I like my Oracle 36“ uni. Except the 125mm is a bit wide for me - I keep hitting the cranks (zero Q) with my heels. Not all the time, but more often than I’d like. Because of that, and since it’s a lot of fun I’m planning to move to a 36er with 100mm bearing spacing.
I’d love to go the carbon rim route, but right now that’s not an option. My preferred option (at the moment) is to re-lace the wheel using the existing rim and spokes. Due to the new hub being narrower, the existing spokes end up being too long by 0.7mm and 1.5mm, respectively.
In my opinion that shouldn‘t be much of an issue. What do you people think?
It hopefully will be fine, but you may need to check whether they were either a bit short or a bit long for the existing hub/rim combo. Unicycle.co.uk spoke length calculator page says
Blockquote
When selecting replacement spokes they can be +1mm to -3mm without any problem
I feel like this is mostly a technique problem. When i was first learning on a 24" with 100 mm bearing width i would often hit my ankles and after a lot of blood and pain i stopped doing that.
You should buy new spokes, as old ones will only cause trouble when truing your unicycle. Plus, you’ll need shorter spokes anyway, since you’re going from 125mm to 100mm. I had to touch my spokes twice on the 24" Muni. The spokes didn’t like it because they had already been trued, and now I have a slight radial runout, and you can tell the spokes were already under tension. If I’m lucky, I’ll be able to true the wheel better, but right now I don’t like it because it’s not centered well.
Assuming the original spokes are perfect length or slightly too short then you should be fine reusing them.
You can remove the rim tape and have a look at the nipples from inside. If there are still a bit of visible thread (like below) inside you can reuse them without issue.
If the spoke is already flush with the bottom of the nipple like below then I would add some “nipple washers” to add a bit of length so the nipple does not “bottom out”.
I would also recommend brass nipples; aluminum ones break very quickly. The aluminum nipples also spin round, which is what I had on my unicycle. The spokes were so tightly connected to the nipples that you couldn’t turn them anymore, and I had to re-spoke my entire unicycle with blue spokes and black nipples.
Could you elaborate on that? What exactly is it that causes trouble?
Yes, but the difference isn’t huge (0.7mm and 1.5mm), so I hoped to maybe get away with it, even if it isn’t ideal. If I were to build the wheel from scratch, I’d try to source the optimal spoke length, of course.
I hope to someday go the carbon rim route. If/when I do, I will lace the wheel with its original 125mm hub. In other words, the 100mm hub in the former 125mm wheel is just a temporary solution according to my plans. I’d rather not spend more money than necessary…
I don’t like radial runouts either, but on a uni I’m often too slow to note it. And if I’m fast enough to note it, I’m pedalling at such a cadence that the ride is kinda bouncy anyway, so the runout is negligible.
@Hammer, your proposition sounds reasonable to my ears (because it’s what I wanted to hear. I guess ). I think I will order a 100mm hub and then see how much thread is left. Thinking of it, I even have DT Squorx nipples, which have either a longer thread or a different position for the thread (farther away of the hub). So that could/should solve any issues with spoke lengths.
I have aluminium nipples on my latest wheel build (my only wheel build in like 20 years), my Schlumpf wheel. So far no problems - though I’m not particularly heavy and my riding style is anything but wild.
That sucks! Hope I have more luck with my Schlumpf wheel.
I had a 36" Coker with a 125mm hub and put in a 100mm schlumpf FS (street version). I squeezed the frame until it had 100mm without any issue. I used the same spokes, which were much thicker than normal and inserted a nut below every nipple (quiet some weight). 3 layers of tape around this up and down on the inside of the single wall steel rim. The tube did not complain about it during many years.
With exactly that tube, tire, rim I created @Setonix ultimate wheel, so it is still a working tube.
So on a single wall steel rim I had no problems with spokes being 4mm-5mm too long. Even though the nipples were not as easy to reach from outside for truing anymore.
This was very confusing for me until I realized that you weren’t considering going from 125 to 100 mm crank length, but bearing width But yeah, I totally agree that you should put 100 mm cranks on your 36er, and there is actually no need to do anything at all with your spokes!
If all you described worked well, it’s safe to say that I won’t run in unsurmountable troubles . Worst case would be to use different nipples or use washers. The rim is of the double wall type, so the tube is safe anyway.
No need to squeeze the frame either, since I’ve got one of Jakob’s wonderful Flansberrium steel frames. A true piece of beauty.
Erm, @PedalSprell I don’t know what you were reading, but we’re talking spoke lengths, here! 100mm cranks would be a bit long for a wheel with 100mm spokes. I think cranks in the 2-3cm range would be more suitable. You really should know that.
If you use old spokes that have already been tensioned and then loosen them again, they will stretch as they relax. This can cause your unicycle to creak at the intersections, or you’ll have to remember every position of the spoke where you removed it. Also, if you have an internal disc brake, you have to be careful because the spokes are different lengths by 3mm.
I hope the hollow chamber rim is sufficient for you.
I have a vertical runout of 0.2-0.3 mm and a lateral runout of 0.2 mm. For me, it’s not optimal. So, it’s not within tolerance. Nice is something else for me. Yes, you can break your centering, but I don’t know any other unicyclist who pays as much attention to centering as I do.
My spoke nipples broke after nine years and a lot of truing. Yes, you can use aluminum nipples, but they’re not the optimal solution if you want a very durable unicycle. I said I’d invest the money in good quality so that hopefully I won’t have to touch my wheel again for the next ten years.
Okay, I see you are getting confused about my confusion. I never mentioned 100 mm spoke lengths I just thought you were implying crank lengths and not hub width.
Slighty more on topic: I personally prefer low Q factor. I think switching to 100 mm width would make riding smoother.
Ok. I was pondering about remembering the position of each spoke and build the new wheel exactly the same as the old one - not because I saw a necessity, but because I am like that sometimes. Decided against it, but if it‘s better - why not?
Disc and non-disc side may be different by 3mm, but the disc side is only 1.5mm longer with the 125mm hub than with the 100mm hub, according to the spoke calculator. The difference on the disc side is even smaller.
This I believe. My tolerances are a bit more generous, particularly for a uni.
9 years will do for me. It‘s a trade-off, after all: Less durability, but also less weight for every revolution. That‘s a fair deal in my opinion.
In exceptional cases you might have problems but that’s maybe 2 percent but if it doesn’t bother you then definitely try it. If you want to get a carbon rim at some point then it’s just a temporary solution that will work for you
). I think I will order a 100mm hub and then see how much thread is left. Thinking of it, I even have DT Squorx nipples, which have either a longer thread or a different position for the thread (farther away of the hub). So that could/should solve any issues with spoke lengths. 
But yeah, I totally agree that you should put 100 mm cranks on your 36er, and there is actually no need to do anything at all with your spokes!
. Worst case would be to use different nipples or use washers. The rim is of the double wall type, so the tube is safe anyway.
I just thought you were implying crank lengths and not hub width.