“…they were not originally designed for…”. Conclusion??

DingusMcGee

10 kW
Joined
Feb 23, 2015
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Location
Laramie, WY
Recently I seen this message from an eBay seller:


New message from: re.cycle.d.mountainracing (2,953RED_STAR Star)
“Hello -
Our basic expectation is 24h for a response, this expectation is stated in all our listings
glad you found something, we understand we dont win every sale

In general we do not support MTB to high power e-bike conversions because of the numerous safety issues that arise from using the frames in application that they were not originally designed for - Ride at your own risk

Regards, Keyth”

9FCE7B59-BF72-438D-BFF5-E01CF9C1E1B9.png

Note the wording “…they were not originally designed..”. We Ebike DIY builders frequently hear a similar repeat of the quoted phase. Such phrases similar to this one likely mean “bikes were not designed [to be used for?] as an Ebike”. In world of meaningful verbal exchange this statement is the premise of an argument. The argument form used here is called “begging the question” or Circular Reasoning and is fallacious. What question? The begging question is ,”So what is your conclusion?” The speaker of such phases expects you to knows his conclusion that he does not state.

From that premise some conclusions might be they then are unsafe after conversion. Or a lesser conclusion would be they are unsuited. How so? We modify them. E.g. put better brakes and tires on the bike. Usually no substantiation of assertions happens.

The arguments that address suitability or unsuitability are never stated. Such conversions of bikes to Ebikes makes them something partially out of the category of generic bikes.

Again on the eBay chat: Keith after the stating the design premise goes on to state what may seem to be a conclusion: [therfore] …’they have “safety issues”’. This statement is just another case of begging the question. Your question to ask is, “What are the safety issues? What is your substaniation?”

Such is talking with Nerds?

Hoorays for Suchness…..Continue Navigating — with numerous frame safety issues?
 
I think it's a fair position for a company to take. In terms of frames you have steel, aluminum, and carbon. Only the former is really strong enough to take some of the ridiculous 10-20kW motors people are slapping on them, torque arms or not. And many people are too lazy or cheap to even include torque arms.

Also note they said "high power eBikes", so it doesn't sound like they are complaining about slapping a tiny 250W hub on somewhere. The dangerous things a DIYer does are one thing, that's your own responsibility, but as a company, telling people you can put a 10,000W motor on any frame is just inviting injury lawsuits.

Then if we're talking about mid-drives instead of hubs, the situation gets even worse because now you are putting that power through a chain and gears that were never designed to take that much.

Once your bike starts going that fast there's a lot of other stuff you need to do to stay safe as well, like add headlights that reach farther in the dark to see obstacles before your faster bike runs into them, and switching to hydraulic brakes so you can still stop fast enough from the higher speed. As a company, you can't guarantee your customers are going to do these things, so it is better not to recommend.
 
Probably just a disclaimer to (try to) ensure they won't get sued or need to replace a frame that was used for DIY conversion. IMO, if I were a frame builder or sold frames constructed by others, I would add the same disclaimer. Possibly a minuscule part of their market anyway.
 
Inanek,

You say, “ chain and gears that were never designed to take that much.” So, what is your conclusion from this premise? How much chain tension? is too much and what kind of serious problems arise from a chain break? Thanks for begging the question….,.

As for my chain breaks, the motor has spun the chain ahead and out of the harms way.

If the store agent says because of liability, the topic then leaves the arena of the original design premise and becomes a statement of beliefs he wants to assert. He may not allow your purchase.

As for a disclaimer, it can be stated and upheld without any claim. You have to sign this release to get the products.
 
I have seen conversions that would be fine for even a fragile performance oriented bike. I've also seen conversions that ruined the bike they were inflicted upon.

To me it makes perfect sense that a retailer would dissociate himself from the potential folly, poor judgment, and poor workmanship that an unknown yahoo might try to seek redress for, when the problem was none of the retailer's doing.
 
Chalo et al,

The point of my post was not about vendors and what they can sell but about the illogical reasoning methods that do get used to justify putting down bike to ebike conversions.

The statement “bikes were not designed to be ebikes ” is likely quite true but carries no weight in determining the suitability or unsuitability of modifying a bike to an ebike.

When presented in this fashion where the statement is given as true obvious evidence (the premise) and followed by no evoked conclusion, we are left to ask a question like “So does this (premise) preclude modifying a bike in some fashion to get an ebike?”

A different item used with begging the question:

Fuel Cells were invented /designed for electric power for use in the USA first moon mission.

Now supposed I say, “Fuel Cells may soon power our truck/freight fleets.”

A heckler says,”they were never designed for that” . He sort of thinks some past design history makes a new use unsuitable.

The heckler is begging the question: How so?
 
DingusMcGee said:
Chalo et al,

The point of my post was not about vendors and what they can sell but about the illogical reasoning methods that do get used to justify putting down bike to ebike conversions.

The statement “bikes were not designed to be ebikes ” is likely quite true but carries no weight in determining the suitability or unsuitability of modifying a bike to an ebike.

When presented in this fashion where the statement is given as true obvious evidence (the premise) and followed by no evoked conclusion, we are left to ask a question like “So does this (premise) preclude modifying a bike in some fashion to get an ebike?”

A different item used with begging the question:

Fuel Cells were invented /designed for electric power for use in the USA first moon mission.

Now supposed I say, “Fuel Cells may soon power our truck/freight fleets.”

A heckler says,”they were never designed for that” . He sort of thinks some past design history makes a new use unsuitable.

The heckler is begging the question: How so?

I'm a fan of this line of thinking. Are you suggesting that the ebay seller, and many others, find it hard to think out of the box, yes?

I also like your fuel cell analogy. To take it further, look at cars. When powered 4-wheel transportation was being worked on in the late 1800's approx 1/3 were electric, 1/3 were steam, 1/3 were gas. Now they're all gas, for plenty of reasons that are discussed in other threads. So following your line of thinking, when someone says, "Cars were never designed to be electric!," you can come back at them with, "sure they were!" I like it.
 
harrisonpatm said:
So following your line of thinking, when someone says, "Cars were never designed to be electric!," you can come back at them with, "sure they were!" I like it.


That is not the same logic.
A more correct car analogy would be: "That Trabant only had 20hp from the factory, it wasn't designed to handle your 300hp engine swap!" And they would be correct. You'd need to change just about every drivetrain, brake and suspension component, just for it not to kill you immediately.
 
eee291

Says:
A more correct car analogy would be: "That Trabant only had 20hp from the factory, it wasn't designed to handle your 300hp engine swap!" And they would be correct. You'd need to change just about every drivetrain, brake and suspension ….

In your above assertion the premise is “that Trabant only had 20 hp from the factory” your stated conclusions follows….. This is not an example of begging the question. It is an argument with a premise (evidence ) and a stated debatable conclusion. In the case of bike design “begging the question” the premise is stated and without saying anything about how the speaker thinks that his unstated conclusion is obvious and a sound argument — maybe his conclusion is “therefore bikes are unsuited for for any conversion to an ebike?

Back to your example: I ask, could the vehicle be modified to handle 300 hp? If so, it may not be unsuitable.

After modifications an item sometimes goes by another name. E.g. bikes get modified to become called ebikes. Aluminum structural forms get modified to make and be called bike frames. Can one argue aluminum structural forms were not designed to become bikes?
 
eee291 said:
harrisonpatm said:
So following your line of thinking, when someone says, "Cars were never designed to be electric!," you can come back at them with, "sure they were!" I like it.


That is not the same logic.
A more correct car analogy would be: "That Trabant only had 20hp from the factory, it wasn't designed to handle your 300hp engine swap!" And they would be correct. You'd need to change just about every drivetrain, brake and suspension component, just for it not to kill you immediately.
That's fair. I was generalizing for sure
 
Don't forget 2,953RED_STAR maybe bias against anything powering a bike outside of a human. Remember that's cheating as they say. See this often.

The first powered bikes have matured they are called motorcycles now.
does anyone know what get's better mileage than a E-bike?
 
ZeroEm,

I have heard that the cost of the extra food you eat for pedaling a bike a mile exceeds the cost of charging bike batteries for a mile of use.


Cheating
Then Yeah, I like this form of cheating. I get that squawk less now that I blow by ‘em at 45 mph. “Was that a motorcycle?”
No. Just an ebike, I can tell by the [unsuitable] design.
 
DingusMcGee said:
ZeroEm,

I have heard that the cost of the extra food you eat for pedaling a bike a mile exceeds the cost of charging bike batteries for a mile of use.

I would love to see the math on this. Not just because I think it's true, but because it can be verified quantifiable. "I have heard" is an anecdote, but I bet the math is doable. I don't have the time for it myself currently, but calories are just another form of energy.

Google says 1 calorie = 4.18 watts.
 
It's not just cost, but energy economics that seem to favor e-bikes over pedal-only bikes. Just the energy required to produce food and bring it to market exceeds the electrical energy required to propel an e-bike and rider a given distance and speed.

However, when you try to account for the money and energy costs of treating diseases that result from idleness, pedal bikes start to look more economical again. It's hard to quantify, though.

I consider either way to be correct when compared to other options.
 
Chalo said:
However, when you try to account for the money and energy costs of treating diseases that result from idleness, pedal bikes start to look more economical again. It's hard to quantify, though.

For sure. Though that's taking into account prioritization of cost and benefits that you come up with. Same thing here:

Chalo said:
Just the energy required to produce food and bring it to market exceeds the electrical energy required to propel an e-bike and rider a given distance and speed.

You're totally not wrong. I'm just thinking as a hypothetical, scientific, admittedly narrow comparison, what happens when you ignore the total efficiency cost, and focus purely on the movement? What I'm wondering is, how many calories does it take to pedal a mile, and how many watt hours does it take to propel a same weight bike and rider the same distance?

I don't know the answer, just wondering out loud.
 
> bikes were not designed to be ebikes

There seem to be a lot of straw man arguments getting tossed around here. The very bottom of the screenshot in the OP indicates we're talking about putting a 10,000W motor on a previously human powered Brodie here.

My ebike has a 750W motor. If I don't care about saving battery, turn on max field weakening, etc. I can reach 30MPH. Do I think my bike's frame can take 13x the power without folding at some point and dumping me? Nope. Do I think it can safely go 60MPH with a bigger motor? Nope. Is it still an ebike? Yep.

If you really want to turn a human powered bicycle into a dirt bike, it is possible. I think you'd have to cut the tubes in half and put steel plate through them, then weld back together, cut off the back and put a dirt bike swing arm and suspension on there, etc .
 
lnanek said:
> bikes were not designed to be ebikes
The very bottom of the screenshot in the OP indicates we're talking about putting a 10,000W motor on a previously human powered Brodie here.

Yeah, if I were a vendor (of bikes or of electric motor kits), I'd want to put as much distance as possible between my business and this kind of hugely foolish project.
 
People have been stuffing too much power into vehicles not meant for it since the days of steam, motorcycles were originally bicycles that they hung motors on, and then strengthened what broke, and when the next thing broke, they strengthened that, and then the next thing...

It's wise for any manufacturer to say "We don't cover stupid mods to our product."

An e bike conversion to a pedal bike had better not put any stress on the frame, wheels or driveline that's more than 50% over what a strong, heavy rider might load it with. The brakes had better be up-rated to handle 100% greater braking forces (more weight X more speed)

I suspect that the current wave of dual battery/dual motor production Ebikes is mostly an effort to cheaply distribute loads in such a way that conventional bike components can handle them reliably.
 
Okay a preview of a hugely foolish project:

93AB4F91-0297-4943-897D-04982190C9CE.jpeg

Ianeck, we have listened to your straw man arguments about design criteria. Look at the frame in the above pic and tell me where does sigma(max) exceed 0.3 Sigma(yield)? You are on the mat. Can you defend yourself?

E0AAD621-9BEC-4DB4-B2B9-44228FEE96A9.jpeg


8355503C-4BC0-4E50-91E2-1FB8F9DD0BE2.jpeg


F8FD0B76-6575-4AE5-84C9-73731B7E78D7.jpeg

I see no seat belt restraints on any of these motor powered craft. They are designed to be unsafe. Ride only if you have the skill-sets.. Chalo? We don’t need rock-free groomed trails.

Warrantees? Vendors: we modify the weak bike junk you sell to make it sufficiently strong to create a suitable product. — you do have reason to be worried about the weak crap you sell.

Stay away from Delaware if you are just pedaling.
 
lnanek said:
Do I think my bike's frame can take 13x the power without folding at some point and dumping me? Nope. Do I think it can safely go 60MPH with a bigger motor? Nope. Is it still an ebike? Yep.

This is a benefit that I realized after the fact on my motorcycle conversion. I took a vehicle (tires, rims, frame, swingarm, shocks, ect) that was built to handle 100-120mph, and I've brought it down to 65mph top speed. I like not worrying about whether my frame can take what I'm giving it.
 
LewTwo,

Circa 1972: Scientific American had an article about the most efficient forms of motion. The best of birds was not #1, but the best was a close tie between a human powered bike and a jet liner. The Ebike forms were not in vogue at this time.

Soaring birds take advantage of thermal cells. They detect cells of rising air — ride them — and get an almost effortless gain in elevation. Then they glide “downhill”. Find another rising thermal and repeat the cycle.

Motor less aircraft do the same thing. The distance record for glider flight is over 3000 km. Achieved by riding thermal cells.
 
The poor judges of bike frame quality are out there and sometimes get feedback from their poor choices.

Circa 1986: In the mountains I found a downhill gulley trail with a non visible 6 feet of AIR — Yikes. The landing area was big, flat and free of nearby hazards. You had to go through it. I had a Specialized Hardrocker hard tail MTB and ran the gulley maybe a dozen times — no frame cracks. Rock Shoxs came later. A friend bought a new top-end Nishiki hard tail MTB. He was up for a ride but did not get any preview of this one. On the maiden voyage the Nishiki MTB fork buckled far outward on the first landing. The BB was almost touching the ground. Can I say, some vendors sell crap?
 
DingusMcGee said:
Motor less aircraft do the same thing. The distance record for glider flight is over 3000 km. Achieved by riding thermal cells.
... but it generally takes a lot of power from another aircraft to get them airborne to begin with :wink:
 
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