What do you think is the ideal height for a fork crown above a 19" trials tire? Not tire clearance, but the height measured from the tire to the top surface of the crown, that affects how far above the tire your foot sits for foot-on-frame moves.
The spring/summer KH20 had a 45mm height above the tire; Fall 2005 has a 35mm height above the tire. Spring 2006 is currently spec’d as 35mm above the tire, but with a different gusset under the crown to increase tire clearance at this height.
To me, pros/cons are:
35mm (or as low as gives reasonable tire clearance under the crown):
A lower foot position increases stability since your legs aren’t as bent, and reduces the chance the crown could get in the way. Also helpful for people who want to glide “Japanese style” with both feet on the frame.
45mm: reduces the chance you’ll accidentally hit your foot on the tire during foot-on-frame tricks, depending on how you put your foot on the frame.
Although freestyle is my thing, I think closer the better even for trials. For instance, on my Semcycle XL Longneck frame that is just a couple of millimeters off the tire, I rarely ever drag my foot. I think this may be from a reasonable amount of experience on freestyle riding with lots of standing on frame and foot on frame skills, or it may just be natural. On the other hand, on my Nimbus 29er with rounded crown frame, if I ever one foot or one foot wheelwalk for fun sometimes my foot drags about 50% of the time. I guess the conclusion of that info is up to you, but there you go! Oh, and one quick question: does dirt and debris ever get stuck in between the frame and tire? If so, the closer crown may be affected by that, although I doubt that’s the case.
Tyre clearance isn’t as crucial on a purely trials-use frame, as rock, log, pallet, box & plank hopping, along with rail riding and other street tricks won’t pick up debris like a muni will. But if anyone wants to purchase one uni and use it for trials/street/muni/whatever, then some kind of basic frame (like the 2004/5 onza or nimbus) might be more suitable for them. Back to the point…
If you’re paying £80+ for a light, strong frame then I think making it as trials/street suitable as possible would be the way to go, rather than trying to cater for loads of different uses in one frame. IMHO, for trials & street a low tyre clearance & correspondingly low crown are more advantageous than any kind of artificial attempt to stop people accidentally putting thier feet on the tyre. Since the KH20 frames are used on street & trials unis, being able to have the seat artificially low (for trials) but still have a comfortable foot rest height for 1ft, WW & Gliding etc (street skills) is very important. I currently have the issue where my seat is very low for trials, and I struggle to get my foot to a repeatably decent position for 1ft (on a 2004 Onza Frame). A lower crown (by my measurements a New KH20 Alu frame would be 30-35mm lower at the crown than my current frame) would make this much easier. Even with this massive height (its at least 65-70mm above the tyre) I still rub my foot on the tyre transferring to 1ft every so often, which is something technique can cure.
Maybe some kind of texturing effect on the crown itself (like the DM close-crown frames) would help with foot positioning on a lower crown?
Oooh, now I’m just going to have to buy one… Damn you and all your incredible technological advancements :p. What kind of date are we looking at these new frames being available, I’d love to have one for next years BUC.
Personally i would perfer the 35MM over the 45MM just becasue there is less crown to get in the way. I guess the weight of the frame would not be effected much by the 10 MM diffrence in fork legth?
I think your frames are fine as they are right now (35mm) the only thing I think you might wanna change is your seat bases… ppl break them alot… the rest of your unicycles are fine.
As low a profile as possible. These are trials and muni frames, not freestyle, right? So why compromise performance in trials and muni for a secondary intention? You can get used to gliding with a low profile crown, but having knees bashed never stops being painful. While technique is more important, a low profile crown helps.
This is probably an insignificant point to make, but I guess having the effective frame leg length shorter would make it stronger, allowing you to use thinner tubing. I don’t expect the difference to noticable though.
I’ve only done a little bit of gliding and coasting (short coasting), but I know that I can’t picture myself ever really getting used to having the corwn closer to the tyre. I find it a real stretch to bend my foot back that far so that it doesn’t touch the tyre or only touches it lightly. I also almost never hit my knees and legs on the crown.
I think the 35mm would feel better than the 45mm option, it makes a much grater feel while one footed wheelwalking, or one footed riding… I can’t se the point of having a higher crown, makes nothing that i know of better…
I would want another inch or so in the seattube too!
This height places it in a criticla point while (trying to) do standup wheelwalk, to hit your ankle in it all the time…
Not saying it would be a longneck, only a slightly higher neck for more comfort!
Cool, I wasn’t sure before but I have the newest Spring2006 model!!
The short answer to your question is “no Kris, just leave be, it’s absolutely fine how it is!”
The general concensus amongst trialists and freestylers (who spawn street riders) seems to be that the lower the profile, the better, so, given that there’s currently a 6mm(?) clearance between the tyre and the frame, I think you could safely bring that down to about 3-4mm… maybe even closer? That would make the frame 32-33mm above the tyre.
It would definitely be a “strictly trials” unicycle though as opposed to how it currently appears to being marketed as a “Trials/MUni for kids” unicycle.
Beyond designing a wacky style of frame that allows the “foot rest” part of the crown to actually sit lower than the top of the wheel, the only other variable is the thickness of the crown which I suppose would most likely be weakened by any thinning, which seems totally unnecessary.
I’m no physisist so please don’t laugh if this is a really stupid question, but say you brought the clearance all the way down to .05mm, would there be some affect in riding from the air movement caused by the spinning tyre reacting with the very nearby frame? If so, would this induce you to design an aerodynamic “gusset under the crown”?
cheers
Pete
PS I discovered a park in Auckland the other day thats called ChrisHolm park… it’s a great sign to do a stillstand on too!
I think it’s important to leave enough room so that new models of trials tyres that may be a little bigger in diameter can fit. The Maxxis Creepy crawler only barely fits in my current frame (KH20 '03 or '04 or so) and I think it used to rub until the rubber wore down a little. Just a thought.
I think these little “circles” are for helping you keep your foot on the frame with 1-footed skills. These things have been phased out with the newer model 2006 frames (in the trials version at least).
