Hello y’all fellow unicyclists!
I have a Qx unicycle from 2016 running a 2"4 Maxxis High Roller II in a Qx frame - generation before the RGB model. It’s the squared frame, only compatible with disc brake. See these pics:
The tire is great for riding uphill - nice grip - but is too narrow to handle great drops. I’d like to go for a bigger tire but I can’t find how big this new tire can be. Would a 2"8 tire fit? I think a 3" tire would be too big.
Thanks for your help! 
Just thinking, your tyre doesn’t look centred in the snow image, so you are losing a lot of width available to you.
Yes, it has been centered since this picture has been taken - two years ago. However, I don’t know how I have been able to ride with this decentered wheel. 
Cool. Then the next concern I have for you is the vertical clearance - I am doubtful a 2.6" tyre will fit (unless your pic has your frame at an angle). You might be at the max already.
I think there’s an angle. As far as I remember, the photographer was lower than I was so the clearance is probably greater than what we see on this picture. I sadly can’t measure it ATM.
I was hopping that some of the members of this forum have already tried to put bigger tires in this frame…
I have such a QX frame, a 29er frame with a 27.5 wheelset. It’s not exactly the same frame since mine has the magura mounts, but i think the overal geometry did not change in this time (maybe @qu-ax can tell). I run a Schwalbe Nobby Nic 2.8" on the QX rim (42mm?) in it. It’s fine as long as it is centered but i would not recommend on going any wider if you’re planning on doing uphill with it.
Thanks @Eric_aus_Chemnitz yes, width is similar, however, if you run a 29" with a 27,5" clearance, there’s certainly more top-room - @Maxence seems to run a 27,5 wheel plus frame.
I know in the former forum there was a swiss guy who had put a wider tire in a 29" frame, too, but I am not sure if it’s here anymore.
A general clearance is hard to tell, since tyre width depends a lot on tyre makers. A 2,8" Maxxis is often as wide as a 2,5" Schwalbe etc.
Thanks for you replies. So I won’t be able to know exactly which tire fits in my frame… Sad 
I’ll just try and send back the tire if it does not fit.
I think have a look at your top clearance again before buying, I don’t think you have a lot of space there.
Sure. I’ll try and measure it before buying.
Nothing has gone lost during the migration.
You’re right, it’s here: Selling my Qu-ax 29x3.00, loc: Fin, Europe
On the last picture we can see there still a bit of clearance in the frame. Not much but still sufficient. I’ll probably go for a 2.8" tire which should fit.
Thanks all!
On my 27.5 I changed the 2.4" High Roller II to a Specialised Ground Control 3"
Like Eric I have the frame with Magura mounts. And yellow Qu-Ax stickering, not “QX” as in your image.
If you like I can measure the frame width and clearance tonight.
Tanks @Quax1974. If it fits your frame, I don’t see why it would not fit mine. They probably have similar measurements. If you could measure it tonight, that’d be great
Hi, 29x3.0 fits in my 29" QX frame.
But i ride nie the Schwalbe Bobby Nic 29x2.8 with better performance at higher speed as the Big Daddy 29x3.
Regards from germany,
Sven
Thanks Sven. Looks like there’s not much clearance. I’ll probably go for a 2.8" tire.
Thanks @Fairlight, that was the photos I remembered.
The width from inner leg to inner leg of frame at tire-height is 86 mm +/-2 mm.
The high from center bearing-cup to inside of frame crown is 376 mm +/- 1,5 mm on the disc! QX
@Maxence: in my 27.5 frame I have ~ 2.5 mm clearance, per side, with the 3" Ground Control tire.
Above the tire about 10 mm
Cool! Thanks for your measurements
Yesterday I have thought about it and I have measured my 27.5" x 3 wheel in my RGB frame and my older Qx frame. I had approximately the same values. I could certainly try and put my 27.5" x 3 wheel inside my Qx frame but I don’t want to mess up with my brake settings.
So I’ll get a 2.8" tire and it’ll work perfect!
Thanks again to all of you!
