Unfortunately I don’t think that will help much. You can fit cranks which will give a similar level of torque, but the difference in length means you use very different parts of your leg muscles with a geared uni. Getting good at spinning tiny cranks is a specific skill, but guni riding is another kettle of fish. I definitely can’t go up hills in high gear on my g36/150mm which I can do with my ungeared/100mm.
The best practice/training to prepare your legs for guni riding is a bike. That will have more similar length cranks, and you can push harder in higher gears on them than on any short-cranked ungeared uni.
The coloured chart is great. Thanks Eric - it’s an easy way of browsing TGRs.
The general public supposedly associates unicyclists with clowns, whereas I have always associated unicyclists with nerds. this fantastic post amongst several others this week alone has vindicated my thinking. Wow. I love it!
What? Oh, you’re new here. Yup, it’s a nerd-o-rama! I especially like when people bring in physics equations that tell you something, but usually not in relation to the realities of the situation under discussion…
I think riding a GUni in high gear has more in common with riding a bike in terms of leg load than it has with single speed uni regardless of crank length.
I have a 26" Nimbus with square tapered 152mm cranks.
I noticed in my garage I have a beat up punk/runt bike like this one with 92mm cranks.
If I succeed in putting the 92mm cranks on my nimbus my TGR will change:
152mm TGR = 2.17
92mm TGR = 3.59
That would give me a TGR similar to a Coker with 130’s.
TGR is the “speed potential”. So I should have the potential to go as fast as this Coker.
I’m excited about trying this. Will it be a no brainer to just ride and be fast. Or is there some lack of technique that will keep my “potential” from becoming realized?
Gain ratio ( I am not a fan on the term TGR since most of us don’t have gears) is only one factor on how fast you will go.
When riding a 29 with 102s I can get top speeds about the same as my top speeds with a 36 and 127s (30-35km/h) but I feel like I have more control with the 36 and am able to keep a higher average speed with the larger wheel and longer cranks but similar gain ratio.
I crashed pretty hard a few years ago using 102mm cranks and no-loner feel comfortable on anything shorter than 114s. Probably just a mental block and I will have to put some short cranks on a 20 to get over it.
You can continue to use the term TGR and secretly think Total Gain Ratio.
I use “gear” also as reference to the “gear” resulting from the crank being shorter than the wheel radius. People on this forum have called this “gear” for years. Looking at it that way, every unicyclist rides geared
A 26" with 92 mm cranks is still a reasonable unicycle. You will need quite a bit of training to acquire the technique of spinning really fast (meaning it is not a no-brainer), but then I think you would be almost as fast as with the same amount of training on a Coker with the same TGR.
(BTW, how did you calculate 130? My calculator gives 92 * (36/26) = 127 mm.)
Yup, lots of nerds here! I’m not a math nerd at all, but there sure all nerds of all types here. I might be a nerd with religion and philosophy and just knowing lots of random stuff. Math is definately not my forte.
Thanks for posting that Sasquatch! Just thinking about this the other day! Glad i checked out what this thread was about.
I didn’t calculate 130, I just moved over in the chart and estimated.
When I went to take the cranks off the runt bike, my 6 y.o. daughter put up a stink. Despite the rear tire being worn and pretty much busted, she still rides it sometime; earlier that day in fact.
And I don’t know if I could remove the cog off the one side and ever get it back on again. So I’ll have to investigate it further when my 6 y.o. isn’t around.
Unless there is clearance issues with your frame (unlikely) you could just ride with the chainring on there.
Repurposing is where it is at, you might have to send the kid to Grandmas place while you have your fun though.
If I were to buy cranks to make a fast 26 I think it would be in the 100-115 range. 92 might be a bit extreme (but when that’s what you got, that’s what you got)
Are 92’s a bit extreme because it’s a 26 or would that be the case regardless of wheel size?
If it depends on wheel size, then it would be cool to modify the chart. For each column in your chart you put a line showing the longest “recommended” crank length and a line showing the shortest?
I guess even if it doesn’t depend on wheel size, it would might be nice to have those lines… just straight across.
That would make it more obvious that although I might have the same TGR (26 with 90’s and 36 with 135’s both equal 3.39) I might be going too extreme with one.
I am a big fan of the concept and I took a good while to read this since I often find myself doing calculations on my unicycle. I was just yesterday thinking about the advantages of different sizes of wheels andthis sums it up pretty well!
When I first made the chart I highlighted the crank lengths from 165 to 110 since that is what I like to use but decided to undue the highlighting because some people like to crank away with 185mm bike cranks for big wheel MUni and some people are really good at spinning little wheels with ridiculously short cranks.
With the 92s you will probably be able to reach top speeds similar to a 36 with 130s but won’t have the same stability or control. That is exactly the reason I have pieces of my leg holding my shoulder together, but then I was pushing the limits a bit to far. You should be fine as long as you aren’t trying to squeeze every last ounce of speed out of your setup while wearing a large backpack. :o
It seems that for a non-geared uni it should be TGR = axle height / crank length
Axle height should be measured with the uni mounted so that it equals the length that it will be when riding. So the result depends on rider weight and tire pressure.
Firstly, I personally think that 92’s are not really extreme on a 26". Sask must be with me on that one, or his colour coding in the table is wrong. 92 on a 26" show between “allround road riding” and “hilly road rides”.
Secondly, it DOES depend on wheel size. That’s the whole idea of Sask’s table and the colour coding in it. E.g., 165 mm cranks make good sense on a geared 36" but not on a 20". Those lines you’re talking about are already in the table, as the borders between differently coloured areas. But it’s not a black and white picture, literally.
