I’ve been working on hopping lately (mostly rolling) and am wondering what factors influence hop height most. I have been doing most of my riding on my nimbus x 24 with a hookworm on it. It’s pretty light 13.5 lbs. I can easily roll hop up smaller curbs, but had a hard time on bigger ones. I recently picked up a kh 20 and found I could rolling hop up all the big curbs fairly easy. I think the weight of the uni’s are close to eachother, so I’m wondering what gives the the advantage on the 20?
Is it the higher volume tire?
Is it all in my head (this wouldn’t surprise me at all)?
Is there a mechanical advantage to hopping on a smaller wheel?
Is it tire pressure (it seems like I can have the 20" tire much lower psi than the 24 because of the difference in volume)?
Maybe some of you guys that have experience riding both could shed some light?
Now im not sure about this one but iy may just be the radius of the wheel as it would be 2 inches smaller but at the same time your 2 inches lower to the ground 
I’m the same. I think its because you pratice more on one uni then the other (well for me it is) I can jump further on my 24" then my 20" because of teh speed.
It might be your speed, on the 20" your going slower to compres your tyre more and have more of a reaction time then on your 24" because your going faster and have to do every thing faster eg compres your tyre and flick your ankels forwed to get the hop…
But I dont know it maybe that it may not be
Rider technique is probably the biggest factor, followed by tire volume. Not volume, but cross section. Naturally the 24 will have more volume.
Technique covers being used to one wheel size more than the other. If you’re more comfortable doing rolling hops on one over the other, that will make a big difference. Also there might be a bit of hesitation with the larger wheel if you’re used to the smaller one. The larger wheel is a little more scary.
Let’s see…calculate this for each uni:
Multiply the circumference of the wheel times the volume of the tire. Divide result by pie. This gives you the nyuk factor for any given wheel. Now weigh yourself, wearing what you normally wear, with your uni. Add the square root of this figure to the nyuk factor for each uni and you will have…
No, that doesn’t make sense the more I think about it.
Really I just wanted to post and say - “Wow, Anton got himself a KH!”
Don’t forget to think about crank length. Assuming a preference for a particular leg extension when the pedal is at its lowest, longer cranks increase the clearance for tucking when hopping with level cranks. There are various reasons to use longer cranks on a 24" wheel than one would use on a 20". Of course one could lower the seat on the 20" accordingly but it will be less comfortable to pedal seated than the 24".
I weighed the kh 20, it came in at 11.5 lbs. 2 lbs lighter than my 24, which is probably significant.
Today I found myself hopping much better, I think the practice is starting to finally pay off. I could easily make all the curbs around my house and also made the 7 inch concrete parking barrier I’ve been trying to jump over at the park.
Tomorrow I’ll take the 24 back out and compare. I think there isn’t going to be much of a difference though.
Just got back from riding the 24 again, tore it up! Rolling hops much higher than yesterday on the 20. So my conclusion is the Uni doesn’t make much difference. You just need to make sure your tire is nice and low (I was running about 22 psi in the hookworm). All the practice has finally paid off and I was getting some good hops from a foot away from the curb up onto it, it felt really good and was fairly easy.
I guess its time to work on more height, I’ve got to find a two set near home now.