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Old 2018-04-06, 10:47 AM   #1
Blaznee
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29" crown issues

Hello,

I'm posting here to get some help with crown issues.

I've read several topics about, but it doesn t solve my problem, I saw everywhere that round tires and high pressure would help, and big apple 2.0 tire wasn t sensitive, but with me it s the opposite.

I'm riding the 29" with a dominator 2 rim, big apple 2.0 tire inflated at about 60 psi, any small crown is very sensitive, and when crown is more than about 15% I can't control the unicycle anymore

At same time, I also have a 24" muni with a 3" fat tire (duro) that I ride with low pressure (about 18 psi), and with 15% crown I don t feel anything, even with 30% I don t have any problem, so I don t understand anything.

Any suggestion please ?
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Old 2018-04-06, 12:08 PM   #2
OneTrackMind
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Try a Maxxis Torch.
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Old 2018-04-07, 12:19 AM   #3
song
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Quote:
Originally Posted by Blaznee View Post
I'm riding the 29" with a dominator 2 rim, big apple 2.0 tire inflated at about 60 psi, any small crown is very sensitive, and when crown is more than about 15% I can't control the unicycle anymore
Very strange! I ride exactly the same setup and don't have any trouble with road crown at all. I have experienced this trouble before, but only on my 20" with a Hookworm tire. In that case, I found that higher tire pressure was helpful.
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Old 2018-04-07, 08:32 AM   #4
Blaznee
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I tried different pressures on the 29 but didn't noticed any difference, from 20 psi up to 60", but I noticed on the 24", the higher is pressure, the more sensitive it is (at 18 psi it s not sensitive at all, but since 30 it becoming much more).
I guess the deformation of the tire on the road compensates for the crown instead of affecting the whole unicycle when pressure is too high to allow the tire deformation, but it doesn't work on the big apple, only on fat tires.

I also noticed that it s much more sensitive on left side crown more than on right, don't know why (never got such a behaviour on my other unicycles).
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Old 2018-04-07, 08:33 AM   #5
Blaznee
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I tried different pressures on the 29 but didn't noticed any difference, from 20 psi up to 60", but I noticed on the 24", the higher is pressure, the more sensitive it is (at 18 psi it s not sensitive at all, but since 30 it becoming much more).
I guess the deformation of the tire on the road compensates for the crown instead of affecting the whole unicycle when pressure is too high to allow the tire deformation, but it doesn't work on the big apple, only on fat tires.

I also noticed that it s much more sensitive on left side crown more than on right, don't know why (never got such a behaviour on my other unicycles).
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Old 2018-04-08, 11:38 AM   #6
OneTrackMind
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Eventually you learn to deal with camber through technique. It is hard to say exactly what it is.

One way that might help learn is to take on short sections of exaggerated camber. Once you can routinely deal with them, ordinary cambers will no longer be an issue.

I ride a lot on footpaths (sidewalks) that are sometimes crossed by steep driveways. There are a couple of very steep ones made worse by nasty steep approaches that flummoxed me for a long time. Now ride straight across them.

https://www.google.com.au/maps/@-28....7i13312!8i6656

As far as I can tell there is some part of the pedalling cycle where I somehow reorient the unicycle back onto the correct line. When I first learnt to cope, the reorientation was almost a momentary still stand but it eventually morphed into something more subtle that I can no longer pinpoint.

However I do ride with tyres that have very flexible carcasses which I believe help reduce the effect. My 36 has a handlebar which also helps.
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Old 2018-04-08, 12:36 PM   #7
Blaznee
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I've learned to deal with on my 20" muni, it's ok with short passages (100m or less), but the whole road is cambered on 20 miles, it gives me knee pain to correct all time long.

Thanks for tips
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Old 2018-04-08, 06:46 PM   #8
Blaznee
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I just noticed that my rim (Nimbus dominator 2) seems to be smaller than 29", the actual tire is 28" and not 29", I am supposed to use 29 tire or better 27.5 ? or 28 only.
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Old 2018-04-08, 10:45 PM   #9
song
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A 29 is only called a 29 for advertising reasons, I think. It is actually more like a 28, unless you put some sort of huge fat tire on it. 27.5 is a different, smaller size that was only invented recently, as far as I know, though they are always ridden with a fat tire, so maybe in real life they are usually not smaller in diameter than a 29. I have heard that a 29 is actually the same diameter as what we usually call a 27, which is the standard size for road bikes, but a 29 is built to hold a much fatter tire.

Once you go non-metric, why bother with annoying things like exact measurements? I think that's how the reasoning goes, at least. Since World War Two, as every American carpenter knows, the board called a "two-by-four" has ceased to be 2" x 4" and has now shrunk to 1.25" by 3.25."

It is possible that some of these facts are not quite right, in which case someone will hopefully correct me, but I guess getting it wrong is half the fun of this system! Enjoy!
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Old 2018-04-08, 11:00 PM   #10
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Quote:
Originally Posted by song View Post
...It is possible that some of these facts are not quite right, in which case someone will hopefully correct me, but I guess getting it wrong is half the fun of this system! Enjoy!
Bike wheel sizing is even sillier than you think. The old fractional 27" size used on some road bikes is actually a BIGGER rim than what is now commonly called 29" in north america. the 27" size had a bead seat diameter (BSD) of 630mm while 29" has a BSD of 622mm, which is the same as the modern 700C roadbike and european 28" cross bikes.

If you really want to get into the weeds I would suggest Sheldon Brown's article: http://www.sheldonbrown.com/tire-sizing.html



As to the original complaint of the road crown affecting the 29 more than the 24 I don't have much useful advice. Maybe try turning your wheel around in your frame to see if the wheel is dished and the fame is bent (but don't ride like that unless you also swap the cranks over, you will wreck your pedal threads). If it's not a mechanical problem perhaps try riding on the other side of the street for a while to balance things out.

Good Luck!
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Old 2018-04-09, 09:00 AM   #11
Blaznee
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Thanks for explanations about tire sizes

About bikes, can we use bike tires on such an unicycle ?
I guess there s already topics dealing about, but I didn't managed to find any.
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Old 2018-04-09, 09:19 AM   #12
kunstrasen
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Yes sure. You can use bike tires.
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Old 2018-04-09, 05:43 PM   #13
TMason
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Quote:
Originally Posted by Blaznee View Post
I also noticed that it s much more sensitive on left side crown more than on right, don't know why (never got such a behaviour on my other unicycles).
On flat ground do you make smoother right turns than turns to the left?
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Old 2018-04-09, 08:35 PM   #14
Blaznee
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Originally Posted by TMason View Post
On flat ground do you make smoother right turns than turns to the left?
no, the opposite, I turn smoother left than right.
about the crown more on left than right side it's only on my 29. On my 20" I don't feel difference between left/right.
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Old 2018-04-09, 09:34 PM   #15
Canoeheadted
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More time on the 29.
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