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Old 2018-04-19, 02:12 AM   #46
johnfoss
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Originally Posted by Blaznee View Post
When road is cambered on right ( \ ) it's ok, not any problem, but when it's on left ( / ) that s almost impossible to control.
Even on flat road, it feels like a left camber, and If I don't correct it turns left quickly.
If it still turns left when you ride on level ground, it would seem that your riding position (on that unicycle at least) is biased toward one side. You might be sitting a little off-center on the seat, something might be off-center in the wheel build or its fit into the bearings, or a combination of both.

I'm sorry I haven't read the whole thread recently, but if you have an imbalance while riding on flat ground I think you need to start from there. Why go crooked on your 29" but not other unicycles? If you can figure this out it should help.
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Old 2018-04-19, 03:14 AM   #47
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Originally Posted by song View Post
Blaznee posted a photo of his uni on the "Pictures of your latest ride" thread, and, in addition to having the same tire, rim and unicycle as I do (except for the handlebars, which I don't have), he also has his tread pointing in the same direction.
That tyre reminds me of the first new tyre I ever bought for my 20 inch unicycle, a Maxxix Ringworm. The difference was that the little patches in the middle alternately crossed the centre line of the tyre.

I had very little riding experience at the time but that tyre made the uni go anywhere but straight. As soon as it tilted slightly to one side it would keep going that way and throw me off. I gave that tyre away and bought a Hookworm online.

I suspect Blaznee's tyre is not ideal for a uni, particularly when ridden by a beginner.
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Last edited by OneTrackMind; 2018-04-19 at 03:15 AM.
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Old 2018-04-19, 08:36 AM   #48
Blaznee
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I'm beginner on the 29" (about 400 miles only), but not on unicycles (about 18 years of experience).

I'll try to reverse frame / seat post.

I also guessed about a wrong sitting position, but I've tried to change during riding (move left, move right, up, front, rear, diagonale...) and it changes nothing.
But I noticed that the top of seat post (where we screw the saddle) isn't laterally horizontal, probably a hardware issue. If that's the source of the problem, reversing the seat post should reverse the camber direction.
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Old 2018-04-19, 10:54 AM   #49
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I suspect it is the tyre amplifying the effect of a slightly tilted seat.
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Old 2018-04-19, 11:20 AM   #50
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Originally Posted by Blaznee View Post
I'm beginner on the 29" (about 400 miles only), but not on unicycles (about 18 years of experience).
When I first started riding that same 29, I had only been unicycling for one year, and I never had any problem with road camber on that unicycle. Your non-horizontal seatpost top is almost certainly the problem. Maybe you can get Unicycle dot com to give you a new one.
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Old 2018-04-21, 10:36 AM   #51
Blaznee
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I have checked the rim and wheel, and there's not excatly same distance between the frame and the rim/tire on left side and on right, about 2.5mm when frame is vertical, the wheel is bit like that: \
and the saddle is also a bit lower on right side than on left, so it's like if I put an angle on left when I sit normaly, + the wheel already a bit on left, it increases the left turning issue, I guess it explains my problem

is it normal to get such a difference between left/right side distance with frame/wheel ?
if it's not, how can I correct it ?
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Old 2018-04-21, 01:25 PM   #52
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The rim might not be centred on the hub or one frame leg could be slightly longer than the other or the frame may be misaligned with both fork legs bent in the same direction.

Does the wheel still have the same bias if it you put it the frame in the other way around? That will tell you whether it is the frame of the wheel.

Does the axis of the seat tube run exactly in the middle of the space between the bearing holders?

Note 2.5 mm at the rim on a 29 inch wheel is less than a millimetre difference in the length frame legs on a 100 mm wide hub. It isn't unusual and some riders adjust it with a shim between the bearing and the frame. I doubt that such a small amount matters that much.

If it is the wheel not centred on the hub it can be adjusted but tightening the spokes on one side and loosening on the other. However I would hesitate to suggest you fool around with the spokes without learning more about truing wheels first.

I reckon the seat post is more likely the issue and I still don't like that tyre tread pattern.
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Old 2018-04-21, 01:45 PM   #53
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So if I understand you correctly, you've got a wheel that goes like this \ and a seat that goes like this /

If anything related to a unicycle can be called serious, this is definitely a serious problem, but at least now you have a diagnosis! Figuring out a repair strategy might be easier in person than over the Internet, but as a preliminary suggestion, maybe check to make sure your wheel's bearings are seated where they are supposed to be in the frame and/or in the bearing caps. I doubt this is the problem, as I don't think you could have ridden 400 miles if it were, but have a look. If you could loosen the four screws and then just snap the wheel into its correct vertical position, that might fix everything. If your frame is bent, though, that will be much harder to fix.

OneTrackMind's suggestions are excellent and give you many more options, though I definitely don't think the tire tread pattern is the problem, for reasons mentioned earlier. Are you sure you rode 400 miles on that thing, though? The tire in the photo you posted does not look like it has 400 miles on it, but maybe the photo is old. Oh well, good luck!
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Old 2018-04-21, 01:58 PM   #54
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I've tried to reverse wheel in the frame, same result in same direction.
I put a piece of aluminum sheet between frame and bearing, let see if it's better.

P.s. I ride on grass as much as on asphalt, it saves the rubber a bit more than asphalt only.
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Old 2018-04-23, 07:26 PM   #55
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After wheel angle correction, it's a bit better, but still not like it should be.

I can now handle very low camber on left side (like on the first picture), but on flat road it still feel like a left camber, and I need a right camber (about same angle than the first pict) to feel like a flat road with my other unicycles.



On right camber it didn't changed, can still handle low/medium camber like the next picture but it's tiring, on 1 or 2 miles it's ok, but on long rides it's hard (while with my others unicycles I can handle 15 miles without problem).



I'll try with a different tire.
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Old 2018-04-26, 04:52 AM   #56
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Originally Posted by OneTrackMind View Post
I suspect it is the tyre amplifying the effect of a slightly tilted seat.
I noticed a lateral tilt issue on the saddle posts on a couple of nimbus unis i had.

I corrected them with a combination of filing and washers but I don't recall it making much of a difference but I also don't recall what prompted me to check and resolve that.
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Old 2018-04-26, 08:30 PM   #57
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Originally Posted by Blaznee View Post
I can now handle very low camber on left side (like on the first picture), but on flat road it still feel like a left camber, and I need a right camber (about same angle than the first pict) to feel like a flat road with my other unicycles.
Oh, that's what you were asking about! Somewhere deep in the archives here are a few reports from people who've tried unicycling on banked velodromes, and none of them had a good thing to say about it. We don't go nearly fast enough for the banking to help. At our speeds, it tries to make a unicycle turn the wrong way. All reports said that it was very awkward and uncomfortable.

On the other hand, riding a proper track bike on a steeply banked velodrome is a real kick. I've only done it once, on a track with the turns banked at 42°, and I can't express how much fun it was. We were told to keep our speed above 12 mph/20 kph in the turns or else we would slide down the wall!

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Old 2018-04-26, 11:00 PM   #58
OneTrackMind
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If it doesn't turn out to be the uni causing it, that just leaves the rider.

Could one leg be shorter than the other?

Or Scoliosis?
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Old 2018-04-27, 08:20 AM   #59
Blaznee
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Originally Posted by LargeEddie View Post
Oh, that's what you were asking about! Somewhere deep in the archives here are a few reports from people who've tried unicycling on banked velodromes, and none of them had a good thing to say about it. We don't go nearly fast enough for the banking to help. At our speeds, it tries to make a unicycle turn the wrong way. All reports said that it was very awkward and uncomfortable.

On the other hand, riding a proper track bike on a steeply banked velodrome is a real kick. I've only done it once, on a track with the turns banked at 42°, and I can't express how much fun it was. We were told to keep our speed above 12 mph/20 kph in the turns or else we would slide down the wall!
I did the tries only in velodrome, cause it's easier to test and see.
By the way on my other unicycles I can ride the same velodrome without any issue, whatever the speed.
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Old 2018-04-27, 08:20 AM   #60
Blaznee
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Originally Posted by OneTrackMind View Post
If it doesn't turn out to be the uni causing it, that just leaves the rider.

Could one leg be shorter than the other?

Or Scoliosis?
I thought about the leg issue, but why would I have that problem only with 29 and not with 26 at all ?
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