Spoke tension and breaking on Enve 45?
on-yer-bike
Posts: 2,974
Ive just changed a broken spoke on the rear DS. Enve recommend 120Kgf but all the other DS spokes were around 146Kgf. I have retrued the wheel and have them at around 129Kgf. All 12 spokes on both sides are now within 5% of each other which they certainly werent before.
Does the fact that the DS spokes are a bit over matter? How accurate is the Park TM-1 tension gauge?
This is the 2nd spoke that's broken the first was NDS near the hub and this one was DS at the nipple. The owner had to ride on the wheel for about 80 miles after the first NDS spoke broke and Im wondering if the wheel should really be completely rebuilt using new spokes and Enve brass nipples? The hubs are DT240 and the wheels were bought ready built from a German online store in Spring.
Does the fact that the DS spokes are a bit over matter? How accurate is the Park TM-1 tension gauge?
This is the 2nd spoke that's broken the first was NDS near the hub and this one was DS at the nipple. The owner had to ride on the wheel for about 80 miles after the first NDS spoke broke and Im wondering if the wheel should really be completely rebuilt using new spokes and Enve brass nipples? The hubs are DT240 and the wheels were bought ready built from a German online store in Spring.
Pegoretti
Colnago
Cervelo
Campagnolo
Colnago
Cervelo
Campagnolo
0
Comments
-
The Park gauge overestimates tension by 20%
So your 146 KgF was probably spot on 120 where it should have been.
They are race wheels, built as light as they can get away with, they are not meant to do tens of thousands of miles...
The strength of a spoked wheel (in terms of how much load can carry per given mileage) is given by the total tension of the spokes and the bracing angle.
If you have 24 spokes you need 25% more tension to achieve the same total tension of a 32 and 33% more tension to achieve the same strength of a 36. Tension is however limited by materials... nipples, hubs and rims can only take as much, before cracking. Spokes can generally take a lot more. Hence more spokes = more strength.
Then there is the bracing angle. The wider the hub or the smaller the wheel (rim ERD) the stronger the wheel. Deep rims build stronger wheels, so you can get away with fewer spokes. However, the DT 240 is a very narrow hub (50 mm flange width or so), so the deep rim effect is cancelled by the narrow flange.
The DT 240 builds well with very deep rims 50-60 mm and above, for anything below it's best to use a wider one.left the forum March 20230 -
Read into this what you will. I just took my TM-1 to my Enve 45 (tub) on Chris King wheelset with CX-Rays; factory-built and bought through a UK online retailer this year.
Front (not particularly even tension): average reading 7 (=62 kgf)
Rear NDS: average reading 3. Yes, really. Too low to be represented on the scale.
Rear DS: average reading 10 = 80kgf.
Despite this, the wheels are round, and true, and stiff enough for me to have no rubbing even in big efforts.
Cross-checking, I get an indicated 20 = 128kgf on the DS of some Kinesis Crosslights (Pillar 2-1.6-2mm round spokes) and 15=131Kgf on the DS of some Zipp 808s, also built with CX-Rays.
That's it for factory-built wheels I have to hand (apart from 2 x Mavic on Zicral and one with carbon spokes, none of which is helpful here). All my other wheels were built by me, so were obviously built with the TM-1 I'm using, but the Zipp & Crosslight results seem to imply it's not broken.
I'm now wondering if I need to strip the tubs off the 45s and retension them...yawn. They're less than nine months old and have done just under 1600k.0 -
Do they all over estimate by 20%? I asked the LBS if they had a DT Swiss gauge so that they could check the tension for me. But they use the Park gauge and and say its fine.The Park gauge overestimates tension by 20%
So your 146 KgF was probably spot on 120 where it should have been.Pegoretti
Colnago
Cervelo
Campagnolo0 -
Do they all over estimate by 20%? I asked the LBS if they had a DT Swiss gauge so that they could check the tension for me. But they use the Park gauge and and say its fine.The Park gauge overestimates tension by 20%
So your 146 KgF was probably spot on 120 where it should have been.
Not all... some only 10 some even 30%.
It's fine for a workshop that does repair, it' not fine for a professionalleft the forum March 20230 -
Do they all over estimate by 20%? I asked the LBS if they had a DT Swiss gauge so that they could check the tension for me. But they use the Park gauge and and say its fine.The Park gauge overestimates tension by 20%
So your 146 KgF was probably spot on 120 where it should have been.
Not all... some only 10 some even 30%.
It's fine for a workshop that does repair, it' not fine for a professional
Ive borrowed a DT Tensio from another LBS because no one there new how to use it. I measured at DT rev at 1.13 which coverts to 850N which converts to 85 kgf. The TM-1 measured 18 which converts to 119kgf. Massive difference! The Tensio wont have been calibrated recently but looks in perfect nick. Am I doing something wrong?Pegoretti
Colnago
Cervelo
Campagnolo0 -
Do they all over estimate by 20%? I asked the LBS if they had a DT Swiss gauge so that they could check the tension for me. But they use the Park gauge and and say its fine.The Park gauge overestimates tension by 20%
So your 146 KgF was probably spot on 120 where it should have been.
Not all... some only 10 some even 30%.
It's fine for a workshop that does repair, it' not fine for a professional
Ive borrowed a DT Tensio from another LBS because no one there new how to use it. I measured at DT rev at 1.13 which coverts to 850N which converts to 85 kgf. The TM-1 measured 18 which converts to 119kgf. Massive difference! The Tensio wont have been calibrated recently but looks in perfect nick. Am I doing something wrong?
It's more than 30% difference, it's not unheard of... these TM tension gauges are good to measure relative tensions, but they are not well calibrated for absolute tensions.
You can screw the bolt at the back to get a closer reading to the real one, but it won't change by muchleft the forum March 20230 -
Its more accurate on a 1.8 mm spoke – 18%. Why bother making them?
Do they all over estimate by 20%? I asked the LBS if they had a DT Swiss gauge so that they could check the tension for me. But they use the Park gauge and and say its fine.The Park gauge overestimates tension by 20%
So your 146 KgF was probably spot on 120 where it should have been.
Not all... some only 10 some even 30%.
It's fine for a workshop that does repair, it' not fine for a professional
Ive borrowed a DT Tensio from another LBS because no one there new how to use it. I measured at DT rev at 1.13 which coverts to 850N which converts to 85 kgf. The TM-1 measured 18 which converts to 119kgf. Massive difference! The Tensio wont have been calibrated recently but looks in perfect nick. Am I doing something wrong?
It's more than 30% difference, it's not unheard of... these TM tension gauges are good to measure relative tensions, but they are not well calibrated for absolute tensions.
You can screw the bolt at the back to get a closer reading to the real one, but it won't change by muchPegoretti
Colnago
Cervelo
Campagnolo0 -
If you calculate the statistical rate constant of electron transfer you would be lucky to get within 2-3 orders of magnitude to the experimental one, so 30% off is not so bad...
left the forum March 20230 -
Also remember h that increasing spoke tension does not make the wheel stiffer. Increasing the spoke tension does mean that a higher side or radial load can be applied before spokes go slack which is a good thing.
While Ugo comments are all true you should not being tensioning a low spoke count wheel more than a higher spoke count wheel. High spoke count wheels generally use rims that are less stiff so a higher spoke count is needed.
The best spoke tension gauge is the new Sapim one. It reads cx rays properly and is nice to hold unlike the dt swiss tensio which is quite easy to fumble and the arms being square are not so nice to hold. Also the dt swiss tension cannot read cx rays on the nds rear.
Saw it at the cycle show and ordered as soon as Sapim showed it me. Easily swayed to buy nice tools.
A good spec for all wheels regardless of spoke count is
Rim brake wheels
Rear ds 1200N (unless the rim specifies a lower limit).
Front 1200N
Disc brake
Rear Ds 1200N
Front NDS 1100N
Stick to that and you won't go wrong.http://www.thecycleclinic.co.uk -wheel building and other stuff.0 -
Lost me there PauloIf you calculate the statistical rate constant of electron transfer you would be lucky to get within 2-3 orders of magnitude to the experimental one, so 30% off is not so bad...Pegoretti
Colnago
Cervelo
Campagnolo0 -
Also remember h that increasing spoke tension does not make the wheel stiffer. Increasing the spoke tension does mean that a higher side or radial load can be applied before spokes go slack which is a good thing.
While Ugo comments are all true you should not being tensioning a low spoke count wheel more than a higher spoke count wheel. High spoke count wheels generally use rims that are less stiff so a higher spoke count is needed.
The best spoke tension gauge is the new Sapim one. It reads cx rays properly and is nice to hold unlike the dt swiss tensio which is quite easy to fumble and the arms being square are not so nice to hold. Also the dt swiss tension cannot read cx rays on the nds rear.
Saw it at the cycle show and ordered as soon as Sapim showed it me. Easily swayed to buy nice tools.
A good spec for all wheels regardless of spoke count is
Rim brake wheels
Rear ds 1200N (unless the rim specifies a lower limit).
Front 1200N
Disc brake
Rear Ds 1200N
Front NDS 1100N
Stick to that and you won't go wrong.
Thats what I was working to but with a gauge that is clearly not fit for purpose. Can the Sapim gauge be used on DT Swiss spokes?Pegoretti
Colnago
Cervelo
Campagnolo0
