Ok, my 29" Nimbus wheel has been making funny noises when I ride. I want to tighten up the spokes and true up the wheel. I have a spoke tension gauge from Park. Now for the key questions: what tension should I aim for with the wheel? I am not sure who manufactures the rim-UDC? I do not find any advice on spoke tensioning for this rim in particular or for most rims in general. Should I just shoot for 120 kgf? Is that too high or too low? Is there are general guideline for rims?
I have the same question about 36" wheels, which are even less common. How much tension do you want in the spokes? My impression is that more is better–until the rim fails. I would appreciate some numbers from people with experience working on unicycle wheels. (Corbin?)
This is totally non-intuitive, but if spoke tension is even, and if it’s not low enough that any spokes go slack during use, then spoke tension makes NO difference in wheel stiffness. This is on the authority of machine testing and the theory of Jobst Brandt.
Thank you for the reply. I know that the tension should be even. My impression is high tension is better than low tension. The problem is that very high tension is reported to lead to rim failure. Someone posted a nice potato-chip (“potato crisp” for the UK crowd) shaped wheel that looks like it had this problem. I am looking for some guidelines for limits on the tension.
I have built many (over a hundred and then some) bicycle wheels, and now a couple of uni wheels. Tension should be even. The actual tension is probably not that important once the rim is straight, round, and centered between the bearings/lock nuts. If the wheel is over tensioned it can be very hard to true, or maintain later. If you find that you are truing your wheel often it most likely needs more tension.
When tensioning a wheel it is important that you do it incrementally and in many revolutions. If you simply tighten the nippels sequentially around the wheel it can cause the wheel to get too tight before you realize it.
I use the 3x3 method. Starting at the valve stem you give a quarter turn, and then count three spokes and tighten a quarter turn, and so on around the wheel. When you get back to the valve stem you start with the second spoke from the valve stem and continue the same way, and on the third pass you start with the third spoke from the valve stem. After three revolutions of the wheel you will have tightened all of the spokes in the wheel. If you do it right you will have to repeat this a few times to get good tension.
I’ll have to look up what tension I used…I can’t recall what it is off the top of my head. I didn’t use 120 kgf for my wheel, but something lower.
My last 36er wheel build was my first that I built all by myself (I bought the same park tool tension gauge – it works great!). Prior to that, I had the help of Ken Adelman or Bronson Silva ( http://silvacycles.com ) – both of which are experts at building wheels, and taught me how to properly build them.
I wish i knew what tension you should use, but my point in the earlier post is that higher is not necessarily better. Beyond a certain point (the point at which none of the spokes ever go slack while you’re riding), you’re just asking for equipment failure and strangely, not stiffening the wheel AT ALL.
Anyway. Hope I’m not just repeating myself unnecesarily.
My understanding was that if your bottom spokes go slack when just riding around your spoke tension is too low. If you release all the stress on your spokes whenever you are rolling over them you are just asking for them to break at the elbow due to the repeated tensioning and untensioning.
A high tension wheel is definitely stiffer but may fail easier from an impact since the parts are closer to their breaking points.
So a tight wheel should last longer and be stiffer while a softer build can resist impacts better but will have greater chance of metal fatigue failures.
I don’t think there’s anything wrong with a high-tension wheel, and I’ve never seen a high-tension wheel fail from impact in a way that a lower-tension wheel would survive. The only failure I’ve personally seen from high tension is a hub flange failure on a two-cross wheel. For three-cross or four-cross wheels, that shouldn’t be a problem.
A couple years ago I hit a pot hole while riding my 27" uni with a skinny tire. three spokes snapped at the elbow and two broke at the nipple. I built the wheel really tight but the spokes and nipples were re-used and probably 30 years old.
New modern spokes probably would have been fine but those old ones were unable to take the sudden jolt. Not sure what the damage would have been if the spokes were a bit looser, probably more rim damage and less spoke breakage.
Generally I build my wheels pretty tight and think that most bike/unicycle wheels could use a bit of tightening. My 36er sure needed it when i got it.
I just replaced a spoke today. It’s on my 2006 KH 29’’. I can’t quite figure out why. The bike shop guys thinks that I will eventually have to replace all the spokes because their not stainless steel. I have now replaced 7 spokes through the last couple years. I see rusty spots on the spoke crossings. But Don’t fix it until it breaks.
But I tighten the spokes by sound. I like to hear a slightly high pitch(ping). Then I like the spokes to all the same sound. I would be better at it, if I wasn’t tone deaf.
What musical note is the best tension? doo ray me far so la tea doo?
I found a article on tensioning by key years ago. fatter spokes and longer spokes will make a lower pitched sound than skinner or shorter spokes at the same tension. I have no idea what note you should be aiming for but evenness is the most important factor.
So, a bike shop guy says stainless is stronger. The understanding used to be that the strongest wheels were built with galvanized spokes. Stainless ones were prettier, and didn’t rust, but weaker.
We even had DT galvanized spokes back then. Maybe the alloys they are using are better now.
At UBI they teach 100 kgf for non disc wheels, and 110kgf for disc brake wheels, due to the large rotational forces of a disc brake. Personally for my uni I shoot for 110ish. You aren’t necessarily doing yourself too many favours going above that, because eventually the rim will fail.
Thank you for the specific answer. 110 kgf sounds like a reasonable number.
I thought unicycle wheels might be hire tension because they have stronger rims to support the tension. From my reading I had thought that most all of the strength in a bike wheel came from the tension. I am also a bit confused why some unicycle wheels use 13 and 12 Gauge spokes if they are not being tensioned any more than a normal 14 (or smaller) gauge bike spoke.
Strength comes from proper tension, evenly distributed through the spokes. If spokes are loose they break becasue they flex, typically at the elbow. Too much tension- there is no exact number because it depends on the rim quality and design- and you will warp the rim and cause the wheel to become unstable.
Higher gauge spokes are stronger, simply because they are thicker, however, if they are simple straight gauge spokes, you can’t get the same responsive build out of them as a double butted(DD) or triple butted (3D) spoke. Butted spokes place thicker material in elbow and the threads, where a spoke is most prone to breakage, while still allowing a thinner section in the middle so the spoke can stretch and rebound, keeping the wheel active so it can absorb impacts.
If you want to know more about spoked wheels and all the theory behind them, The Art of Wheelbuilding by Gerd Schraner, or The Bicycle Wheel by Jobst Brandt are great resources.
I would appreciate some numbers from people with experience working on unicycle wheels. (Corbin?)