Author Topic: Wheelbuilding myths debunked  (Read 12601 times)

Wheelbuilding myths debunked
« on: September 05, 2011, 08:28:42 pm »
Thought it was about time we had some of these.

1. Spokes do not "bed in" and need retightening after an initial period, unless it's a badly built wheel.

Just occasionally you get a soft hub shell in which the spoke heads can creep a little, but these are rare (the only hub where I had this problem was a very thin Sturmey-Archer alloy shell from 1951, which has flanges the same thickness as the steel shell; they often crack).

2. Spokes do not fail because they are too tight.  They fail because they are too loose (movement leads to fatigue).  The ultimate tensile stress of a spoke is way above anything the rim can take, and riding the wheel makes them go slacker, not tighter.

3. Spoke tension does not affect ride quality.

4. Plain gauge spokes are not stronger than double-butted.  Their advantage is that the wheel goes out of true by a smaller margin should one break, because they are not stretched as far as DB spokes.  But spokes don't break in a good wheel.

5. Radial spoking is not more aerodynamic, but it looks cool.

6. It makes virtually no difference to wheel strength whether your spoking is symmetrical or asymmetrical or which way round the leading and trailing spokes run, unless you have a good reason unconnected to the wheel itself.

 Iif you think your fixie will throw a chain, you want the spokes to throw the chain out, not suck it down between the sprocket and hub flange where it will jam; so the "heads in" spokes should radiate backwards
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Re: Wheelbuilding myths debunked
« Reply #1 on: September 05, 2011, 09:20:45 pm »
Well said, that man!


Kim

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Re: Wheelbuilding myths debunked
« Reply #2 on: September 05, 2011, 09:24:06 pm »
7) Building a wheel doesn't require mystic skills other than patience.  Building a good wheel quickly does.
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Re: Wheelbuilding myths debunked
« Reply #3 on: September 05, 2011, 09:32:49 pm »
I'm not sure what you mean  by 3)

I've had wheels where the spokes were too slack, and when pushing the bike hard (not honking, just going for it), the wheel gave from side to side, making the rear very squirmy in feel.
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Re: Wheelbuilding myths debunked
« Reply #4 on: September 05, 2011, 10:37:59 pm »
I inferred that he means that deliberately building wheels with lower tension in the spokes (as has been suggested to me by someone who should know better), for a touring bike, will give a more comfortable ride. This is not true. I tension my wheels as much as I can (within sensible limits) and fit the biggest tyres I can get in the frame.
If the spokes are slack enough for the bike to squirm, they are too loose, full stop.

corshamjim

Re: Wheelbuilding myths debunked
« Reply #5 on: September 05, 2011, 10:42:03 pm »
I inferred that he means that deliberately building wheels with lower tension in the spokes (as has been suggested to me by someone who should know better),..

That person didn't also advocate tied and soldered spokes perchance ...   ::-)

Woofage

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Re: Wheelbuilding myths debunked
« Reply #6 on: September 05, 2011, 10:54:33 pm »
re 5):
Why is it done then? Just to look cool?

And what's with the low spoke count? Surely the rim needs to be stronger to compensate thereby negating any potential weight saving?
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Rhys W

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Re: Wheelbuilding myths debunked
« Reply #7 on: September 05, 2011, 11:14:49 pm »
Irrelevant. Everybody buys factory wheels these days. If they break, you take them back to the shop and wait 6 weeks, or throw them away.  :demon:

But seriously - tied and soldered spokes don't make a "stronger" wheel, the only advantage is that if a spoke breaks it's less likely to break free completely and cause more damage (to bike or rider).

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Re: Wheelbuilding myths debunked
« Reply #8 on: September 05, 2011, 11:19:34 pm »
The OP is sprinkled with awesome sauce  :thumbsup:
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Re: Wheelbuilding myths debunked
« Reply #9 on: September 05, 2011, 11:26:59 pm »
I inferred that he means that deliberately building wheels with lower tension in the spokes (as has been suggested to me by someone who should know better),..

That person didn't also advocate tied and soldered spokes perchance ...   ::-)

No. I did ask and this person considers that practice to be outmoded.

Re: Wheelbuilding myths debunked
« Reply #10 on: September 05, 2011, 11:28:41 pm »
re 5):
Why is it done then? Just to look cool?

And what's with the low spoke count? Surely the rim needs to be stronger to compensate thereby negating any potential weight saving?

1; Yes.

2; I suspect that this is the case.

Re: Wheelbuilding myths debunked
« Reply #11 on: September 05, 2011, 11:37:34 pm »
re 5):
Why is it done then? Just to look cool?

And what's with the low spoke count? Surely the rim needs to be stronger to compensate thereby negating any potential weight saving?



1; Yes.

2; I suspect that this is the case.

Uncrossed spokes will make a cleaner passage through the air than crossed. As the spokes at the top of a wheel will be travelling somewhat fast than the bike, this may be significant.

Regarding wheel strength: traditionally, low spoke-count wheels were simply more fragile and used mainly in time trials, where a steady speed on reasonable road surfaces wouldn't stress them too much.

Re: Wheelbuilding myths debunked
« Reply #12 on: September 05, 2011, 11:39:49 pm »
I had always thought the reason for radial spokes on front wheels was to save weight (shorter spokes).

Also intrigued by (3).

Woofage

  • Ain't no hooves on my bike.
Re: Wheelbuilding myths debunked
« Reply #13 on: September 05, 2011, 11:42:29 pm »
I had always thought the reason for radial spokes on front wheels was to save weight (shorter spokes).

You are probably right, but radial spoked wheels are usually of the low spoke count so need stronger, heavier rims to compensate. Therefore, it's difficult to compare apples with apples.

Also intrigued by (3).

Me too.
Pen Pusher

Re: Wheelbuilding myths debunked
« Reply #14 on: September 05, 2011, 11:57:31 pm »
I inferred that he means that deliberately building wheels with lower tension in the spokes (as has been suggested to me by someone who should know better),..

That person didn't also advocate tied and soldered spokes perchance ...   ::-)
Nothing wrong with tied and soldered on the rear wheel of a track bike used by a strong sprinter.
<i>Marmite slave</i>

andygates

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Re: Wheelbuilding myths debunked
« Reply #15 on: September 06, 2011, 07:48:09 am »
(6) at last!  Someone else says it!   :thumbsup:

And an extra one: Your first go at a wheel will not kill you.  If it's rideable, it's safe enough, and if it goes out of true, it's not rideable any more. 
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Re: Wheelbuilding myths debunked
« Reply #16 on: September 06, 2011, 08:13:04 am »
8) Having a cup of coffee and a cake at Big Al's does not give you botulism :thumbsup:

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Re: Wheelbuilding myths debunked
« Reply #17 on: September 06, 2011, 08:55:46 am »
re 5):
Why is it done then? Just to look cool?

The spokes can be shorter, therefore a tiny tad lighter and more aero.  Easier to lace as well.  The hub flanges have to be strong enough though, and you lose the undoing-prevention advantage of crossed spokes.  Looking cool is a big part of it.

Quote
And what's with the low spoke count? Surely the rim needs to be stronger to compensate thereby negating any potential weight saving?

Yes, and sometimes the spokes are thicker therefore heavier too.  It is more aerodynamic though.  Weight can be minimised by making the hub incredibly light (which may include stupidly small bearings) and using carbon fibre for the rims.  Some of the fancy low-spoke wheels, especially the cheaper ones, are indeed still heavier than the lightest conventional handbuilt wheels.

Aerodynamics is more important than weight for fast riders.
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Re: Wheelbuilding myths debunked
« Reply #18 on: September 06, 2011, 09:23:34 am »
And an extra one: Your first go at a wheel will not kill you.  If it's rideable, it's safe enough, and if it goes out of true, it's not rideable any more.

+1

When you have a look at the wheels on a lot of low-mid end bikes, it's a miracle that they don't collapse within a few hundred yards. However, they don't. They just mostly work.

You'd have to be seriously ham-fisted to build up a wheel from new parts that was worse than that.

Re: Wheelbuilding myths debunked
« Reply #19 on: September 06, 2011, 10:00:05 am »
Once the tension in the spokes is high enough to hold the wheel in a stable shape, the wheel is already much less flexible than a tyre. When it is fully tensioned, the wheel's flexibility is considerably less than that of the tyre. Wheels should always be tensioned "properly". It is important to choose the components to suit the application, then build the wheel accordingly.

Woofage

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Re: Wheelbuilding myths debunked
« Reply #20 on: September 06, 2011, 10:01:41 am »
Aerodynamics is more important than weight for fast riders.

I'll stick to conventional wheels then ;).
Pen Pusher

Re: Wheelbuilding myths debunked
« Reply #21 on: September 06, 2011, 12:35:45 pm »
Uncrossed spokes will make a cleaner passage through the air than crossed. As the spokes at the top of a wheel will be travelling somewhat fast than the bike, this may be significant.

Will the cleaner passage through the air be noticed at the crossing point (or, for radial spokes, where the crossing point would have been), or through the length of the spoke? Much of the spoke length is already sheltered behind the rim, and there's probably a fair bit of turbulence created by the fork blades. So how much difference is the presence or absence of a crossing point really going to make?

ISTR that something over 90% of the aerodynamic drag experienced by a cyclist is due to the size and riding position of the cyclist, so messing around with spoke counts and crossing patterns seems a little silly.

Biggsy

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Re: Wheelbuilding myths debunked
« Reply #22 on: September 06, 2011, 12:41:03 pm »
It's all silly, but it's satisfying to know that you've done everything possible (within reason and budget) to make the bike as fast as possible - despite the fact that the weeny bit of time saved per mile will only be relevant to time trialists.  It becomes a hobby in itself.

I've also gone to some lengths to save a silly amount of weight - just because it's fun and interesting, to those of us sad enough to find such things fun and interesting.  :)
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Re: Wheelbuilding myths debunked
« Reply #23 on: September 06, 2011, 03:24:02 pm »
I've never understood why, when crossing spokes, some builders pass them "wrong side" of each other so the spokes are touching and curved. This must detract from the overall strength, surely? It looks particularly bad on small wheels.

Re: Wheelbuilding myths debunked
« Reply #24 on: September 06, 2011, 03:28:45 pm »
I've never understood why, when crossing spokes, some builders pass them "wrong side" of each other so the spokes are touching and curved. This must detract from the overall strength, surely? It looks particularly bad on small wheels.

That's the 'lacing' and virtually all good wheels are built that way.