Are Wider Tyres More Stable?

[Sunder]

Hey everyone. Just asking some advice before I spend even more money (done a fair bit of that lately).

Very quick background, my bike is now faster than I need or want it to be - and the tyres especially really don't feel stable at 50km/h+. Every time I go over a crack or a bump, it feels like the rear end is "floating" for a couple tenths of a second. No accidents yet, and I don't know if it's in my head, but I don't want to risk it. I currently have Continental Four Seasons on my bike - 700c x 28mm.

Would switching to a quality 44mm or even a 47mm make the bike more stable? I've heard that at high speed wide tyres can can cause bike shimmy.

Also, will knobbly tyres be more stable than slick style tyres?

I was chasing speed before, which is why I chose a 28 slick tyre - but with the current motor, controller and battery combo, I feel I can sacrifice a few km/h for better ride comfort and stability.

 

[Sunder]

Not one to reply to my own posts before anyone else replies, but I've just spent the last hour and a half reading up on tyre stability, pressures, treads, etc.

There seems to be almost no consensus on anything! Or if there is, there's still a thousand caveats. Like, mountain bike tyres are designed wider and knobblier for better stability, but sacrifice cornering stability at high speeds...

Probably won't get much consensus here either, but as we're much more specific with heavier, faster bikes here, I'd still trust anecdotes here more than studies done on standard bikes and riders.

Any comments would be appreciated at this point.

 

[DAND214]

Hi Sunder,
I don't know about being more stable but I do like how it rides. Less following a crack or grooves in the road. Knobbies are better off road for traction and cornering in dirt but not on paved roads. Narrow tires are better for less friction and less drag. fat tires do take a little more power than the skinny ones.

if you do go fatter/taller, you will also see an increase in speed if your setup has the extra power to do it. My wifes ride is a 700c setup and the fatter tire helps the ride and did increase the speed a little. My bikes are all 26" and are mostly 2.35 or 2.4 tires, love the ride and the security it gives me about the ruts and grooves in the pavement.

So Yes I do think they do help.

Dan

 

[edcastrovalley]

I would go with the bigger tire, sorry, tyre. I've had good luck with Schwalbe Big Apples and Maxxis Hookworm tyres. They work great at 50km/h+ but they're closer to 60mm wide. They barely fit my frame. Schwalbe calls theirs a "suspension tyre" and they do help out a lot on bikes with no suspension.

 

[erik_m]

(post deleted)

 

[Sunder]

Thanks for the feedback guys.

My rim is 19mm, so 47mm is the biggest that will fit on my rim (according to Sheldon Brown - who said he is admittedly conservative).

However, I don't know what my forks will fit.

My LBS doesn't have Hookworms or Big apple.

Any suggestions from this list:

http://www.99bikes.com.au/parts-components?cat=655

Thanks again for the opinions/advice.

 

[amberwolf]

Every time I go over a crack or a bump, it feels like the rear end is "floating" for a couple tenths of a second.

Do you have suspension? If so, maybe you just need to tune it for your speed/load.

If not, maybe you need suspension, or to change where your load is on the bike, so it reacts differently.


Sometimes, though, fatter tires at lower pressure work to fix this sort of thing.

 

[markz]

For stability a wider fatter tire is where its at.
I have ridden both a 700C and a 26" 2.3 tire, when I go hands free, its harder on the 700C, but easier on the 26" 2.3 tire.
Going electric, wider and fatter the better because then the bumps are not as noticable.

I was just doing research myself, thinking to myself I should get on the band wagon on this new fatty tire. They seem all the rage.
As far as I am concerned, my bike could probably fit a 20" 3.0 tire, gets way more torque, however I am unsure as to the pedal arm length if it will hit the ground more easier.

I would say a thinner tire, is more unstable and a wider/thicker tire is more stable at speed.

Like the fellow who posted the picture of the street motorcycle wheels. Got to be a reason why they are so wide.

 

[wesnewell]

Yes, wider tires are more stable, and paired with wider rims they're even more stable. I ran 2.4" tires for a long time on 24mm rims. Since going to 32mm rims a couple of years ago I'd never go back to narrower rims. The wider rims with the same tires made a world of difference. Narrow tires and rims have no place in the ebike world. It's really a shame they still sell them with the motors.

 

[Sunder]

If not, maybe you need suspension, or to change where your load is on the bike, so it reacts differently.


Sometimes, though, fatter tires at lower pressure work to fix this sort of thing.

Talk to me about this... the effect seems more noticeable since i moved the battery from a centre rear rack bag, to a left pannier bag.

Didn't think it would make much of a difference. Weight of battery and controller is only 5kg.

Markz -apologies for not quoting you, on a phone... can you explain why you're thinking of going down wheel size? Is that purely torque or still stability?

 

[markz]

So most common rims are 23mm wide.
Is it possible to buy a 19" or 20" rim in the 30mm+ range?

 

[wesnewell]

So most common rims are 23mm wide.
Is it possible to buy a 19" or 20" rim in the 30mm+ range?

Yes. But it may be hard to find them.
http://www.weinmanntek.com/Products/DOWNHILL/DH39.htm
http://www.weinmanntek.com/Products/CHOPPER/DHL42.htm
http://www.weinmanntek.com/Products/CHOPPER/DHL65.htm
http://www.alexrims.com/product_detail.asp?sc=0&cat=22&pid=82

 

[Ade]

I run 26 x 4+ inch tires on 4 inch rims and they are just amazing. Much better on bumpy roads or winter conditions.

 

[Sunder]

Yes, wider tires are more stable, and paired with wider rims they're even more stable. I ran 2.4" tires for a long time on 24mm rims. Since going to 32mm rims a couple of years ago I'd never go back to narrower rims. The wider rims with the same tires made a world of difference. Narrow tires and rims have no place in the ebike world. It's really a shame they still sell them with the motors.

Interesting - I've also read that the closer the tyre width to the rim width, the better aerodynamic performance. So a 32mm tyre on a 28mm rim would be aerodynamically better than the same tyre on a 21mm rim.

I'm not really in a position to rebuild my wheels after such a short period, but definitely will keep that in mind next time I am building an eBike.

 

[dogman dan]

My gut instinct would be to put as fat a tire as the frame allows. Screw what the rim width is. Skinny tires + racks and cargo seems to me like a bummer.

Skinny tires on a light bike, when I weighed 115 was great. Now that I look like Homer Simpson, I like a beach cruiser tire. You might not find anything like that for 700c, but surely you can find a 29er tire that's not a skinny slick. Just something with a bit of street tread, not knobby.

If they will fit, the maxis overdrive 1.75? That's still a narrow tire, but not "skinny" like a thin slick.

But that floaty feeling, I don't think it's primary cause is tire. Something is out of balance. Are you riding with drop bars? Or upright in the saddle? Floating the front tire is more typical for ebikes with rear hubmotors. Not the back tire.

Picture of your bike?

 

[Sunder]

But that floaty feeling, I don't think it's primary cause is tire. Something is out of balance. Are you riding with drop bars? Or upright in the saddle? Floating the front tire is more typical for ebikes with rear hubmotors. Not the back tire.

Picture of your bike?

It's a flat bar upright hybrid, definitely no drops.

Not sure if floaty, or twitchy is the right word... It just doesn't feel like the rear is keeping perfectly straight after hitting a bump. It can be a small as an expansion joint in the road.

It's midnight here in Sydney, but I can take some photos after work tomorrow and put them up.

Thanks for taking and interest and helping me diagnose.

 

[friendly1uk]

If a tramline is an inch wide, some tyres will fall in while others won't.
If a tyre is 2" deep, an imperfection 1.5" high won't pinch the tyre. Even if the tyre was particularly soft.
If a curb stone transitions from pavement to sidewalk in the space of an inch, an inch wide tyre would be off the ground for a moment, and just glanced away.

I read that a wider tyre actually rolled better. Seems odd. Yet side by side I coast downhill while sports cyclists are pedaling to do the same speed. I guess there entire weight is being bounced up and down which requires more energy than flexing my softer tyres.

I just did a quick bit of reading. Below 20mph the lower rolling resistance of wider tyres makes them faster than thinner tyres. Thinner one's are only faster above 20mph where aerodynamics tip the scale. Here we see aero rims with tyres of similar profile. Note though, that aero rims generally accept 24mm tyres not the ridiculously thin tyres of yesteryear.

I guess rolling resistance is not really a width thing, but more about the sidewall. The sidewall needs deforming, while the center just needs displacing. It's not very clear at a glance.

 

[melodious]

So most common rims are 23mm wide.
Is it possible to buy a 19" or 20" rim in the 30mm+ range?

Yes. But it may be hard to find them.
http://www.weinmanntek.com/Products/DOWNHILL/DH39.htm
http://www.weinmanntek.com/Products/CHOPPER/DHL42.htm
http://www.weinmanntek.com/Products/CHOPPER/DHL65.htm
http://www.alexrims.com/product_detail.asp?sc=0&cat=22&pid=82

Someone at Alexrims.com should upgrade their specs info to account for # of spoke holes. I think I'll contact them about it. I won't even charge then a consulting fee. :lol: Granted, most rims are the 32h variety, but can you imagine how much business they lost only because folks didn't know that info.

 

[amberwolf]

It just doesn't feel like the rear is keeping perfectly straight after hitting a bump.

the effect seems more noticeable since i moved the battery from a centre rear rack bag, to a left pannier bag.

Didn't think it would make much of a difference. Weight of battery and controller is only 5kg.

Based on those two things, I'd say that the offcenter load is pulling the bike to one side when you hit the bump--if the tires are stiff, at high pressure, it's probably worse than if you lower the pressure and/or use softer tires.

That's where the fatter tires at lower pressure come in, becuase they can deform around bumps easier without being slammed upward over them, or to the side if the load on the bike isn't even.


Remember inertia: wherever there is more mass on the bike that isn't centered over the point being pushed up or pulled down, it will take it more time to begin to move. Once it starts moving, it will take it more time to stop moving.

If it were at the center pivot point of the bike (usually where the rider is) then it works out best, but when it's off to one side, the bike may pull to that side, when it's off the front or rear beyond the axle it may cause the bike to tip more towards that end.

Between the axles, along the centerline of the bike, is the better box of area to stick things you don't want to cause uneven behavior.

If you have two identical loads they can be put at the sides, but I'd still put them between the axles (either in front of the rear or behind the front), and as low as you can get them.

The lower the load is to the ground, the closer to the pivot point of the pendulum-effect for side-to-side movement, and the less it's mass affects your ability to counter it, and the less it affects the "feel" of the bike.

The closer the load is to your own center-of-mass height, the more it affects the handling, unless you are wearing it. If you're wearing it you can shift it's weight around with yours, and the now-lighter bike's mass is below yours and easier to shift around. If the bike is wearing it, you can't shift it without shifting the whole bike, and it's harder to shift around the higher up it is, and the more it's off-centerness affects handling.

Do it long enough and you'll get used to it so it won't matter, though. Look at my DayGlo Avenger thread.

 

[arkmundi]

Yes, the more air cushion you have the better you're able to absorb the shocks and its those imperfections in your riding surface that is the source of instability. I put 2.5" Maxxis Hookworms on an Alexrims DX32 rim with Sapim spokes for my MAC/Trek Shift 3 build and am quite happy with the ride.

 

[friendly1uk]

My wheels are so stable, the baby jezus would of approved

Some weight in the wheel makes a lot of difference. It's all energy carried in the direction your heading.

Harder to accelerate,
Harder to stop,
Harder to change direction,
Whether you want to or not.

:|