Bicycle Mechanics - Factory built wheel with low spoke tension, is this normal!
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01-19-10, 02:10 PM
Sorry in advance if this is a bit long winded!..
I've recently bought a Park TM-1 spoke tensioner meter, and have just brought one of my wheel builds up to the about the correct tension (it was a Mavic rim and i've brought it up to about 100kgf, spoke tensioner reading of about 23). It has round steel 2mm spokes.
I have compared this with a bicycle that has a factory built wheel.
My wheel has shiny spokes but the factory build has tarnished alloy appearance – but its gotta be steel right, its 2mm, the gauge provided shows that it is a 2mm spoke, is there 2mm aluminum- the TM-1 Tension Meter Conversion Table doesn't list 2mm aluminum! And a magnet sticks to it ..
The confusing thing for me is that the factory built wheel has a very low spoke tension of about tensioner meter 16.5, which if its steel it makes it under 51 kgf, almost off the park conversion table scale. This wheel hasn't seen many miles.
So i'm wondering why the factory built wheel has such a low spoke tension, is this normal or have I missed something along the way!..
01-19-10, 02:19 PM
Not always but hardly surprising. Seen it before and done what was required.
If it's a real dull finish the spokes may be carbon steel with zinc plating. Often called galvanized spokes. If the magnet sticks to the dull spokes better than it sticks to your shiney stainless spokes then I'd vote for zinc plated carbon steel.
01-19-10, 02:19 PM
Very common for the OEM wheels to be very low tension. Presumably this speeds up the production rate and lowers the cost.
01-19-10, 02:29 PM
Thanks for that!
BCRider its difficult to judge if the magnet sticks to one better than the other, not noticeably from checking just now!...
Any opinions should i bring factory wheel tension up significantly!? or can its cheaper rims take it!..
01-19-10, 02:35 PM
Yes - it should be brought up to proper tension, trued, stressed, trued, etc. Average being about 110Kgf drive-side, 70ish nd-s. Check dishing as well - often.
a safe low, without inflated tire on wheel, is the specs panthers said.
01-19-10, 02:40 PM
On my recent job a front wheel, i brought it up to 100, is a front wheel ok at 100kgf, or should they be lower!?
01-19-10, 02:42 PM
100Kgf is just fine.
01-19-10, 04:41 PM
If the magnet is sticking similarly then the dull looking ones are likely just a rougher finish stainless steel. No biggie. I've seen them both ways. I assume the cheaper wheels use cheaper spokes that likely just use the as drawn finish rather than run them through a polishing operation.
When I bought my wife a new 5200 Trek with Bontrager Race Lite wheels the first thing I did when I got the bike home was to check the wheels with my tension meter and truing stand. The spoke tension was way low and very uneven, brand new out of the box. By the time I got through tensioning, truing, dishing, and stress relieving the wheels it would have been easier to have just built new wheels. And my wheels would have been lighter.
01-19-10, 08:22 PM
I've noticed factory wheels typically are undertensioned by about 50%. Depending upon what kind of rim you have on those wheels, you can bring up the tension significantly for a much, much stronger wheel.
01-19-10, 09:22 PM
So how does one determine how tight to make a wheel? I'm about to embark on this without a tensionometer, but even if I had one I wouldn't know how tight to make it. Is there a table somewhere?
01-19-10, 10:00 PM
^Different types of tensiometers use different scales or numerical equivalents. They usually come with the instrument.
01-20-10, 09:31 AM
In reply to the OP:
For entry and replacement wheels...yes this is normal. Wheels straight from the machine are incomplete wheels that shops are "supposed" to spend about 20 minutes each finishing...most shops don't.
For mid-range to high-end machine built wheels...it varies. The higher you go in the bike hierarchy...the better they usually are because at some point the the manufacturer of the bike and/or wheels has the wheels worked on for approx. 15 minutes by hand in the factory before the wheel is or bike is boxed...
...even then a smart shop pops 'em on a stand just to be sure...
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