Wednesday, July 20, 2011

Tension Adjustments On Tubeless Wheels

I recently heard from some readers across the pond at Strada Hand Built Wheels. They wrote me the following:

Hi Jason

We have just built our first pair of wheels using the NoTubes ZTR Alpha. We
had some issues getting the tension right as when the tyre air pressure is increased to riding levels the spoke tension drops away as it compresses the rim. Increasing the tension further just stretches the alloy round the spokes holes.... Any advice on building with these or can you refer us to anyone with experience please?

Kind regards,


Jonathan


Jonathan Day

Web: Strada Hand Built Wheels

Not having noticed such a problem, I forwarded his comments to Velonews's esteemed technical editor and tubeless expert, Lennard Zinn. He was kind enough to reply:

I haven't checked spoke tension on the A340s since putting road tires on them. At 28psi with 'cross tires it wasn't an issue.But yes, we always notice a decrease in spoke tension with tire inflation. Eaton, for instance, builds the rear wheels off dish so that when the tire is inflated the dish is correct.


Lennard Zinn

Eventually, I heard back from Jonathan over at Strada:

Here are photos [above] from recent builds including these ZTR Alpha rims onto our own label hubs. These were built for a light climber who wanted to try a tubeless setup. He completed the Marmotte 2011 on them which is great. Getting the spoke tension right is tricky and we have decided to sell them only with a new pair of Hutchinson Fusion 3 tyres fitted so we can tune them with the tyres on to ensure the best finish.
Conclusions

To be honest, I still don't know what to make of the whole spoke tension issue. I have now converted at least eight different road wheels to tubeless over the last five years, but none of them have had any spoke tension issues. I have a Park Tools professional truing stand at home, and I like to keep my wheels true within a fraction of a millimeter, so I think I would notice if it screwed up any of my wheels. That said, I trust experts mechanics like Lennard Zinn and professional wheel builders like Jonathan at Strada. If they say it is happening, I believe them. Fortunately, it does seem that this problem, where it arises, is surmountable.

3 comments:

  1. Same issues with the same setup: 30% tension drop with Fusion 3. Using DT and Centrimaster tensiometers. Same issues with ZTR Crest 29" + Schwalbe RoRo TLR: 25% tension drop. Testing with normal clinchers gave a "normal" 8-10% drop. I understand why Strada goes this way and I tend to do the same. Notubes spoke tension recommendations are on the safe side anyway.

    Kind regards, Marc - WheelTec Netherlands

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  2. This looks so good! I'm going to try it.
    Wheels For Sale

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  3. I don't believe this is a 'tubeless' issue, so much as an Alpha340 issue. I've also experienced the same thing (three wheels), and the tension changes significantly even between a standard tire/tube and tubeless (i had to run a tube for a few weeks on a new wheel, waiting for a tire. When i swapped over the tubeless, it went all out of whack again.)

    Unfortunately, i can't recommend the Stans any more, i've also had some significant grief - i had a 24h laced to a PowerTap, and the spoke nipples were literally bursting out of the rim after ~4mos use. They said 'use a 32h', and low-and-behold, my 32h (also laced to a PowerTap) also had the same issue (that was about 9mos of use). I'm 165lbs, and this was on the road, and our roads are pretty good on Vancouver Island, so they weren't 'abused'.

    I'm wondering if you'd be interested in doing a post asking about rims that have been successfully converted? I'm going to stay away from the Stans for the 32h, and get something a little more robust. Unfortunately, it's my understanding OpenPro's don't convert well, so i'm not sure what to get...

    Same with the 24h PowerTap..it's more of a race wheel, and i'd like an aero rim for it, but i'm not sure what is friendly with a tubeless set-up..?

    Would love to see an RFI post on this. =)

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