A seller told me the Ryde Andra 40 is not a suitable rim for a 1000w hub motor. Is that true?

[ebike4healthandfitness]

The only way they can contribute to in-plane stiffness is to resist the rim's tendency to deflect outward on either side of the loaded section (those couple of spokes in the diagram above that show positive values around 40 on the scale), when that's only a tiny fraction of the deflection that's happening.

Chalo, that diagram your are referring to comes from an article (post #14) where the results were obtained by computer simulation. The computer simulation fails to properly account for the fact that the tire is a pneumatic device. When a tire encounters a load the pressure in the tire increases distributing the load throughout the wheel. This distribution of load throughout the entire wheel (via increasing air pressure) is why the tensioned structure of a wheel is able to increase radial stiffness by increasing spoke count.

The way he did the simulation is way too simplistic with way too much force concentrating in way too small of an area.....as if the bike was riding directly on the rim without even an inflated tire present.

 

[Chalo]

Tires are flexible. They apply a constricting force on the rim when inflated, and they distribute point loads a little more evenly than if they were solid rubber. But they don't add rigidity to the system, because they don't have any to add.

You can confirm Ian's analysis yourself by plucking spokes to illustrate changes in tension (or by using a tensiometer). Loaded versus unloaded, you will only notice large tension excursions in the zone immediately above the contact patch.

 

[ebike4healthandfitness]

Tires are flexible. They apply a constricting force on the rim when inflated, and they distribute point loads a little more evenly than if they were solid rubber.

Pneumatic tires don't distribute point loads a little more evenly than a solid rubber tire....they distribute point loads a huge amount more evenly than a solid rubber tire.

In fact, no doubt solid rubber tires would be incredibly hard on a spoked bicycle wheel.

Here is what Sheldon Brown says about air-less tires:

Sheldon Brown: “Airless tires have been obsolete for over a century, but crackpot ‘inventors’ keep trying to bring them back. They are heavy, slow, and give a harsh ride. They are also likely to cause wheel damage due to their poor cushioning ability. A pneumatic tire uses all of the air in the whole tube as a shock absorber, while foam-type ‘airless’ tires/tubes only use the air in the immediate area of impact. . . My advice is to avoid this long-obsolete system.”

But they don't add rigidity to the system, because they don't have any to add.

Of course a tire doesn't add rigidity to the system. The job of a tire is to compress which the opposite of adding rigidity. And when the tire compresses the pressure in the tire increases everywhere . Even the rim and spoke at the top of wheel feel the wheel's contact with the ground through this pressure increase caused by the tire's contact with the ground.

 

[99t4]

I was kinda trying to stick with overengineered 12g spokes since that's what came with it and my hub has the holes drilled for 12g.

OP, looks like you are falling into the common misperception that thicker spokes are better. Easy mistake to make, as they certainly look stronger, and somewhat makes sense logically at first glance.

Spoked wheels physics are quite complex, yet well known by now.

Many of us have found the sweet spot for our hubmotor wheel builds with 14g double-butted spokes and rims similar to your prospective Andra 40. Results in many thousands of miles good riding, good performing, reliable wheels.

Sapim Strong Single Butted J-Bend Spoke

A butted spoke is drawn to its specific profile, which defines its high strength. The strongest spoke in Sapim’s product range, the Strong is developed for specific and heavy usage such as tandem, e-bikes or heavy load use. In case of large hub holes, the Strong is the recommended choice...

wheelbuildingparts.com

Spoke head washers as necessary (to compensate for oversize hub flange holes or thin flanges)

Sapim Spoke Head Washer

Spoke washers help adjusting bending better to the hub. This washer adds additional reinforcement at the neck of the spoke.

wheelbuildingparts.com

 

[Chalo]

And when the tire compresses the pressure in the tire increases everywhere .

No! This is a misconception. Do the math yourself; calculate the total volume of the tire and the total volume of the section that's compressed, generously assuming you bottom the rim on the ground and you do it on a purely flat surface. It's a very tiny percentage, diminished further by the fact that those assumptions are not true and by the fact that the tire is elastic and will expand in response to any internal compression.

Tire pressure doesn't vary significantly in response to dynamic loads. You can write that out of any realistic analysis.

 

[ebike4healthandfitness]

Here are two more links to add to information I already posted in post #24 ---> A seller told me the Ryde Andra 40 is not a suitable rim for a 1000w hub motor. Is that true?

Debunking Wheel Stiffness - Slowtwitch News

We take a close look at the concept of wheel stiffness. What does it mean? How does it affect your performance? Are all wheels created equal? For more myth-busting, read on.

www.slowtwitch.com

"More spokes and thicker spokes make a wheel stiffer both laterally and radially."

And here was the answer the author of the slow twitch article got when he asked several different manufacturers about the aerodynamic cost of adding 4 spokes to rear wheel:

"All replied with the same answer: The aerodynamic cost is minimal. The weight penalty is minimal. You do gain a little bit of radial stiffness – which could be seen as ride harshness"

Do you get that? All the manufacturers he asked actually volunteered the information about increased spoke count increasing radial stiffness.

Great wheel test – Part 3 – Stiffness | Roues Artisanales

"The spokes also play a role: their number, crossing pattern, tension and spoke stiffness (material, cross section) all have an influence on overall vertical stiffness of the wheel."

 

[ebike4healthandfitness]

No! This is a misconception. Do the math yourself; calculate the total volume of the tire and the total volume of the section that's compressed, generously assuming you bottom the rim on the ground and you do it on a purely flat surface. It's a very tiny percentage

It is not a very tiny percentage.

 

[Chalo]

It is not a very tiny percentage.

Use a pressure gauge to compare the same inflated tire loaded with axle weight and unloaded. Use as much weight as you like. The difference is negligible.

 

[ebike4healthandfitness]

Use a pressure gauge to compare the same inflated tire loaded with axle weight and unloaded. Use as much weight as you like. The difference is negligible.

You did not ask me to measure pressure (which no doubt involves a massive amount of force when using a realistically inflated tire and at the same time is most likely going to be coupled to a pinch flat). You asked me to measure change in volume (see below):

Do the math yourself; calculate the total volume of the tire and the total volume of the section that's compressed, generously assuming you bottom the rim on the ground and you do it on a purely flat surface. It's a very tiny percentage

And I'm saying the change in volume is not a very tiny percentage as you claim. Apparently you agree with me on that because you now have moved the goal post to something different which I think is going to cause a flat tire.

But why are we still arguing about all this stuff when my assertion that increasing spoke count does increase radial stiffness is already 100% proven true--> A seller told me the Ryde Andra 40 is not a suitable rim for a 1000w hub motor. Is that true?

This argument over whether or not increasing spoke count increases radial stiffness we have been having in thread is done. I was right and you were wrong. And why were you wrong? It's because you kept on basing your entire theory on a poorly done simulation while ignoring reality over and over again.

 

[Chalo]

You understand the relationship between volume and pressure in a fixed amount of gas, yes? If you did, you'd know that any significant change in volume would be reflected as a proportional change in pressure.

Tire volume doesn't change significantly when the tire is flexed under static or dynamic load. You can verify this in a number of ways.

Are you trolling?

 

[ebike4healthandfitness]

You understand the relationship between volume and pressure in a fixed amount of gas, yes?

Yes, obviously. It's called Boyle's Law.

And you asked me to calculate the volume change of a inflated tire vs. one that is loaded to the point where the rim is bottomed out on a purely flat surface:

Do the math yourself; calculate the total volume of the tire and the total volume of the section that's compressed, generously assuming you bottom the rim on the ground and you do it on a purely flat surface. It's a very tiny percentage

And here what a bottomed out rim would look like from a cross-section:



And here is what a bottomed out rim would look like longitudinally:



That is so obviously definitely not going to be a very tiny change in percentage.

 

[Chalo]

Remember the pressure is still there, so the shape you project won't be correct. Pressure will hold it wider open. And the casing will stretch.

You can keep wasting my time, but I'm not going to let you defecate misinformation all over this thread without being corrected. Go find one that doesn't have useful information in it and knock yourself out. Stink up the Sur-Ron thread with my blessing.

 

[ebike4healthandfitness]

Remember the pressure is still there, so the shape you project won't be correct. Pressure will hold it wider open.

Pressure is not going to hold it open because you specified a load strong enough to overcome the pressure such that the rim is bottomed out on a flat surface.

 

[Chalo]

Pressure is not going to hold it open because you specified a load strong enough to overcome the pressure such that the rim is bottomed out on a flat surface.

Go mess with another thread. I'm not letting your BS slide here.

 

[ebike4healthandfitness]

I'm not going to let you defecate misinformation all over this thread without being corrected.

Actually that would be you Chalo linking a very poorly done simulation that resulted in this rim deflection:





And then basing your entire theory on radial stiffness on it (which I was forced to use real world data to correct when all that was needed to understand was common sense and common bicycle knowledge that has been around for decades). Seriously Chalo bicycle wheels aren't made of cheese like this simulation makes it out to be.

 

[neptronix]

hey ebike4healthandfitness, do you think any of this is benefitting the original poster at this point?

 

[ebike4healthandfitness]

hey ebike4help and fitness, do you think any of this is benefitting the original poster at this point?

I certainly am. Chalo is not.

Maybe one day Chalo will be able to grasp basic concepts like this super obvious spoke issue or the fact that a tire doesn't have constant volume but rather only constant surface area.

I am trying not to be smug but every battle I have with Chalo ends with me always winning. I'm 53-0 in arguments against Chalo.

 

[neptronix]

 

[Gruesome]

I think a good half of the posts could be deleted from this thread, and not only would nothing be lost, but clarity would be improved.

 

[99t4]

hey ebike4healthandfitness, do you think any of this is benefitting the original poster at this point?

I certainly am. Chalo is not.

How about we rethink this.

OP Original question: "A seller told me the Ryde Andra 40 is not a suitable rim for a 1000w hub motor. Is that true?"

How do your numerous sidetrack posts battling Chalo just so you can rack up your 54th straight win () help answer the OP's question?

 

[ebike4healthandfitness]

How about we rethink this.

OP Original question: "A seller told me the Ryde Andra 40 is not a suitable rim for a 1000w hub motor. Is that true?"

I already told the OP in another thread he made about getting a rim for his 1000w hub motor that the Ryde Andra 40 is considered by many to be the strongest rim for 26". (I also made reference to the Ryde Andra 29 as being stronger but that is only available in 29" not 26")

The OP then reached out to me via PM about finding a place where could find the 26" Ryde Andra 40 and I helped him find a retailer with affordable shipping to the United States.

So yeah. He already knows I approve of the rim for his 1000w hub motor because I am the one who recommended it to him and located a seller for him to buy the rim I suggested.

 

[ebike4healthandfitness]

How do your numerous sidetrack posts battling Chalo just so you can rack up your 54th straight win () help answer the OP's question?

Chalo should have accepted my correction of his false statement and just moved on. This especially as I quickly provided links to prove what I said was true. I mean seriously not only is increasing spoke count a means of increasing radially stiffness but increasing spoke thickness is as well. This has been know for many decades as is even found on page 37 of Jobst Brandt's book the Bicycle wheel 3rd edition where he actually states that radially stiffness "is primarily influenced by the number and thickness of spokes" (see attachment). This is the opposite of the information that Chalo provided which is that only the rim provides radial stiffness.

 

[Papa]

I'll be brief... then permanently disappear from this volatile thread. Ropes for spokes?... Sure, why not?

 

[99t4]

The OP then reached out to me via PM about finding a place where could find the 26" Ryde Andra 40 and I helped him find a retailer with affordable shipping to the United States.

Please redirect such PMs back to the public forum. Helps us increase, maintain, retain our "institutional learning" component of our ES forum. Potentially helpful ebike information kept inside PMs remains hidden.

 

[neptronix]

Ah so that's why OP abandoned their thread.
This person's ask for help got crowded with bickering so they went private.

Let's not do that again!