Vision Metron 40s: spoke tension even overall but way above spec?

[ManekiNico]

I just measured the spoke tension on my 3-year-old Metron 40s and either I'm doing it wrong or Vision's specs are … incorrect?

For example, spoke tension on the front wheel averages 130 kgf. Vision's user manual recommends 80–100 kgf. That's quite the difference.

I'm using Park Tool's tension meter and wheel tension app for calculations. Front wheel has 18 straight-pull, bladed spokes, laced radially. Spokes are ~1.1 mm thick, 2.0 mm wide. Measurements taken without tube/tire mounted. Tension drops with tire inflated to 100 PSI, but not substantially and is still above 100 kgf on average.

Vision is vague on the spokes used, calling them "AE-14" (aero edge 14 gauge). Initial reviews/articles mentioned Sapim CX-Ray spokes, but I doubt that's what's been used. Judging by the "A" imprinted on the spoke heads, I'm guessing they're actually Alpina Flat DB 1.7 spokes.

So, keep the spoke tension as is or try to bring it within spec? Thoughts?

[Marin]

Most tension meters are useless for measuring absolute tension. Did you calibrate the meter, and does the measurement work independent of spoke type?

[joejack951]

How did you measure the spoke thickness? A little error in your measurement can lead to a big difference in actual tension. Another source of error could be variation in spoke thickness and the elliptical profile. For example, Sapim claims 0.9mm thickness for CX Rays but all of mine measure 0.95-1mm.

[F45]

When calibrating my Park TM-1, I've found around 100kgf the actual starts deviating from the chart. I'd estimate you're at 110kgf actual. No worries.

But below 100kgf it has been spot on for aerolites, race, laser, and leader.

[ManekiNico]

Most tension meters are useless for measuring absolute tension.

Good point about absolute vs relative tension. Seems obvious now that you mention it. I didn't calibrate the tension meter and any calibration rig I could put together would be approximate at best. I do have other wheels (bladed and round spokes) but no tension values for any of them so no way of knowing if the meter is any more accurate there.

How did you measure the spoke thickness?

I don't have a micrometer and can't get an accurate reading with callipers, so I'm relying on the published dimensions for the Alpina spokes (2,0 mm wide, 1,05–1,15 mm thick). I think actual width and thickness are a little less than quoted, and have tried playing with the numbers in Park's wheel tension app, but I still get absolute tension values that are above – if closer to – what Vision states.

Thanks for the comments everyone (you too, F45). Since I'm barely competent at wheel truing to begin with, it's probably best I stick to measuring relative tension and keep from making wholesale changes to how my wheels are built.

[gvnfnc77]

I just measured the spoke tension on my 3-year-old Metron 40s and either I'm doing it wrong or Vision's specs are … incorrect?

For example, spoke tension on the front wheel averages 130 kgf. Vision's user manual recommends 80–100 kgf. That's quite the difference.

I'm using Park Tool's tension meter and wheel tension app for calculations. Front wheel has 18 straight-pull, bladed spokes, laced radially. Spokes are ~1.1 mm thick, 2.0 mm wide. Measurements taken without tube/tire mounted. Tension drops with tire inflated to 100 PSI, but not substantially and is still above 100 kgf on average.

Vision is vague on the spokes used, calling them "AE-14" (aero edge 14 gauge). Initial reviews/articles mentioned Sapim CX-Ray spokes, but I doubt that's what's been used. Judging by the "A" imprinted on the spoke heads, I'm guessing they're actually Alpina Flat DB 1.7 spokes.

So, keep the spoke tension as is or try to bring it within spec? Thoughts?

I noticed just today the same thing here on my Vision Metron 55. I also have other 2 pairs of Vision Wheelset, Trimax 30 and t30, same steel blade "Sapim" spokes on board, same situation occurred on Metron 55, drive side on the rear wheel is on TM-1 near 24/25, non drive side and front wheel are about 22/23 on TM-1.

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[whosatthewheel]

If you are using a Park tool meter, this thread is a non starter. The calibration on those is very loose and you can take any value as a plus or minus 25%. Properly calibrated tension meters are significantly more spendy (DT, Sapim, Pillar etc.). You can, however, build a calibration jig for your Park meter.

[gvnfnc77]

If you are using a Park tool meter, this thread is a non starter. The calibration on those is very loose and you can take any value as a plus or minus 25%. Properly calibrated tension meters are significantly more spendy (DT, Sapim, Pillar etc.). You can, however, build a calibration jig for your Park meter.

You're right. I checked my other Vision wheelset (Trimax 30, same steel blade spokes) and i take that as reference for future maintenance on other wheels like the Metron's. Value on the TM-1 are the same by default, i attached pictures.

Front wheel (and rear non drive side): https://imgur.com/a/u03qN
Rear wheel (drive side): https://imgur.com/a/XFSak

[Orlok]

If you are using a Park tool meter, this thread is a non starter. The calibration on those is very loose and you can take any value as a plus or minus 25%. Properly calibrated tension meters are significantly more spendy (DT, Sapim, Pillar etc.). You can, however, build a calibration jig for your Park meter.

You're right. I checked my other Vision wheelset (Trimax 30, same steel blade spokes) and i take that as reference for future maintenance on other wheels like the Metron's. Value on the TM-1 are the same by default, i attached pictures.

Front wheel (and rear non drive side): https://imgur.com/a/u03qN
Rear wheel (drive side): https://imgur.com/a/XFSak

I believe that isn't the right way to take spoke tension on blade spokes.!

[gvnfnc77]

If you are using a Park tool meter, this thread is a non starter. The calibration on those is very loose and you can take any value as a plus or minus 25%. Properly calibrated tension meters are significantly more spendy (DT, Sapim, Pillar etc.). You can, however, build a calibration jig for your Park meter.

You're right. I checked my other Vision wheelset (Trimax 30, same steel blade spokes) and i take that as reference for future maintenance on other wheels like the Metron's. Value on the TM-1 are the same by default, i attached pictures.

Front wheel (and rear non drive side): https://imgur.com/a/u03qN
Rear wheel (drive side): https://imgur.com/a/XFSak

I believe that isn't the right way to take spoke tension on blade spokes.!

Give solutions.

[mattr]

Yeah, you're also measuring the load needed to twist the spoke over quite a short span.

Should be measuring through the flat faces, rather than edge to edge, or your readings will be hugely high.

[gvnfnc77]

Yeah, you're also measuring the load needed to twist the spoke over quite a short span.

Should be measuring through the flat faces, rather than edge to edge, or your readings will be hugely high.

Do you mean this way? https://imgur.com/a/ZHxL2

[gvnfnc77]

Yeah, you're also measuring the load needed to twist the spoke over quite a short span.

Should be measuring through the flat faces, rather than edge to edge, or your readings will be hugely high.

Whit his way the result is...hugely low btw :-/

https://imgur.com/a/OIXfL

[Orlok]

Yeah, you're also measuring the load needed to twist the spoke over quite a short span.

Should be measuring through the flat faces, rather than edge to edge, or your readings will be hugely high.

Do you mean this way? https://imgur.com/a/ZHxL2

Yes, this is the right way to mesure spoke tension on blade spokes.

[Orlok]

Yeah, you're also measuring the load needed to twist the spoke over quite a short span.

Should be measuring through the flat faces, rather than edge to edge, or your readings will be hugely high.

Whit his way the result is...hugely low btw :-/

https://imgur.com/a/OIXfL

No tension at all.? What is the size of the blade sides and metal of the spokes that are mounted.? When you look at the conversion table livered with the Park Tool you can see the tension in kgf ( 1kgf is 10Nm).

For your front wheel (Vision manual 80-100 kgf) it must be ( spoke metal 1,1 x 2 ) 104 kgf = <15 on the Parktool.