Big Wheel vs. Geared Small for High-Speed; Performance

[lunicycle]

Originally Posted by magnustudios

That's a great article, Sam, cool to hear from a muni perspective. I hadn't seen that website before, but there's some good stuff.

heya thanks. I hadn't gone back and read that article since last September - my point of view hasn't changed much since then.

The feel of 24 GUni in high gear (virtual 36'er) can't really be replicated on the single speed 36. As Sam mentioned in the Total Gear Ratio thread the closest thing to riding high gear on a GUni is a bike e.g. riding an MTB in a gear that creates a similar load on your legs.

On a single speed 36'er there's a lot of spinning lightly and making use of that giant flywheel. It almost rolls itself along once you get it going.

Compared to the single speed 36'er there is minimal flywheel effect on the 24 GUni in high gear - there's a lot more pushing on the pedals, through the gearing, to keep buzzing along.

For road riding it would be hard to imagine a circumstance where a single speed 36'er wouldn't be a 'better' i.e. more efficient choice than a 24 GUni. Off road though it's a different equation.

There are a bunch of other differences that come into play when comparing a single speed 36'er to a 24 GUni. I guess rather than generalizing too much, which one has better performance etc depends more on the rider, terrain, situation etc.

Fwiw, since putting the hub into a 24" last September I pretty much haven't ridden the 29'er at all, and the 36'er not that much. Of course the 24 GUni is still a compromise, but for me it's just a lot more satisfying/fun to ride - that's my performance criteria

[corbin]

Originally Posted by scott ttocs

Hi Corbin,

Would you be willing to post times with the three unicycles?

I agree that minimizing seat time in a long ride would add to the comfort level.

Scott

Hey scott,
it is a leisurely ride, with lots of stops -- not a race. It takes all day...and I tend to ride "with the group". Except a few years ago when chuck and I raced through it on our geared 36's (this was not too long before RTL).

corbin

[jogi]

yesterday I rode with enaddi (Nadine) about 10Km in urban periphery.
she rode a 26" x 3" Gazza, Triton Schlumpf, 125mm cranks and I rode a 36" Schlumpf 150mm cranks.

- She was faster upphill when i had to shift down (Ok, that depends on the power, but if both have the same power its just a question of the grade of ascend) and
- she was much faster in speeding up - altough using only high gear! (she is trained to ride her fixed gear 1:1.75 29")
- I had more maximum speed but at all - in this surrounding of up and downs and traffic lights a 26" x 3" or 29" Schlumpf is faster and makes more fun than a 36" even with schlumpf - (mostly the gazza is no good choice for road but thats my offroad setup)

@michael
If you would ride 100 miles with Dave - I mean he rides 100 and you about 50 you would understand words like "fast" and "uphill" in his understanding

[magnustudios]

This discussion has been really informative. Thanks for all the feedback so far!

I swapped out my 36" inner tube for a 29" on my kh36 the other day. At first I really liked it, but it seems to wobble a lot more. It makes me want to ride with shorter cranks.

I can't say how much it's related, but I did a 30k ride on Friday and found my backpack swinging back and forth almost uncontrollably on many downhills, and on straight stretches if I was going at just the right speed, which seemed to be right in the middle of my comfortable range. I had a bit more weight than I normally carry, so maybe that's the problem more than the lighter wheel, but man, it sure freaks drivers out. Maybe it's just time to get a brake.

It got me thinking though, how does the amount of wobble compare between large heavy wheels and small light wheels? On a 24 in schlumpf high-gear you'd be pedaling the same cadence as someone on a 26 for a given speed, but I'd imagine the stabilization from the wheel would be much less.

Do people have trouble with this at all? Are backpack oscillations more extreme?

[saskatchewanian]

I can't comment on the geared 24 but when I go to a lighter wheel of any size i loose some smoothness. and yes you can get some of that smoothness back from going with shorter cranks, which translates into a faster setup. Bonus.


what helps with backpack oscillation is straps, lots of straps. You should be using the shoulder, chest, AND waist straps. If your backpack does not have them you can sew some webbing on and add clips. If setup right they will not interfere with the movement of your body and keep the backpack firmly planted on your back.

Next i also like having compression straps on the backpack so I can tighten up the load so it does not move within the pack.

[bungeejoe]

Originally Posted by magnustudios

I swapped out my 36" inner tube for a 29" on my kh36 the other day. At first I really liked it, but it seems to wobble a lot more. It makes me want to ride with shorter cranks.

n straight stretches if I was going at just the right speed, which seemed to be right in the middle of my comfortable range. I had a bit more weight than I normally carry, so maybe that's the problem more than the lighter wheel, but man, it sure freaks drivers out. Maybe it's just time to get a brake.

Can you pedal and maintain a straight tire track? Wobble can come from how we apply power to the pedals. When we push forward across the top of the stroke the force pushes the wheel into a wobbling tire track. Larger wheels are harder to track straight. It becomes really noticeable when riding a ordinary bike (penny farthing) up a hill.

[siafirede]

Originally Posted by magnustudios

This discussion has been really informative. Thanks for all the feedback so far!

I swapped out my 36" inner tube for a 29" on my kh36 the other day. At first I really liked it, but it seems to wobble a lot more. It makes me want to ride with shorter cranks.

I can't say how much it's related, but I did a 30k ride on Friday and found my backpack swinging back and forth almost uncontrollably on many downhills, and on straight stretches if I was going at just the right speed, which seemed to be right in the middle of my comfortable range. I had a bit more weight than I normally carry, so maybe that's the problem more than the lighter wheel, but man, it sure freaks drivers out. Maybe it's just time to get a brake.

It got me thinking though, how does the amount of wobble compare between large heavy wheels and small light wheels? On a 24 in schlumpf high-gear you'd be pedaling the same cadence as someone on a 26 for a given speed, but I'd imagine the stabilization from the wheel would be much less.

Do people have trouble with this at all? Are backpack oscillations more extreme?

For what its worth, a geared 29er feels more squirrely than a geared 36er, probably due to the wheel size/weight.

[saskatchewanian]

Thought I would dig us this thread since this is sort of big wheel vs small geared wheel related

Went for a couple back to back rides today with a G24 and my 32" just to compare how they compared.

Critical stats:

24" GUni
24x2.25 tire
47mm rim
125mm cranks
3.7:1 gain ratio (in high gear)
7.20 kg

32"
32x1.75 tire
28mm rim
114mm cranks
3.5:1 gain ratio
5.89 kg

First I took the GUni out for a spin, went down the highway, took a gravel road then went back through town. The thing felt a little sluggish getting going up the first hill but I soon got a good pace going. The wheel was pulling a tiny bit because of road crown but not too bad.

Got onto the grave and was doing great until I hit some washboard and ended up doing a running UPD. Jumped back on and kept on going. Once I got into town I had to do the "pothole slalom" Our streets are more pothole than pavement in the spring and this year is no exception. Going uphill dodging the potholes the GUni was excellent, nice fast and nimble. On the downhill pothole dodging though you could feel the slop in the gears, which didn't really affect anything but gives sort of a disconnected feel.

Before getting back to the house I hit a patch of mud which really slows down the GUni but didn't throw me this time. Got back to the house and checked the time. The loop took me 21 minutes.



Brought out the 32 and mounted up. First thing I felt going to the light 32 from the GUni is how light and "refined" it feels. No slop at all and very responsive. I should mention that I only have about 3km of riding on this wheel so far.

I had no trouble getting it up to speed climbing the first hill and was cruising right along. I could not feel the road crown at all on this unicycle but was blown a bit more by the wind. Though the gain ratio is not all that much different than the G42 I really felt that I should loose a bit of length in the cranks (which I did not feel on the G24).

I wasn't sure how the skinny tire would handle the gravel but it just cruised right along. I guess the large diameter made up for the skinny width of the tire. Hit the washboard section and had no problems, the wheel seemed to flow through it better than the 24 which more bounced along.

Got to town and the pothole slalom course. I was expecting the light wheel to be really nice and flickable, making it really easy to do all the sharp little turns while keeping the speed up, It didn't. I felt comparatively unstable navigating between the holes and felt much more precarious being higher up than the GUni. Something I never felt with a big heavy 36.

The big wheel cut through the mud patch with barely a notice and when I got home checked the time, 19 minutes.


So no good hard evidence for anything there but I would have to say that I preferred riding the 32 over the G24 on everything except in town dodging potholes. I should have done a ride with my 36 next but it doesn't have a seat at the moment.

Light weight big wheel (32 is sort of big) feels really good but I need to go bigger on the wheel or shorter in the cranks. If/when I get bored I will have to make up a light 36" tire and see how that handles compared to a standard 36.

I am not really that impressed with the G24 as a wheel size. I think the hub would be great in a larger wheel though.

[Nurse Ben]

All of that said, I like the acceleration characteristics and the size of the 29 much better. I've put off ordering new spokes for my 36 rim because I like how portable and comfortable the 29 is. For the 29 to be a viable top-speed machine though, it will require taller gears. As it is now, I would be happier with a 29 if it was by default 1:1.5, and geared up to 1:2.25 or so. These ratios are rough, and 'ideal' is of course different between riders, but I can climb up most anything in high gear, so for me that means it could stand to be a bit bigger.

+1

I've ridden 24, 26, and 29 munis, plus have a 36er. I can more of less use my 29 and 26 interchangeably since the tire diameter is nearly the same (Larry 3.8 and RR 2.4), but find a 24x3 to be quite twitchy. The 29 x 2.4 in contrast to a similar sized 26 x 2.5, the 29er feels like it bridges obstacles better, but feels slower to respond.

I have ridden my 36er mostly on jeep roads (dirt and gravel) and find that it rolls great ONCE IT GETS GOING, but it is SLOW TO STOP. The 36er has a huge amont of rotational inertia, so it can get to be too much, esp at slow speeds, so not exactly graceful. If I were riding just open road, I'd use a 36er, but if I knew I was going to have mixed surfaces or have to do some agile movement, such a riding in traffic, a geared 29er would be my first choice. Also, the geared 29er is going to allow a low gear for climbing, whereas in the 36er you are stuck with a high gear or a higher gear.

Off road XC, 29er fixed or geared, hands down the best choice.
Off road technical/DH 26, add a guni for making the connecting roads go faster...