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>An under-tensioned wheel is safer than an overtensioned one Well...an undertensioned wheel is a recipe for broken spokes. Why not correctly tension a wheel?

>An under-tensioned wheel is safer than an overtensioned one Well...an undertensioned wheel is a recipe for broken spokes. Why not correctly tension a wheel? The correct tension is quite a lot higher than most builders go. An overtensioned wheel is not very easy to produce, at high tensions truing the wheel becomes super-critical in that tiny changes move the rim absurd amounts, and that is the point to back off.

anthomtb 5y ago
Is it possible for spokes to gain tension while riding? My intuition says no, which would mean erring on the side of more tension would keep you in the correct range over time. I have heard of top level downhillers using minimal spoke tension for better compliance and traction. They also have professional mechanics and piles of wheels to use for a race weekend. Meaning their wheels have to be just reliable enough to hold together for a 4 minute race run.
- jacquesm 5y ago
  Not normally, unless you count the little bit of variation due to different thermal expansion coefficients of rim and spokes but that should not be enough to make a meaningful difference. But they do lose tension over time, so it doesn't hurt to periodically check. That's also a good way to spot cracks in rims, which and do happen especially on bikes that are built once and then used for years.
- jimnotgym 5y ago
  Interesting, I have stood next to a World Cup winning downhiller begging his mechanic to increase tension in his wheels beyond where the mechanic was happy so his wheels would survive longer. He thought this 'compliance' stuff was bs, and he liked that I agreed with him (hence the conversation). This was a couple of years ago mind, but I would be suprised if it had really changed.
  - anthomtb 5y ago
    A few years back Mike Levy from Pinkbike rode Troy Brosnan's bike and made note of how little tension was in the spokes: https://www.pinkbike.com/news/riding-troy-brosnans-world-cup-dh-bike-crankworx-whistler-2018.html https://www.pinkbike.com/news/riding-troy-brosnans-world-cup.... Paul Aston (World Cup pack fill, former Pinkbike journalist) also made note of experimenting with extremely low tension and implied it worked pretty well: https://www.downtimepodcast.com/paul-aston-2021/ https://www.downtimepodcast.com/paul-aston-2021/ Really though, where you have the resources to experiment with something like spoke tension, you are likely to end up with a couple outliers.
jacquesm 5y ago
Because this isn't math: an overtensioned wheel will break for sure, and will do so violentely, a properly tensioned wheel (which is a pretty wide range, as long as you keep the tension consistent between all spokes) will do just fine and an undertensioned wheel will eventually go out of true, which is a pretty good sign that something isn't ok. If you keep cycling after that point you only have yourself to blame. Overtensioning is actually pretty easy, and I've seen more than one wheel respoked by novices that were overtensioned to the point that they were simply dangerous (because when one spoke goes the wheel will immediately respond and if you're unlucky it could even break).
- jimnotgym 5y ago
  > Because this isn't math Not quite, but it is engineering. > Overtensioning is actually pretty easy Again what materials are you using? When at optimal tensions in a mtb wheel from mavic, you would already be turning really hard and in danger of damaging the nipples before overtensioning. It really is not that easy if you tensioned the wheel evenly
  - jacquesm 5y ago
    Engineering is to math as ideal lines between points are to sharpie marks, superficially they cover the same concepts but they're not the same. Engineers worth with safety margins (in this case: 40 to 60%), mathematicians work with ideals. Engineers will use math to get to their solutions, and will then back off from that 'perfect' solution to give them a safety margin to take into account excursions into borderline overload, material defects and so on all balanced against costs.

anthomtb 5y ago

Is it possible for spokes to gain tension while riding? My intuition says no, which would mean erring on the side of more tension would keep you in the correct range over time. I have heard of top level downhillers using minimal spoke tension for better compliance and traction. They also have professional mechanics and piles of wheels to use for a race weekend. Meaning their wheels have to be just reliable enough to hold together for a 4 minute race run.

jacquesm 5y ago
Not normally, unless you count the little bit of variation due to different thermal expansion coefficients of rim and spokes but that should not be enough to make a meaningful difference. But they do lose tension over time, so it doesn't hurt to periodically check. That's also a good way to spot cracks in rims, which and do happen especially on bikes that are built once and then used for years.
jimnotgym 5y ago
Interesting, I have stood next to a World Cup winning downhiller begging his mechanic to increase tension in his wheels beyond where the mechanic was happy so his wheels would survive longer. He thought this 'compliance' stuff was bs, and he liked that I agreed with him (hence the conversation). This was a couple of years ago mind, but I would be suprised if it had really changed.
- anthomtb 5y ago
  A few years back Mike Levy from Pinkbike rode Troy Brosnan's bike and made note of how little tension was in the spokes: https://www.pinkbike.com/news/riding-troy-brosnans-world-cup-dh-bike-crankworx-whistler-2018.html https://www.pinkbike.com/news/riding-troy-brosnans-world-cup.... Paul Aston (World Cup pack fill, former Pinkbike journalist) also made note of experimenting with extremely low tension and implied it worked pretty well: https://www.downtimepodcast.com/paul-aston-2021/ https://www.downtimepodcast.com/paul-aston-2021/ Really though, where you have the resources to experiment with something like spoke tension, you are likely to end up with a couple outliers.

jacquesm 5y ago

Because this isn't math: an overtensioned wheel will break for sure, and will do so violentely, a properly tensioned wheel (which is a pretty wide range, as long as you keep the tension consistent between all spokes) will do just fine and an undertensioned wheel will eventually go out of true, which is a pretty good sign that something isn't ok. If you keep cycling after that point you only have yourself to blame. Overtensioning is actually pretty easy, and I've seen more than one wheel respoked by novices that were overtensioned to the point that they were simply dangerous (because when one spoke goes the wheel will immediately respond and if you're unlucky it could even break).

jimnotgym 5y ago
> Because this isn't math Not quite, but it is engineering. > Overtensioning is actually pretty easy Again what materials are you using? When at optimal tensions in a mtb wheel from mavic, you would already be turning really hard and in danger of damaging the nipples before overtensioning. It really is not that easy if you tensioned the wheel evenly
- jacquesm 5y ago
  Engineering is to math as ideal lines between points are to sharpie marks, superficially they cover the same concepts but they're not the same. Engineers worth with safety margins (in this case: 40 to 60%), mathematicians work with ideals. Engineers will use math to get to their solutions, and will then back off from that 'perfect' solution to give them a safety margin to take into account excursions into borderline overload, material defects and so on all balanced against costs.