I’ve got a Schlumpf 29" unicycle with the Schwalbe Big Apple tire. It’s a sweet ride and I can cruise at a pretty respectable speed – not 20 mph like I’ve seen mentioned, but 14-15 mph for reasonable distances.
However, I’m not thrilled with the tire. If the road is tilted then I have to struggle to ride straight – typically I stick my hip out in the direction the road tilts and stick my shoulders out the other way, but that’s not particularly comfortable.
I have similar problems when I try taking a corner at high speed.
My theory is that the problem is an imbalance between how easily the tire turns and how much I need to lean. Leaning the unicycle causes the unicycle to turn. Leaning the unicycle is also necessary when turning in order to counteract the centripetal force. At around 8-10 mph on my Schlumpf 29" these forces are balanced, but at higher speeds I need to lean more to counteract the increasing centripetal force, but I can’t lean more because then I will turn more. This either makes me feel out of control on turns, waving my arms madly, or it forces me to slow down.
So…
I’m looking for a 29" tire that is less sensitive to side slopes and has a higher ‘natural turning speed’. Or, I’m open to other theories on what the problem is (gyroscopic effect?) and possible solutions. I’m happy to be able to ride nice and fast in a straight line, but I may occasionally need to go around corners.
I switched from the Big Apple 29x2.35 to the 29x2.0" on my geared 29er, and the difference is night and day on side slopes. The 2.0" can totally carve turns and isn’t affected by road camber, where I’d have to fight it on the 2.35". The smaller tire is a little less cushy and isn’t quite as fun off-road, but I’m definitely going to be running the 2.0" for RTL and for any other distance road unicycling I do.
The Marathon Supreme is hard to find in the U.S., but I just got one from Chain Reaction in the UK; I haven’t ridden it yet. (One of those tires will wind up on my ungeared 29er, which is in a Semcycle XL frame that has less than 2mm of clearance with the 2.35"). I’m also using the lighter Schwalbe tube at your previous suggestion.
By the way, I inattentively installed the Big Apple 2.0" backwards and I’ve been riding it that way; I doubt it makes a noticeable difference.
I changed the tube at the same time I changed from 2.35" to 2.0", so I can’t isolate what made which difference. But it was definitely a lot different (better, for geared road riding).
The biggest problem with the 29x2.35" is that you can be blasting down a hill in geared mode, get to a spot where the road is slanted, and suddenly have to fight for your life to try to keep the wheel straight. That doesn’t happen on the 2.0".
I noticed the difference between the 2" and 2.35", but mistakenly didn’t attribute it to the tire. I have the 2" on my ungeared GB4 29, and never had a problem with road camber. More recently, I’ve been riding a lot on BlueShift, a geared 29 with the 2.35. I found myself with all the symptoms Bruce described, and chalked it up to the gearing. Also never rode one right after the other for comparison, so didn’t get the association to click in my head.
I have a 29" Oracle with a 2" Big Apple tire that I’ve ridden for 100 miles on paved bike trails. From day one I had trouble with it veering to the left. It was horrible the first day I rode on a trail but has gotten better. These days it’s very noticeable when the trail slopes up from left to right. When the trail is sloped like that I have trouble keeping to the right side and occasionally get scolded for riding in the middle of the trail by bikers. Riding in the street on the right side of the road is fine but I’d rather ride on bike trails away from cars. I thought this problem would go away over time … maybe it will but it’s really annoying in the meantime.
Would a Marathon Supreme tire be better than a Big Apple? Any thoughts on this?
Try experimenting with different tire pressures. I find that the Big Apple 2" tire worked perfectly for me and would track smoothly at a wide range of speeds on tracks and roads with fairly decent cambers.
Turning at high speed is something that is tricky because the amount of frame lean required for a smooth turn depends on the tire and its pressure, whereas the amount of body lean depends only on the speed. But, you seemed to be concerned with straight-line riding. So, first experiment with different tire pressures, then try different tires. Good luck!
A wider profile rim will change the shape of the tire, which could make it worse or better, just something to think about.
Unicycles are prone to this problem, consider increasing control by adding a bar, using a flat seat to improve hip articulation, or changing to shorter cranks to lateral torque
I’ve tried a few things, shorter cranks, flatter seat and lower tire pressure.
I almost bought bars during the big sale but didn’t. Not sure I’m ready for those yet.
I wonder about the rim size. Maybe I’ll change to a Velocity Dyad or Rhyno Lite. Matching rims with tires is quite a task for a new rider. So much info out there on the web to sift through.
I haven’t tried either of the tires you asked about, but I can tell you that the least troublesome and most fun setup I’ve tried so far was my first 700c one, a 37mm Panaracer Pasela on a Rhyno Lite rim. That’s about a half inch less than the usual 29" tire but still a lot more than the proverbial “pizza cutter”. (Probably wouldn’t go on a Dominator 2 rim though.) I’ve had a couple of wider tires on lately, more like 2" wide, but so far just noticed the extra weight and extra work fighting them. The Pasela was more nimble and it handled road bumps and occasional gravel just fine. FWIW…