the 700c slim tyre riders thread

[GVD]

@onewheeldave

Today’s rides involved both the 700c x40 and the KH 29-er, so I got a chance to compare the two.

I’ve also been considering building a slim 700c from scratch and have it as a dedicated lightweight super-elegant uni.

I really don’t need a ‘bomb-proof’ hub, or a ‘super-wide’ rim, or cranks that can survive 6 foot drops- all those things merely add weight, cost and, often, complexity.

And while it’s good that the extreme equipment is available for the extreme riders, surely I’m right in thinking that many, possible even most, unicycle riders, just like to ride around, or are into distance, or fitness etc, etc.

Great post - thanks for the comparison. I’m one of those that has no interest in anything off-road and doesn’t need an overbuilt uni. I come from a bicycle racing background where mountain bikes are mountain bikes and road bikes are road bikes. In unicycling I’m finding that there really isn’t much differentiation!

I’m thinking along the same lines as you. I have been doing some research today and am ordering a custom wheel from UDC. I’m thinking of the 700c Sun 36 hole rim coupled with a KH hub. The Sun rim is pretty narrow which will allow pretty much any road bicycle tire.

I’m then thinking of mounting Continental Gatorskins which are some of the most robust road tires out there. Many bicycle racers use them as their winter training tire on the bike. They never flat and are pretty good at a range of pressures and last forever. They come in 23mm or 25mm.

I’ll give a report once the wheel arrives.

[joemarshall]

@onewheeldave

I really don’t need a ‘bomb-proof’ hub, or a ‘super-wide’ rim, or cranks that can survive 6 foot drops- all those things merely add weight, cost and, often, complexity.

And while it’s good that the extreme equipment is available for the extreme riders, surely I’m right in thinking that many, possible even most, unicycle riders, just like to ride around, or are into distance, or fitness etc, etc.

The newer isis hubs aren’t much different in weight to the old suzue ones - and you can get lightweight aluminium cranks for them. There isn’t much weight penalty. They also have less hassles with aluminium cranks deforming, which should increase reliability compared to square taper. 2 wheeled Road bikes often come with isis cranks now, so it can’t be that bad from a weight point of view.

The lack of narrow rims is a fair point - although they’re a standard bike part, so it’s easy to get one. I don’t think the wide rims are a hardcore equipment thing though - the fat road tyres are much more suited for beginners than a narrow one.

Joe

[onewheeldave]

@joemarshall

The newer isis hubs aren’t much different in weight to the old suzue ones - and you can get lightweight aluminium cranks for them. There isn’t much weight penalty. They also have less hassles with aluminium cranks deforming, which should increase reliability compared to square taper. 2 wheeled Road bikes often come with isis cranks now, so it can’t be that bad from a weight point of view.

The lack of narrow rims is a fair point - although they’re a standard bike part, so it’s easy to get one. I don’t think the wide rims are a hardcore equipment thing though - the fat road tyres are much more suited for beginners than a narrow one.

Joe

I guess the thing is, I like square taper hubs/cranks- I .like the fact that, after plenty of practice, I’m good at changing them- they’re all the same/stanardised (unlike the variety of splined setups), they’re cheap etc, etc.

In terms of their ‘weakness’- they’ve never let me done.

Just as important, in the old days, it was easy to switch stuff from one unicycle to another- cranks, seat-posts etc, etc.

That’s no longer possible now I’ve got my old style nimbuses and the KH- you can’t even share a saddle, never mind cranks.

The other effect is that ordering stuff from uni.com now requires a high degree of double/triple-checking to ensure the parts you’re getting are actually going to fit.

Plus, each variation in kit requires a set of new tools.

Now, I’m not saying the new stuff is bad- just having a moan about the fact that the perfectly good old stuff, which many would still use/buy if it was available, is no longer sold.

[Mikefule]

Well, this thread inspired me to get the Bacon Slicer out. First after-work evening ride of the season - the first Monday after the clocks went forward.

23mm slick tyre on a 700c rim, and with 125mm cranks. Tyre pumped to just over 120 psi. AS I prepare to mount in a parking space near the river, a flight of pure white geese takes off noisily and passes overhead in formation.

The first few hundred metres were wobbly, and when I tried to adjust my foot on the pinned pedal, it felt glued in place. Then I found a long flat straight and started to spin, plucked up the courage to ride over the cattle grid and I was away - down a side track, then along a baked mud bridle path with high hawthorn hedges to both sides, and trees growing over to make a tunnel.

A quarter of a mile down there, I met a man with the most magnificent boxer dog I’ve ever seen. It stood staring at me, planted four square and ready for anything. I broke the ice by shouting to the man, “Is he usually OK with unicycles?” I’m not sure he understood the irony, but he replied in kind and the dog relaxed. as I rode past, it looked up at me with those big sorrowful brown eyes, probably pitying me for the loss of my other wheel.

On to the river bank, and a baked mud rut between rough grass. Doing well here, to say that it used to be my ambition to ride this on the 26 x 1.75 on 150s. The skinny wheel takes 100% concentration on this stuff, and I’m having a whale of a time, then a mile into the ride I have a concentration lapse and UPD. I take the opportunity to take off my sweatshirt and put it in my bag.

More of the same, and then an area of broken ground, rough ballast and some of the potholes filled with hardcore. Yippee! I’m a hardcore rider.

Small stones usually ping out from under the hard skinny tyre, making the spokes resonate - but one decides to make a defiant stand and suddenly I am airborne, landing heavily and skinning my knee.

Out onto the footpath at the side of the main road, and for half a mile or so, not one driver hoots, gesticulates, flashes his lights or shouts inane comments. What is the country coming to?

Back onto a bridle path and a couple of miles back to the car. I divert to do the tunnel of trees again; the hawthorn is sprouting the fresh green leaves of spring. A sooty-dark fox runs ahead of me for a minute or two.

Out of the tunnel and I meet a lady walking her labrador puppy which bounds up to me causing me to dismount and make a fuss of it. It’s been swimming and is glad to have someone to cover with muddy water.

Back over the cattle grid and a quick sprint to overtake a wobble-bottomed jogger then I am cruising back towards the car to the sound of sheep baaing in the twilight.

I’d forgotten how much fun the Bacon Slicer can be.

[saskatchewanian]

Mike nice little right up.

Was there deliberate mistakes? One really pops out at me.

I am going home next weekend and will pick up my skinny wheel MUniing is really sloppy and wet right now anyways, and will be for the next month or two while things are thawing unless it freezes hard again. Hopefully the streets will be mostly clear of snow by next sunday.

Looking forward to zipping around town on a skinny wheel again.

[Mikefule]

@saskatchewanian

Mike nice little right up.

Was there deliberate mistakes? One really pops out at me.

Thanks.

No deliberate mistakes there. The two obvious candidates for accidental mistakes are:

Have I mixed up hawthorn and blakthorn? One of them blossoms before the leaves bud; the other vice versa and I may have got it wrong.

The fox really was sooty-dark.

Many years ago, on the Pashley 26, I saw the reddest red fox imaginable, leaping up from a cornfield in a failed attempt to catch a grouse it had startled.

The fox I saw today was sooty/grubby grey/brown. Many urban foxes are like that these days. This whole ride was never more than a mile from a built up area, and I think most of our foxes survive on thrown away takeaways. The urban foxes are less red ‘n’ proud than their urban counterparts.

[Rowan]

@Mikefule

The urban foxes are less red ‘n’ proud than their urban counterparts.

Another deliberate mistake?
Surely you mean their rural or suburban counterparts.

I’ve always been fond of the narrow tire fast unicycle idea, but after riding a 36" for a while the 28" mostly feels like a toy unicycle, even with a gear (a big wheeled toy unicycle). The stability and inertia of all that rubber has it’s own value when you are cruising along at high speed. There is the lost efficiency of hill climbing with a big wheel, but added security on the downhills of some bump absorbing. I can’t seem to make up my mind what would be best- a 700x23c geared unicycle or 36", but I’m tending towards the 36" idea. Can’t wait to try someone elses one, that is bound to happen well before I can afford one.

[Mikefule]

@Rowan

Another deliberate mistake?
Surely you mean their rural or suburban counterparts.

I’ve always been fond of the narrow tire fast unicycle idea, but after riding a 36" for a while the 28" mostly feels like a toy unicycle, even with a gear (a big wheeled toy unicycle). The stability and inertia of all that rubber has it’s own value when you are cruising along at high speed. There is the lost efficiency of hill climbing with a big wheel, but added security on the downhills of some bump absorbing. I can’t seem to make up my mind what would be best- a 700x23c geared unicycle or 36", but I’m tending towards the 36" idea. Can’t wait to try someone elses one, that is bound to happen well before I can afford one.

Yes, I posted it very late at night. Urban foxers are less red and proud than their rural counterparts.

Have no doubt whatsoever that there is no practical advantage to a skinny tyre over the duration of a whole ride. It accelerates and decelerates faster, but is far more sensitive to the vagaries of the surface, is harder work, and has a lower top speed and average speed. A 29er would be more practical, more versatile and faster.

In the same way, you could always win a fencing match if you used a shotgun instead of a foil.

[onewheeldave]

What do think of this-

http://www.unicycle.co.uk/shop/shopdisplayproduct.asp?catalogid=918

not a 700c (it’s a 26" rim with a tyre so small as to take it under the official size requiement for a 24" wheel for racing events), but has the narrow rim and super-narrow high psi tyre.

It weighs only 3.3 kg!

People say that it’s not a practical uni for anything but racing, however, it’s not that much different in terms of tyre/psi than what some of you are using on the roads in 700c.

[onewheeldave]

What do think of this-

http://www.unicycle.co.uk/shop/shopdisplayproduct.asp?catalogid=918

not a 700c (it’s a 26" rim with a tyre so small as to take it under the official size requiement for a 24" wheel for racing events), but has the narrow rim and super-narrow high psi tyre.

It weighs only 3.3 kg!

People say that it’s not a practical uni for anything but racing, however, it’s not that much different in terms of tyre/psi than what some of you are using on the roads in 700c.

[onewheeldave]

Here’s a question- probably very difficult to give a technical answer, but relevant to the issue of light tyre and hill climbing.

Given that hill climbing (on roads) is very much affected by tyre weight, so, on a 700c, presumably, the lighter the tyre the better (down to the point at which the tyre crosses the line and the high psi creates issues with minor road imperfections).

The effect is considerable not so much because the tyre has mass, it’s because it’s rotating mass.

So, how would a comparison go between similar tyres, but on a smaller wheel?

For example, a 1" 700c tyre vs. a 1" tyre on a 26" rim?

Presumably the physics would say that, in addition to the lower actual mass of the 26" tyre, the fact that it’s closer to the hub (smaller radius) would also need taking account of?

[rob.northcott]

@onewheeldave

but has the narrow rim and super-narrow high psi tyre.

That’s a wider tyre than Mike’s Bacon Slicer. Still, pretty skinny for a unicycle.

I’ve not ridden a really narrow-tyred unicycle, but the general feeling seems to be that it doesn’t really work (apart from being a fun challenge).

The reason road bikes use narrow tyres is primarily to get the (rotating) weight of the wheel down, which leads to a more responsive feel and faster acceleration. The common belief that it’s to reduce road drag is a misconception - in fact I’m pretty sure it’s been proven that a wider tyre at the same pressure has lower rolling resistance.

But on a unicycle, fatter tyres give a more forgiving ride, and that counteracts the inertia disadvantages of the heavier wheel - acceleration isn’t as important as stability on a unicycle. A unicycle that’s easier to ride and less likely to get tripped up by every bit of gravel can be ridden faster.

Perhaps a bigger lightweight wheel would be a good compromise for a unicycle - something like a 40" x 1", a bit like the old solid-tyred bigwheel cycles, but with a tyre more like a modern road bike. The extra diameter should help with inertia and stability, but the overall weight could probably be kept quite low for easier climbing.

Rob

[bungeejoe]

Harder to keep it straight …

@onewheeldave

Here’s a question- probably very difficult to give a technical answer, but relevant to the issue of light tyre and hill climbing.

Given that hill climbing (on roads) is very much affected by tyre weight, so, on a 700c, presumably, the lighter the tyre the better (down to the point at which the tyre crosses the line and the high psi creates issues with minor road imperfections).

The effect is considerable not so much because the tyre has mass, it’s because it’s rotating mass.

So, how would a comparison go between similar tyres, but on a smaller wheel?

For example, a 1" 700c tyre vs. a 1" tyre on a 26" rim?

Presumably the physics would say that, in addition to the lower actual mass of the 26" tyre, the fact that it’s closer to the hub (smaller radius) would also need taking account of?

My limited experience suggest that you forget about rotational weight in climbing. Also forget about any weight changes less than a couple of pounds. In climbing steep slopes the speed is slow. Fact, strength and technic are not replaceable.

Climbing on steep slopes (above 12%) on a slim hard tire requires good technic or the wheel will wobble left and right. The smaller the contact on the ground the more I need to maintain good technic at the sacrifice of strength to keep going straight.

[Mikefule]

@onewheeldave

What do think of this-

http://www.unicycle.co.uk/shop/shopdisplayproduct.asp?catalogid=918

not a 700c (it’s a 26" rim with a tyre so small as to take it under the official size requiement for a 24" wheel for racing events), but has the narrow rim and super-narrow high psi tyre.

It weighs only 3.3 kg!

People say that it’s not a practical uni for anything but racing, however, it’s not that much different in terms of tyre/psi than what some of you are using on the roads in 700c.

I drooled over that a few months ago, but couldn’t persuade myself that if offered much that I don’t already have in my existing fellet. I have a 24, 26 and 28 and the 28 with its skinny tyre is only 16% different from the racing model.

Nice uni, though, and if I had the money, I’d buy one. But I wouldn’t race it, I’d do cross country.

[onewheeldave]

@bungeejoe

My limited experience suggest that you forget about rotational weight in climbing. Also forget about any weight changes less than a couple of pounds. In climbing steep slopes the speed is slow. Fact, strength and technic are not replaceable.

My experience inclines to the opposite conclusion- that rotating mass of the tyre is possibly the most important factor in hill climbing.

My recent experience that the relatively heavy WTB Stout 2.3 29-er tyre @ 1100g is incredibly draining on the hills, while the Kenda Klaw 29x1.95 @ 760 g is far less so (as is the 700c x40 slim tyre).

(Bear in mind that I’m talking in the context of rides with a good proportion of steep and/or long hills- I think if hills are occasional or mild, then you won’t have problems even with a fat tyre)

I very much agree that, on steep hills, speed is slow, but I’d say that that is actually more good reason why a lighter tyre is preferable.

Because the reason really steep climbs are slow is that you tend to go up in a series of half wheel rotations, with a micro-pause at the top, before pushing down for the next half rev.

That means that, for each half-rev, the wheel is actually static for a period.

The physics of acceleration mean that it’s harder to start a mass rotatiing than it is to keep it going.

For that reason, every extra bit of mass on the tyre is going to add to the amount of energy needed to power it up a steep hill.

@bungeejoe

Climbing on steep slopes (above 12%) on a slim hard tire requires good technic or the wheel will wobble left and right. The smaller the contact on the ground the more I need to maintain good technic at the sacrifice of strength to keep going straight.

I’ve got limited expience on really skinny tyres, but, from riding a 700c with high psi, I’d say you’re right.

[onewheeldave]

@Mikefule

Nice uni, though, and if I had the money, I’d buy one. But I wouldn’t race it, I’d do cross country.

[Mikefule]

I think the benefit of a heavy soft tyre -vs- a light hard tyre varies with the nature of the climb. Momentum helps if you are rushing the hill; squidginess helps if you are “stomping” up an uneven surface; lightness helps if you are marching up a fairly smooth incline.

Technique is 90% of the battle.

[Ergolicious]

Mind as well post some pictures of my skinny tire unicycle

The seat is terrible, pretty much numbs your crotch after 2 minutes of riding…

[Rowan]

@Mikefule

I think the benefit of a heavy soft tyre -vs- a light hard tyre varies with the nature of the climb.

If only the cycle-path portion of roads were made smooth without bumps- the smooth tire would be ideal!

@Ergolicious

The seat is terrible, pretty much numbs your crotch after 2 minutes of riding…

KH seats, even the old ones are much better than Savage saddles and some other types that were previously common. If you ride long enough you get numb on any type of saddle almost- the longer you ride the more you get used to it. If you are numb in 2 mins you have not been practising long distance enough. If you think that seat is terrible, what is a good seat?

[saskatchewanian]

In my experience weight definitely make a difference when climbing. I even experimented with weights on the spokes so the setup would be the same except for the weight and my findings were that the skinny wheel with weight was harder to climb with but smoother on the descents.

I felt the hills way more with the weighted wheel.