A question on spoke tension
10-16-23, 11:59 AM
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A question on spoke tension
A friend recently obtained this bike and rebuilt a taco-ed rear wheel but wants me to true it. What spoke tension should I be looking at, drive and non drive side according to my Park Tool spoke tensionometer. As always, thank you for your input.
10-16-23, 01:18 PM
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Thread moved from Appraisals to Mechanics.
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10-16-23, 01:34 PM
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Your tensiometer has a guide card. Use the lower end of the tension range for the spoke diameter you're using.
Or just make them reasonably tight and even in tone when plucked. This is not the kind of wheel where the tension is critical
Or just make them reasonably tight and even in tone when plucked. This is not the kind of wheel where the tension is critical
10-16-23, 01:59 PM
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Was the rim bent with the taco? If so, was it bent back? If you have to true a bent rim to be straight, throw the book on spoke tension out the window. You are now just trying to salvage a botched birthday cake that fell in the open. (And that truing job will not be permanent if the bike is actually ridden much.)
At the shop I worked in mid-70s, we had a mechanic who was a master at slamming wheels to remove bends. He'd study the wheel. loosen the spokes around the bend, the slam the wheel on a concrete step. Re-tighten. a little final truing and 4 hours later hand the wheel back to the customer. (Four hours so there was zero chance of the customer seeing the process!) Mechanic fully "got" that a bent wheel had to be bent back to have any chance of being a "happy" wheel later. And bending steel and aluminum isn't a pretty process. Wheels were never perfect after the second bend. The metal would work harden at the beginning and end of the damaged area and resist the bend back. So they would never be "gems" but many went miles and years after the "treatment".
Caution - this approach worked really well for steel and 1970s aluminum rims. In the '80s, aluminum changed to a much stronger but far less forgiving of bends alloy. I only do this on the old stuff.
At the shop I worked in mid-70s, we had a mechanic who was a master at slamming wheels to remove bends. He'd study the wheel. loosen the spokes around the bend, the slam the wheel on a concrete step. Re-tighten. a little final truing and 4 hours later hand the wheel back to the customer. (Four hours so there was zero chance of the customer seeing the process!) Mechanic fully "got" that a bent wheel had to be bent back to have any chance of being a "happy" wheel later. And bending steel and aluminum isn't a pretty process. Wheels were never perfect after the second bend. The metal would work harden at the beginning and end of the damaged area and resist the bend back. So they would never be "gems" but many went miles and years after the "treatment".
Caution - this approach worked really well for steel and 1970s aluminum rims. In the '80s, aluminum changed to a much stronger but far less forgiving of bends alloy. I only do this on the old stuff.
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10-16-23, 03:11 PM
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The RANGE of proper tension is a function of spoke gauge. Assuming these are 16g spokes, that would be anywhere from 60-110kgf.
I'd shoot for mid-range, or 80-90kgf both front and rear. If you want to be fancy, go 70 in front and 90 rear.
I'd shoot for mid-range, or 80-90kgf both front and rear. If you want to be fancy, go 70 in front and 90 rear.
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10-16-23, 03:13 PM
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Was the rim bent with the taco? If so, was it bent back? If you have to true a bent rim to be straight, throw the book on spoke tension out the window. You are now just trying to salvage a botched birthday cake that fell in the open. (And that truing job will not be permanent if the bike is actually ridden much.)
At the shop I worked in mid-70s, we had a mechanic who was a master at slamming wheels to remove bends. He'd study the wheel. loosen the spokes around the bend, the slam the wheel on a concrete step. Re-tighten. a little final truing and 4 hours later hand the wheel back to the customer. (Four hours so there was zero chance of the customer seeing the process!) Mechanic fully "got" that a bent wheel had to be bent back to have any chance of being a "happy" wheel later. And bending steel and aluminum isn't a pretty process. Wheels were never perfect after the second bend. The metal would work harden at the beginning and end of the damaged area and resist the bend back. So they would never be "gems" but many went miles and years after the "treatment".
Caution - this approach worked really well for steel and 1970s aluminum rims. In the '80s, aluminum changed to a much stronger but far less forgiving of bends alloy. I only do this on the old stuff.
At the shop I worked in mid-70s, we had a mechanic who was a master at slamming wheels to remove bends. He'd study the wheel. loosen the spokes around the bend, the slam the wheel on a concrete step. Re-tighten. a little final truing and 4 hours later hand the wheel back to the customer. (Four hours so there was zero chance of the customer seeing the process!) Mechanic fully "got" that a bent wheel had to be bent back to have any chance of being a "happy" wheel later. And bending steel and aluminum isn't a pretty process. Wheels were never perfect after the second bend. The metal would work harden at the beginning and end of the damaged area and resist the bend back. So they would never be "gems" but many went miles and years after the "treatment".
Caution - this approach worked really well for steel and 1970s aluminum rims. In the '80s, aluminum changed to a much stronger but far less forgiving of bends alloy. I only do this on the old stuff.
10-16-23, 05:23 PM
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The spokes are 14 gauge, 2mm. I asked the owner to bring me the front wheel for comparison and those spokes don't even register 0 on the Park Tensionoometer, Ha. Loose as a goose. I'm getting it trued up but the replacement old used beat up rim is a real treat to work on....not.
10-16-23, 06:35 PM
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10-17-23, 11:13 AM
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Assuming the rim is the same type (single wall?), I'd aim for about 90 for the high range.
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