So am aware I am probable missing something really big but…here it goes.
The gear ratio of a 29”er with 127mm cracks is 5.8:1 ratio
The gear ratio of a 36”er with 152mm cranks is 6:1 ratio
So my big leap is with a rider pedaling at the same RPM on both unis on a flat smooth road wouldn’t the two go the same speed? I am aware that with smaller pedals come less control, but for speed on a flat road they should go the same speed right?
The gear ratio of a 26”er with 102mm cranks is 6.5:1 ratio
The gear ratio of a 29”er with 114mm cranks is 6.44:1 ratio
The gear ratio of a 36”er with 140mm cranks is 6.54:1 ratio
With all things being equal shouldn’t all 3 go about the same speed? I apologize if this is too simplified…please set me straight I am new to all this.
This line of thought came into my head because I wanted to see what my 26”er rode like with 197mm cranks and my answer was like a 20” wheel with 152mm cranks.
Ok that I do understand, the 36" will roll further with each turn but with shorter cranks a rotation is quicker that is why when you put a shorter crank on any uni it you can go faster, as long as you can control the uni.
If you put a 170mm crank on a 36"er and raced a 29"er with 114mm crank and both people were equally fit and skilled uni riders the 29" uni rider would win right?
I like my 29er, cause I can ride flat or hills with 110mm cranks. The 110s make the amount of energy needed to keep momentum going minimal. My legs travel so little it really feel like I am ridding something unlike a uni.
Now if you put 110s on a 36er you would be pretty screwed in most situations. to be able to ride hills on a 36er you need much longer cranks, making the pedaling feel like more work, even tho you are traveling further.
I think a 29er with 110s is faster in a city setting with hills, than a 36er would be.
A 29" will go faster than a 36" if it’s pedaled faster. Your first post mentioned RPM. At any given RPM the 36" will naturally go faster. Shorter cranks will allow a 29" to go pretty fast, but it will always be at a disadvantage on RPM no matter what. You will always have to pedal it faster, even to go the same speed as the 36".
I raced the Marathon at Unicon last summer on a 36" with 102mm cranks. With 110s you’re only screwed if there are lots of hills, or steep hills. Unless your name is Beau Hoover, in which case you’re still ahead of everyone else.
Of course Beau is now riding 150s, and doing MUni in high gear!
Yes John I definatly miss stated the “Same RPM” thing. So then when the rider of the 29"er runs at a faster RPM to maintain the same speed as the 36"er then he should tire out faster or have to reduce his RPM’s (speed) quicker then the 36"er…right?
As a general rule, a strong rider on a 29er can keep up with strong 36" riders on mixed terrain, if he is using shorter cranks. The 36" riders have a higher burst speed, and tend to be more comfortable on longer rides. Not many people choose to do long-distance rides on a short-crank 29er, because spinning tiny cranks all day is hard on your seat, thighs, and back.
Exception: 29ers are much better than 36ers at pure hill climbing, due to a huge difference in rotational weight. If anyone ever comes up with a lightweight 36" rim, tire and tube, they might do fine for climbing, but with current technology you should take the 29er every time, if you’re doing a pure hill climb.
That is a big factor which people seem to overlook when making comparisons between wheelsize and crank length. It is also a reason why 28" is better than 29" for hillclimbing on roads, because what is the point in carrying extra rubber weight that gives more friction? I’ve ridden my 28" up the road on Mt Taranaki twice, and I doubt I would get very far up it on my 36", partly from lack of motivation since I have already conquered it on the smaller wheel. The unknown quantity of a ride never done before helps give you energy at times.
With this reasoning I thought a geared 28" might be faster overall on a long hilly ride (like 100miles around lake Taupo) but Tony Melton seems to think the geared 36"s make up for it on the flat and downhill. I think geared 28" would keep you in a safer realm of speed and keep the average speed up the weight down. Purely speculating and those who own the geared cycles probably know best.
It seems pretty clear that geared 36ers are faster than geared 29ers on mixed terrain. See RTL. The rider is more important than the cycle: Ken on his ungeared 36 was faster than a lot of geared 29er riders, and Vince on his geared 29er was faster than some geared 36" riders. But a geared 36" has a better gear for flats and downhills, and a better gear for many uphills than a 29er, because both of its gears are usable, while the 29er in low gear with 125mm cranks (which is what I think all the 29er riders were riding) is pretty dang slow. The geared 29er is faster than the geared 36 on hills where you can stay in the high gear on the 29er (for me, up to about 5% grade), and in low gear, the 29er is faster on hills that are long and steep enough to make weight a significant factor. But overall, the geared 36 is faster, which is part of why the only team that had three geared 36ers won RTL.
Yay for coker muni! I also rode 102s for Unicon and I usually use those or 114s for riding. I can make it up almost any reasonable hill on 114s but but comes a point at which 125s just make the ride more fun, and less painful such as the long distance fun ride at NAUCC last year. (1000m of climbing in 25k)
It wouldn’t matter that much; most of the people who show up are pure Coker riders anyway. And if I showed up on my 29er, I’m sure I wouldn’t get kicked out (plus they couldn’t drop me, anyway). The Coker-only thing is just to keep casual 29er or smaller-wheel riders from slowing down the group.
This surprises me. I have not put in enough time on a 36er I guess. I just cant see all the stop and go(which a big wheel and short cranks does not do very fast), and idling being very practical.
Maybe its just that the streets in Boston are crazy and don’t make sense.
I love 110’s too, it’s my general riding length for a 36" Unguni on mixed terrain. I did about 1/3 of the Alps Unitour on it, which was full of hills.
But crank length is a pretty personal thing, as much dependent on your height, eye colour, leg length, star sign, pedaling style as anything else.
On the topic of 29’er speed, again, it’s not a simple relationship between crank to wheel ratio, but it’s a nice way to think about it. Klaas Bil explains it well in this Article for Adventure Unicyclist
I’ve seen someone like Ryan Atkins ride at close to 30km/hr on 90mm cranks/29’er. I’ve seen Yuta Ando cruise comfortably at 25km/hr on a 65mm/28" to win the Unicon 12 10km race. The fastest I’ve ever gone on a 100mm/29’er is 28-30km/hr on the flat during Uninam, but that was just a very short burst.