Smaller wheels and hub motors

[Papa]

So basically a large attack surface for things like goathead thorns. That is just going to increase the chances for a flat tire.

Not my problem, so your statement does NOT apply to me.

 

[ebike4healthandfitness]

Not my problem, so your statement does NOT apply to me.

Flats aren't much a problem for guys like this either:

 

[Papa]

No bicycle tire except a few models of very heavy kenda tire come close to the amount of rubber depth a mid weight motorcycle tire has.

Probably true. I wouldn't know.

But I refuse to tack-on 8 to as high as 15 pounds of unsuspended dead weight to my wheels.
You and I have been down this road before, Chief, so I'm not inclined to repeat again.

 

[neptronix]

I've posted the test results in other threads; IE longest goathead i've seen in my area (11mm) versus about a dozen tires if you wanna reference.

I'm not saying you have to do anything, i'm saying there's upsides to 5 pound tires for some scenarios ( comfort, flat protection, or very high power/speed ).

I swear it's not a totally dumb idea

 

[bengxe]

For appeasing hub motors, stowing in cars, shipping in airplanes, yes small wheels are best.

For riding, the bigger the better.

What is your bike for?

For riding slowly in a straight line, bigger is more efficient. But wheel rigidity matters and is dramatically affected by rim diameter.

Not true.

Within limitations, trail can be altered without swapping or modifying the fork. And..., repositioning the front wheel slightly forward, typically improves handling.

Care to elaborate? Front wheel diameter is the only other relevant factor, and I'm not interested in changing that either. Moving the wheel forward "typically improves handling" when you're standing up and going down a mountain, not when you're seated and on a flat road.

I never implied they were an authority. I'm merely pointing that Schwalbe's technical reasoning mirrors that of many performance tire manufacture's... and I concur e.

You implied they were an authority by mentioning their name, that's how that works.

 

[ebike4healthandfitness]

Trail isn't something you have control over without swapping forks, and it doesn't compensate for the front wheel being too far out in front. I would say bar height and stem length are both more important than the 3 you mentioned, but I have no idea what you meant by "tiller". I'm assuming grip angle means bar bend angles?

Not true.

Within limitations, trail can be altered without swapping or modifying the fork. And..., repositioning the front wheel slightly forward, typically improves handling.

Repositioning wheel forward on fork without changing offset of fork?

This is not possible, at least not in any manner that is safe.

 

[Chalo]

For riding slowly in a straight line, bigger is more efficient. But wheel rigidity matters and is dramatically affected by rim diameter.

For riding fast and efficiently, bigger is better. For ride quality, bigger is better. For handling qualities at speed, bigger is better. For bridging gaps and easing bumps, bigger is better. For traction, bigger is better. For tread wear, bigger is better.

Wheel rigidity is a function of many factors, and wheel diameter is only one of them. But it's the one that harms the most other properties you want in a wheel, when you go smaller.

 

[neptronix]

While i'm here..

Big fan of the 26" F / 24" R setup. Here's mine.
Look at that slack angle and crank forwardness.. helped by another 20mm of suspension up front over stock.

Super comfortable and handles high speeds a lot better than stock. It's basically a crank forward downhill bike now.

 

[Papa]

Repositioning wheel forward on fork without changing offset of fork?

This is not possible, at least not in any manner that is safe.

Did not state or even imply that.

You apparently need optical assistance..... or suffer from Aphasia.

 

[Papa]

You implied they were an authority by mentioning their name, that's how that works.

Have it your way then (I could give ashit less).... yup,... Schwalbe IS in fact an authority on bicycle and e-bicycle tires.

 

[ebike4healthandfitness]

Did not state or even imply that.

You apparently need optical assistance..... or suffer from Aphasia.

You did state that. At the bare minimum it is definitely implied because the only way a person can reduce the trail increase caused by the now slacker head tube angle is by positioning the wheel forward on the fork somehow. Normally moving the wheel forward on the fork is done by increasing fork offset but you say you can accomplish this same thing without swapping or modifying the fork.

Me and e-HP are both big fans of 24" rear, 26" front configurations. Another upside is that this creates a slacker fork angle, and gives you more of a crank forward positioning when pedaling, which is comfortable. You can also run a honker of a 24" rear tire if you wish.

22" will also accept 18" motorcycle tires ranging from 2.25" wide to ~5" wide.

Depending on the bike, the slacker head angle isn't always an upside.

Slack headtube angles typically require an appropriate amount of positive trail. But there's three other attributes that needs careful consideration when fooling with steering geometry ..... and that's tiller, handlebar width and grip angle.

Trail isn't something you have control over without swapping forks, and it doesn't compensate for the front wheel being too far out in front. I would say bar height and stem length are both more important than the 3 you mentioned, but I have no idea what you meant by "tiller". I'm assuming grip angle means bar bend angles?

Not true.

Within limitations, trail can be altered without swapping or modifying the fork. And..., repositioning the front wheel slightly forward, typically improves handling.

 

[bengxe]

A slacker head angle moves the front wheel forward, that's what I was referring to. I'm still not sure what Papa was getting at about fixing the trail.

 

[Chalo]

A slacker head angle moves the front wheel forward, that's what I was referring to. I'm still not sure what Papa was getting at about fixing the trail.

Slacker head angle increases natural trail, which makes the steering floppy and unstable at low speeds if you use a fork with normal offset. Longer fork offset fixes that. However for higher than natural bicycle speeds, increased trail can help handling and stability. (Motorcycles often feature very slack head angles with bicycle-like fork offset.) For heavy front axle loads, decreased trail/greater fork offset makes the steering more manageable and lighter.

Trikes behave much better with a lot less trail than bicycles, so any given head angle should be (but usually isn't) paired with a fork that has much more offset than a bicycle would use.

 

[neptronix]

Wonder if OP is interested in this thread still

 

[bengxe]

Slacker head angle increases natural trail, which makes the steering floppy and unstable at low speeds if you use a fork with normal offset. Longer fork offset fixes that. However for higher than natural bicycle speeds, increased trail can help handling and stability. (Motorcycles often feature very slack head angles with bicycle-like fork offset.) For heavy front axle loads, decreased trail/greater fork offset makes the steering more manageable and lighter.

Trikes behave much better with a lot less trail than bicycles, so any given head angle should be (but usually isn't) paired with a fork that has much more offset than a bicycle would use.

My issue with the head angle change had nothing to do with the steering feel, I was referring to how far back in the wheelbase my center of gravity ended up with me seated. Going to the smaller rear wheel forced me to tuck my chest down to the bars in corners far too often for my liking. Papa pulled the trail idea out of left field, but this thread was thoroughly derailed long before that.

 

[Papa]

You did state that. At the bare minimum it is definitely implied......

Nope... read it again..
Two separate sentences.
Two separate statements,

"Within limitations, trail can be altered without swapping or modifying the fork.

And..., repositioning the front wheel slightly forward, typically improves handling."

 

[ebike4healthandfitness]

Nope... read it again..
Two separate sentences.
Two separate statements,

"Within limitations, trail can be altered without swapping or modifying the fork.

And..., repositioning the front wheel slightly forward, typically improves handling."

Papa,

Explain how you are going to normalize the trail (i.e. the trail should be the same as it was before).

Both bengxe and I have each asked you a question (bengxe in post #30 and me in post #31) after you wrote that above in post #21.

Yet you aren't answering.

Clarify what you mean.

 

[bengxe]

I guess I did use a question mark, but I wouldn't say I was expecting an answer. If you're interested in learning about trail, there are better sources than this guy.

Fork offset, head angle, trail

The only variable I changed was the head angle, but a change in fork offset or front wheel diameter will affect it as well. This means that you can vary the front tire size to adjust the trail slightly, bigger tire = more trail. My experience on DH bikes taught me that lower offset and more trail = better. Turning the crowns around backwards to drop the offset was one of the few changes I made to that bike that made it both more stable and easier to turn. But for e-bikes on pavement I'm still not sure. That article I linked is from 2017 and the lowest offsets mentioned were 40-42mm, and my 2023 Pike has 37mm of offset, so I guess offsets are still trending down?

 

[G8trwood]

on the small wheel topic. Took my brother to a light offroad park yesterday as he wanted to meet up with a group to look at their mobility gear and chat. Most were handcycle tads, with and without motors. One unique trike went by (he didn’t stop), tadpole fat trike, no human power visible, and what looked to be a hub motor in a 12” minibike rim. Front tires looked like 20’s. It moved down the course pretty efficiently. So of course I got back home and ran 50 simulations in the motor sim for 16” bike wheels……

Couldn’t find the guy later to get the specifics, so of course my brother goes,I want that, lol.

 

[ebike4healthandfitness]

I guess I did use a question mark, but I wouldn't say I was expecting an answer. If you're interested in learning about trail, there are better sources than this guy.

He just wanted to cause trouble and waste our time in this thread.

 

[neptronix]

Here's my MTB with a 24" rear and 26" front.

The fork angle is as such that it's more stable at high speed than stock. It could tolerate a 22" rear wheel and not get excessive, but start handling poorly at lower speeds ( who cares when you have a 35-40mph capable setup, the bike doesn't go below 10mph for very long. )



The only reason i don't use a 22" rear wheel is aesthetics. The suspension seatpost takes >=80% of the bump energy out of the rear wheel, so going with a smaller wheel is not a serious negative for comfort.

 

[neptronix]

Differences when climbing a hill when you go with a smaller wheel are significant:; this 4% increase in efficiency means the difference between the motor overheating and not.

 

[MxusMick]

I have 2 ebikes with 20" rear DD hubs and 26" front wheel on full suspension frames, the pedal gets pretty low but the torque improves from a 26" on a steep hill.substantialy, and surely keeps the heat down. The ride is EWOK chopper style with BMX bars.

 

[MylarStar]

I keep seeing lots of BMX companies offering 18” rims. I was thinking about swapping out my rear 20” rim that already has a motorcycle tire on it and going down to the 18” if I can lace it to my hub motor without having to do a radial pattern because it’s an off-road bike. I would definitely like to have the extra torque I’d get and I’m guessing 18” rim in bike terms means 14” tire in motorcycle terms. There would probably be something usable that’s not too huge.

 

[MxusMick]

The experiment is the fun! I salvaged a set of Razor mini edirtbikes, they are probably 12" knobbies, bet they would work well with a belt drive. My 3IY ebikes look similar to Neptronix with full suspension and all use a bigger front wheel. Maybe we will all be flying around in DIY DRONES pretty soon.