mattkime

I recently bought a Park Tool TM-1 Spoke Tension meter. I was surprised to see that I needed to know the diameter of my spokes. I have a 2002 Schwinn S-30 mountain bike.

Does anyone know the likely diameter of my spokes? I'm certain that they're steel.

kenhill3

Somehow, you are gonna hafta measure them using a caliper or, more accurately, with a micrometer. 1.8mm = 15gauge , 2.0mm = 14gauge. A tension meter measures sideways deflection in the spoke. With 14ga. and 15ga. spokes of EQUAL (proper) tension, the deflection of the (thinner) 15ga. spoke will be greater by virtue of it's being thinner. Perhaps some more experienced wrenches can chime in here.

BTW- What are you doing with a tension meter? :O)

well biked

Did your TM-1 not come with a gauge to measure the spoke diameter? I just bought a TM-1, it came with instructions, a card with the conversion table on it for figuring the tension of various sizes and types of spokes, and a handy metal gauge to measure spoke diameter-

Wil Davis

Here's a picture of the chart & the spoke gauge:

Retro Grouch 

Your bike almost certainly has 14 ga spokes.

cascade168

+1 on the "handy metal gauge". If you did not get one, you should contact your supplier, or Park, and obtain one. Calipers will (obviously) do the job, but that little gauge is nice to have.

If you go to this page:

https://www.parktool.com/products/doc...6428_84698.pdf

the gauge is item #20 (Park part #1059)

mattkime

you're right, i'm missing the diameter gauge and chart.

smurf hunter

The chart is arguably more valuable, as you need to know if the spoke(s) are within range for the given diameter and material.

Wil Davis

If you still have the original box, check to see that the chart is not in the very bottom.

- Wil

blamp28

The chart is downloadable at the Park tool website.

cascade168

Here it is:

https://www.parktool.com/products/doc...05912_4301.pdf

But ...

without a determination of the spoke gauge & type, the chart is of no use whatsoever.

cascade168

Seriously, the folks at Park are excellent with respect to customer service.

Just send them mail at: info@parktool.com

I'll bet they send you the chart and little_gauge/tool_thingy for the asking. Go for it.

AndrewP

Without the chart the tool is useless, because the tool only gives a deflection reading and you need the chart to convert the deflection reading into tension.

mattkime

>> Without the chart the tool is useless, because the tool only gives a deflection reading and you need the chart to convert the deflection reading into tension.

Yes, I figured out so much. The chart is online although I still needed the gauge for spoke thickness. I called park tool and they're sending me one.

DannoXYZ 

After a while when you've been building wheels for a while, you can just touch a spoke, roll it in your fingers and know exactly what diameter it is.

shinyballs

can the Park Tool TM-1 work with 12 gauge spokes?

Soil_Sampler

Are you working on a 36" "Monster Cruiser" wheel?

You could use it to get the spoke tension even, but no way to
calculate 12ga. tension on the chart.

kenhill3

Use the chart to develop an extrapolation based on cross sectional area. :0)

shinyballs

I'm thinking of using it for my 36h 26in mtb wheel on an electric hub motor. Seems like the spoke gets loose when I hit a bump. Hopefully this meter will make the tension all even.

NWsushi

Actually the gauge system is not reliable way to measure spoke diameter (from what I hear there are number of gauge system that measures wires differently). I think the tension meter chart ,and the little tool included to measure spoke diameter, references spoke diameter in millimeter (mm).

DOS

Not necessarily. If they are butted, they would likley be 14 ga on the ends, but something different in the middle, which is what counts when measuring tension.

To OP, Assuming they are pretty standard spokes, until you get the gauge, here is a way to guesstimate the diameter using your eyes and hands:

1. If you can see easily that the last inch or so of the spoke on each end is thicker than the middle section, then you most likely have double butted spokes that are 2mm on the ends and 1.7mm in the middle. Use the column on the chart for 1.7mm spokes

2. If visually, the change in thisckness is not obvious, run you fingers slowly along the spoke, as you near the end, if you can feel the change in thisckness, then you likely have double butted spokes that are 2.0mm on the ends and 1.8mm in the middle. Use values from the chart for 1.8mm spokes

3. If the spoke thickness feels uniform from end to end, probably you have 2mm straight gauge spokes.

DaJMasta

I would have originally assumed 2.0 millimeter, but it seems that earlier models of this bike used 1.8mm straight spokes too, so it's difficult to say.

Without a caliper, you can use a more tedious method:

Cut a 1"x1/4" strip of paper (doesn't have to be exact)
coil it around the spoke, then unravel it so that the end coiled under just barely meets the strip coming around (fully encircling the spoke) and mark it with a sharpened pencil.
Take that sheet and measure the circumference of the spoke by measuring from the edge of the paper to the line.

If it's almost exactly 7mm, then you have a 2.0mm spoke. If it's under 6mm, you have a 1.8mm spoke.

It's not terribly accurate, so it may be worth repeating a couple of times, but the difference is significant enough that with a sharp pencil and a decent ruler you should be able to figure it out.

operator

All this info would've probably been useful 2 years ago guys.

DOS

doh!