impulses while accelerating, letting off, or being constantly on and off through trees or obstacles. In line with what you may be describing, I notice on a long climb...long for around here on an MTB trail...that you can out-pedal the PAS. Not sure if that's the right terminology.

On our favorite, close, local trail, the longest hill climb is called Hoover Hill. Before we even got the go ahead from the city to build this trail complex years ago, someone had wired an old Eureka vacuum cleaner to the fence post that was on the eastern property line. It was fitting because everyone jokingly said the climb "sucked"...not really that horrendous but it's relative...LOL! When we started building the trail, somehow Eureka Hill didn't have the pizzazz, so we called it Hoover Hill...a better sucking analogy...LOL!

Anyway, the climb is long and straight so you can stay on the cranks hard and steady because it's relatively smooth except right at the top. I can approach this climb in a very high PAS level, even up to 8 or 9...but...I notice that if I try to pedal like I was doing a pedal-only approach, the motor will do a quick on/off shutdown when I start really mashing on the cranks to speed up cadence. If I maintain a smooth, not so aggressive cadence, the motor will continue to deliver the appropriate power. The lower the gear selection, the lower the speed, and the lower the power delivery...like around "6"...the motor just happily powers along up the hill...with me pedaling of course. Now, this is not really so much a problem as it is a learning curve of using the programmed PAS. This does not appear to be something that you can program out. If you sort of try to out do the PAS on something like I described, I get that quick on/off event. Once I realized that, I just maintain cadence in the proper gear and go to town. Once identified, it hasn't been an issue. I do not notice that type of issue anywhere else while trail riding.

Now, the Trek Rail 7 demo bike isn't quite perfect either. It also seems to hit a spot where if you "try too hard" on the cranks in certain scenarios, it will diminish power to some degree...just not as noticeable as the BBSHD. But no doubt the torque sensing feature is much more smooth overall.

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Jul 28 2021 10:27am

I have a Cannondale F1000 hard tail with TSDZ2 and a Spec Stumpy XC with CYC Pro Gen2, both torque drives.

And I am not talking about the kinds of things you mention with dropouts and jerkiness... I am talking about even when PAS works smoothly. On a steady effort where something (terrain, wind, pace) changes you run up against the end of a level of PAS support since it is an on/off fixed amount and then your human effort must change... or you must also switch PAS levels. Doesn't make for a natural ride experience and hurts my performance. On the MTB I ride in very low assist, like 2 or 3 (out of 9) else I'd crash and burn on our technical trails. I can climb a tree with it. On longer smoother climbs it is just a matter of how fast do you want to go as to which assist level.

On the Cannondale I just did a group ride, had to stay in assist level 1 (of 5) to stay with the humans. I did shift up to level 2 on a 14% grade section but then the bike does weigh close to 50 pounds. On solo rides with the Cannondale on higher assist I can pretty much emulate a pedal bike ride with my human effort, it's just that the average speeds are higher. :-)

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Re: Specialized Stumpjumper conversion recommendations

Post by TNC » Jul 28 2021 3:37pm

Thanks for the info, raylo. It helps to know the background a little in some of these discussions. Man, you have a beef C'dale 1000 there. My Nomad is right a 50 pounds, but that's without a battery.

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Re: Specialized Stumpjumper conversion recommendations

Post by Chalo » Jul 29 2021 2:20am

raylo32 wrote:
Jul 28 2021 10:27am
I have a Cannondale F1000 hard tail with TSDZ2
[...]
I can pretty much emulate a pedal bike ride with my human effort,
Careful you don't get too enthusiastic about the human effort. Your TSDZ2 crank is likely to snap off at an inopportune moment.
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Re: Specialized Stumpjumper conversion recommendations

Post by TNC » Jul 31 2021 10:49am

raylo32 wrote:
Jul 23 2021 8:23am
But if I can find my old MTB backpack and want to try this can you point to an example of the "flex connection"?
raylo32 wrote:
Jul 23 2021 8:18am
But backpacks make me sweat even more than I already do. I hate backpacks. Part of my roadie background, I suppose. Now I DO wear a backpack when I take the Stumpy or TSDZ2 Cannondale on a beer and wine run. No getting around that... and it isn't very far.
Hillhater wrote:
Jul 23 2021 8:12am
For best bike balance and handling for trails, off roading, and serious downhill, pet the battery in a backpack with a flex connection down to the mid motor.
After 15 mins you will forrget you have a backpack and just enjoy a really light ebike ! :bigthumb:
raylo, here are a couple of pics of how I have my backpack set up and the cable attached to the bike. I've settled on 48" of 10ga wire with XT90 connectors that go from the Bafang Anderson pole connectors with an adapter from Luna...or...one can just make your own Anderson to XT90 cable that would be around 54-56" total length. Now, obviously all of this depends on the size of the bike to a degree and of course this if for a BBSHD motor.

I have some overkill on that spot on the seatpost in terms of the velcro ties and rubber wrap. This is where the biggest issue of wear would occur due to flexing. The main key to all of this is using automotive wire loom wrap available at most all auto parts locations...I think I'm using 3/8". This is a split material into which you can insert the two 10ga power wires. This wire loom wrap allows you to get as creative as you want. This wrap and quality 3M Super 33+ electrical tape keeps any sharp, flexing bends from occurring. 10ga wire itself is definitely robust, but minimizing chafing and hard bends, especially at the connectors, will insure long life. I built my cable from quality 10ga wire and XT90 connectors off of Amazon. This seatpost/saddle nose can be the spot where you design your "quick release" for the XT90 connectors, but I think it's better that you do it up at the pack. Why?...IMO there will be too much wear and flex over time with the cable dangling and bouncing at that point either at the seatpost or nose of the saddle.

At the backpack as you can see, the wire loom covered cable runs up through provided eyelets to the top where it connects to the battery pack in the backpack. This is a decently loose, smooth fit as you don't want the cable tightened down here. The battery lead with XT90 connector sticks out the hydration hose hole at the top and connects to the bike cable. This is a nice, smooth bend with no issue of chafing or kinking. While XT90 connectors are fairly tight, in my tests at home and at least two good, get-offs on the trail, the XT90 connector at the top of the pack pops right out. As long as the connectors are well soldered, I'm not seeing an issue here. And in a belt-and-suspenders kind of deal, I have an extra power cable coiled up in the backpack...but I think this is overkill.

As always, there is more than one way to skin a cat. I'm sure others have come up with equally successful methods for backpack battery and cable arrangements. This is how I did it, and after quite a bit of riding since April of this year, I've had no issues of failure. Just like the BBSHD motor itself, this has worked way better than expected. I ride in some technical trails requiring a lot of body english, standing, leaning, etc., and the cable coming off the nose of the saddle has not been a problem. It has not tangled in my knees/legs, and it has not been grabbed by vegetation or limbs. I'm as surprised as anyone...LOL!

Obviously a backpack battery solution is not for everyone, and if one has a frame that allows a properly sized battery pack, then that is a non-issue. I have two high quality, long travel MTB's that are designed in a way that won't readily accept a frame mount battery. On another note, my MTB's are burly, heavy bikes with dual crown forks, coil rear shocks, and big wheels/tires. I kind of like not having that extra weight on the bike. Still, people are different, bikes are different, conditions are different. This is just one option.
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Re: Specialized Stumpjumper conversion recommendations

Post by HK12K » Jul 31 2021 12:11pm

The thought of strapping the thing most likely to potentially burst into flames should the worst occour directly to my body is not a particularly appealing one to me. Sure, you can probably take it off quickly if need be... unless you're injured or unconscious.

That said, sometimes ya gotta do what ya gotta do. Different strokes for different folks and all that.

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Re: Specialized Stumpjumper conversion recommendations

Post by Chalo » Jul 31 2021 10:52pm

HK12K wrote:
Jul 31 2021 12:11pm
The thought of strapping the thing most likely to potentially burst into flames should the worst occour directly to my body is not a particularly appealing one to me. Sure, you can probably take it off quickly if need be... unless you're injured or unconscious.

That said, sometimes ya gotta do what ya gotta do. Different strokes for different folks and all that.
Yeah, it does make me think of some dude who's so fixated on lightening his dirt bike that he carries a five gallon jerrycan of gasoline on his back, so he can be leave the tank off his bike.

Like, I see what you're getting at. But you are still missing the point.
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Re: Specialized Stumpjumper conversion recommendations

Post by markz » Jul 31 2021 11:19pm

Careful you don't get too enthusiastic about the human effort. Your TSDZ2 crank is likely to snap off at an inopportune moment.
Thats gotta suck, walking home with a non operative ebike.
I broke a chain once on my Cyclone mid drive, had to call Eagle 1 for a pickup :lol:

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Re: Specialized Stumpjumper conversion recommendations

Post by LewTwo » Jul 31 2021 11:28pm

markz wrote:
Jul 31 2021 11:19pm
Thats gotta suck, walking home with a non operative ebike
it does regardless of bike and the further away the more it sucks.

The other thing I have never understood is the logic of having the seat raised up to elbow height or beyond. In the referenced video there is a sequence of the dude going up an incline. He can not even get his feet on the pedals ... much less the ground. Worse I can only imagine what part of one's anatomy all his weight is resting on ... ouch! Different strokes .....
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Re: Specialized Stumpjumper conversion recommendations

Post by Chalo » Aug 01 2021 12:33am

LewTwo wrote:
Jul 31 2021 11:28pm
The other thing I have never understood is the logic of having the seat raised up to elbow height or beyond.
It's not seat height off the ground that matters; it's seat height off the pedal. The higher the bottom bracket, the shorter the cranks-- the higher the seat must be to get correct leg extension.
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Re: Specialized Stumpjumper conversion recommendations

Post by Hillhater » Aug 01 2021 1:31am

Chalo wrote:
Aug 01 2021 12:33am
It's not seat height off the ground that matters; it's seat height off the pedal. The higher the bottom bracket, the shorter the cranks-- the higher the seat must be to get correct leg extension.
Remember, we are taking off road Ebike here, not circus acts or max performance road racing.
Seat height to the ground is more important than correct leg extension in many situations, with the extra weight of an Ebike in off road situations.
Even with unpowered bikes low seat height can be an important advantage.....if you have just watched the Olympic BMX finals !
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Re: Specialized Stumpjumper conversion recommendations

Post by HK12K » Aug 01 2021 9:56am

This is why dropper seatposts were invented.

When the going is not rough proper leg extension offers a myriad of benefits with few drawbacks. However when you're offroad and are standing on the pedals and shifting your body all over the place to distribute weight where you need it to be to maintain control, that seat is very much in the way. If you want to have your cake and eat it too, the seat position needs to adjust on the fly.

I'll put a dropper on my Raptor eventually, if I can bring myself to drop that kind of coin on a seatpost.

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Aug 01 2021 4:22pm

And don't forget a dropper post makes it easier for us old guys with dodgy hips to mount and dismount. I could use a couple on my bikes. One of these days...
HK12K wrote:
Aug 01 2021 9:56am
This is why dropper seatposts were invented.

When the going is not rough proper leg extension offers a myriad of benefits with few drawbacks. However when you're offroad and are standing on the pedals and shifting your body all over the place to distribute weight where you need it to be to maintain control, that seat is very much in the way. If you want to have your cake and eat it too, the seat position needs to adjust on the fly.

I'll put a dropper on my Raptor eventually, if I can bring myself to drop that kind of coin on a seatpost.

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Re: Specialized Stumpjumper conversion recommendations

Post by markz » Aug 01 2021 7:34pm

Maybe you just need a ladies step through frame and your hips and joints will thank you for that, then that creates a problem of where do you place the battery. The Townie ebikes at the lbs had a rear hub and slide in rear rack battery.
I havent fallen yet from stepping over a mens frame, but came close. Its primarily at the end of the ride when tired.

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Re: Specialized Stumpjumper conversion recommendations

Post by Hillhater » Aug 01 2021 8:33pm

Many of the recent and current “mountain bikes” ..off road, downhill, etc etc ..are designed around a “Compact” frame design.
Basicly a frame with a short upright seatpost tube. They require a long seat post to achieve “ full leg extension” and are intended for use with the dropper seat posts... but lend themselves to easy leg to ground action if desired.
Personally , i believe the best solution is a “pedal forward” cruiser type frame with suspension and a big comfy seat ...like the Day6 designs.
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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Aug 02 2021 5:19am

No I am not THAT far gone yet! My road racing bike is OK, I can lean the bike and swing my leg over without too much pain... same for my full suspension MTB conversion Specialized. The worst one by far is my Cannondale hardtail that I converted to e-bike. Combined with my already high seat height (long inseam) the BB height on that one is higher than the other bikes so the leg swing over the saddle when one foot is on the ground is more difficult. That one will get a dropper post first though since it is 27.2" post the selection is smaller... currently looking at PNW post. (https://www.pnwcomponents.com/collectio ... opper-post) Maybe the Specialized next. Never on the road bike. That one needs to stay light.
markz wrote:
Aug 01 2021 7:34pm
Maybe you just need a ladies step through frame and your hips and joints will thank you for that, then that creates a problem of where do you place the battery. The Townie ebikes at the lbs had a rear hub and slide in rear rack battery.
I havent fallen yet from stepping over a mens frame, but came close. Its primarily at the end of the ride when tired.
Last edited by raylo32 on Aug 02 2021 5:24am, edited 2 times in total.

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Aug 02 2021 5:20am

duplicate

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Aug 02 2021 7:52am

Yes, my weight is WITH battery and it may be a bit less than 50, I haven't actually weighed it. I just use 50# as a guestimate. But the base bike was around 25 # IIRC... TSDZ2 is about +8, super shark battery is about +10, cheaper RockShox fork with coil spring instead of air is maybe +1, rear rack is maybe +1, home made EGO battery mount maybe +1/2, wire bead tires and heavy puncture resistant tubes maybe +1/2, big grips + 1/4, etc, etc. One of these days I'll weigh it.

Thanks for the photos of your backpack setup. I have some of that split plastic cable protector around from car audio and alarm installs. Maybe I'll give that a try one of these days. But I do hate riding with backpacks.
TNC wrote:
Jul 28 2021 3:37pm
Thanks for the info, raylo. It helps to know the background a little in some of these discussions. Man, you have a beef C'dale 1000 there. My Nomad is right a 50 pounds, but that's without a battery.
Last edited by raylo32 on Aug 02 2021 8:44am, edited 2 times in total.

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Aug 02 2021 8:05am

LOL... Possible, I suppose. Even though I am not Chalo size I don't do anything extreme like stand and sprint on it which might compromise the cheap BB spindle. I save that sort of stuff for the road bike with D/A cranks. My only issue with the TSDZ2 so far is that it creaks just a little under high human effort in a big gear. Not the crank arms but something in the mounting. I would never accept that on my pedal bikes but on a cheap e-bike conversion I find it only mildly annoying... but one of these days I might look into ways to eliminate that.
Chalo wrote:
Jul 29 2021 2:20am


Careful you don't get too enthusiastic about the human effort. Your TSDZ2 crank is likely to snap off at an inopportune moment.
Last edited by raylo32 on Aug 02 2021 8:46am, edited 1 time in total.

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Aug 02 2021 8:30am

ALWAYS carry a chain tool. Back when I was young and foolish doing solo MTB rides in Crested Butte grizzly bear back country (!) at least I wasn't so foolish as to not carry a chain tool, that I ended up needing to get back one day when my chain failed. Now if the 219h motor chain broke on your Cyclone (and like on my CYC bike) that could be a problem. Regular narrow bike chain tool isn't going to work on that.
markz wrote:
Jul 31 2021 11:19pm
Careful you don't get too enthusiastic about the human effort. Your TSDZ2 crank is likely to snap off at an inopportune moment.
Thats gotta suck, walking home with a non operative ebike.
I broke a chain once on my Cyclone mid drive, had to call Eagle 1 for a pickup :lol:

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Aug 04 2021 9:39am

I have a MTB backpack somewhere and I have an extra shark battery mount... I also have some of that 12g flex wire around. So I am going to give TNC's flex connector a try with my Stumpy. I am afraid to hit any of the real rough stuff with my under down tube mount shark battery setup, even with it supported by straps and tape. It is fine on the road and smoother trials up to and including some log crossings, but may not be up to bashing though the toaster oven size granite rocks we have around here... although I am not sure how much of that I will do on this bike since it has a bit of delay in the torque sensing which makes it more challenging. Interesting that my TSDZ2 bike on OSF has pretty much instant power delivery, but that bike is set up strictly for the smooth stuff.

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Re: Specialized Stumpjumper conversion recommendations

Post by raylo32 » Aug 04 2021 3:33pm

Battery flex cable made up, no picture but it looks a lot like yours, TNC. I really need to get some more wire and make a neater one. The only XT connectors I have have pigtails and butt soldering these wires is a PITA and hard to get a neat result. But it works... and I found my CamelBak pack. Maybe give it a test ride tomorrow.

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Re: Specialized Stumpjumper conversion recommendations

Post by TNC » Aug 04 2021 6:05pm

Good luck with your test, raylo. Maybe some here and elsewhere think I'm trying to sell the concept of backpack battery setups for mountain biking. I'm not. But I do try to diminish some of the myths about them. We all know that there is no one-size-fits-all when it comes to just about anything.

I got my XT90 connectors from Amazon, and they're the same Amass brand/model that Luna uses for 10ga wire. On your observation about battery mounting with the on-frame mounts, looking at many that come through the shop on MTB's with aftermarket batteries, I agree that they don't look that secure or rugged. Guess that's why most factory built emtb's like Trek, Spec, and even the Luna X1 and others use in-frame mounting. I'm sure there are some solid external mounts out there somewhere.

Here's one of the main trails I ride in my area, and this isn't the most rugged one. But you can still tell it has rock gardens and such that will flat out shake a bike apart. Just watch the guy's GoPro shaking...LOL! Let us know how the test works out.

https://www.youtube.com/watch?v=PzvAydHEExc

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