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Rebuilding a wheel using mid-80's parts - Allowable Tension?

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Rebuilding a wheel using mid-80's parts - Allowable Tension?

Old 10-03-18, 12:51 PM
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jlaw
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Rebuilding a wheel using mid-80's parts - Allowable Tension?

I am rehabbing a 1984 Trek 620. The rear wheel came with a Helicomatic hub that I am replacing with a similar vintage Maillard hub (that has normal 1/4" bearings). Both hubs have identical dimensions so I am going to re-build the wheel using the original 27" rim, spokes, and nipples - but with the Maillard hub substituting for the Helicomatic.

My question is - can I safely tension these 2.0 mm straight gauge spokes to a range of 100-120 kgf using this rim?

The rim is a 'Matrix Anodic T' heat-treated 36 hole rim that is probably original to the bike. It is flat and without obvious defect or serious rust.

Thanks.



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Old 10-03-18, 12:57 PM
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You may be able to build up the tension to that point, but you also probably don't need to, especially if it's a 36 spoke wheel.

​​​​ you should also reuse the spokes and exactly the same orientation. So drive side leading spokes on the old Hub should be drive side leading spokes on the new hub.

I think it's the spoke wires will handle 100 just fine. And if they're Rim hasn't been subjected to dangerous high spoke tension, the rim can probably handle it fine as well. That said, I wouldn't go much over a hundred. Modern rims are more designed with higher tension and lower spoke accounts. But 36 spoke wheels that were common in the early eighties on prior don't need as much tension.
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Old 10-03-18, 01:46 PM
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Originally Posted by TallRider View Post
You may be able to build up the tension to that point, but you also probably don't need to, especially if it's a 36 spoke wheel.

​​​​ you should also reuse the spokes and exactly the same orientation. So drive side leading spokes on the old Hub should be drive side leading spokes on the new hub.

I think it's the spoke wires will handle 100 just fine. And if they're Rim hasn't been subjected to dangerous high spoke tension, the rim can probably handle it fine as well. That said, I wouldn't go much over a hundred. Modern rims are more designed with higher tension and lower spoke accounts. But 36 spoke wheels that were common in the early eighties on prior don't need as much tension.
Is 90-100 kgf a good target range for this wheel?
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Old 10-03-18, 02:17 PM
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Originally Posted by jlaw View Post
Is 90-100 kgf a good target range for this wheel?
Drive side: yes. The NDS will be 2/3 to 3/4 of that.- you can narrow that target range by measuring the projected angle of the spokes, and using trig to calculate the tension ratio. Side to side the tension has to be equal; from that and with the angles, it is a simple calculation to get the tension ratio.
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Old 10-03-18, 06:16 PM
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Originally Posted by jlaw View Post
Is 90-100 kgf a good target range for this wheel?
Yes, for the drive-side of the rear wheel. As @nfmisso says.
I usually don't worry about the trig when wheelbuilding, I just build the wheel with consistent tension, true and round, and get the drive-side up to a pre-determined max.
I'd feel comfortable building the drive-side spokes consistently to 100 on your wheel, because this will decline a bit once a tire is mounted and inflated.
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Old 10-03-18, 07:05 PM
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Before we had fancy dancy tension gages we would pluck a known wheel and match the spoke's tone on the new wheel. You should have a front wheel that serves as a standard to what the rims can handle (with proof of years of miles). Run up the rear's drive side to be at a bit higher tone then the ft wheel is as a start. The LH side will pluck at a lower tone then the ft does. Andy (trying to sound like Fietsbob)

I would think about 100 kgf would be the upper range for these older parts. Andy
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Old 10-04-18, 06:00 AM
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Originally Posted by Andrew R Stewart View Post
Before we had fancy dancy tension gages we would pluck a known wheel and match the spoke's tone on the new wheel. You should have a front wheel that serves as a standard to what the rims can handle (with proof of years of miles). Run up the rear's drive side to be at a bit higher tone then the ft wheel is as a start. The LH side will pluck at a lower tone then the ft does. Andy (trying to sound like Fietsbob)

I would think about 100 kgf would be the upper range for these older parts. Andy
Good idea re: checking the existing tension on the (35 year old) front wheel.
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Old 10-04-18, 08:48 AM
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Originally Posted by Andrew R Stewart View Post
Andy (trying to sound like Fietsbob)
Is he on vacation again?

Aye, high spoke count wheels don't require absurd tension values.
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Old 10-04-18, 10:30 AM
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Checked the spokes on the front wheel and they are all in a range from 80 to 100 kgf with most around 90. I like these old 36 spoke wheels - substantial and true - trustworthy.

I will use 100 kgf as my drive side target value and the NDS will be whatever it is in order to have true and round.

Thanks.
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