The curse of snapping spokes

[vernon levy]

For the second weekend in a row I have managed to snap spokes in the rear
wheel of my road bike.

The first time, I could link the sanpping to hitting a pot hole the dul ping
as the spoke head snapped off at the hub coincided with the impact.

Having had the spok replaced and the wheel trued, a spoke snapped within 25
miles. Pot holes were studiously avoided and there wer no significant
jarring loads on the wheel prior to the second spoke failure.
Is this just bad luck or should I consider having the wheel re-laced with
heavier gauge spokes?
I am still a porky 20 stone the wheel has a Shimano Sora hub and a Rigida
rim if that is any help.

[Tony Raven]

vernon levy wrote:
> For the second weekend in a row I have managed to snap spokes in the rear
> wheel of my road bike.
>
> The first time, I could link the sanpping to hitting a pot hole the dul ping
> as the spoke head snapped off at the hub coincided with the impact.
>
> Having had the spok replaced and the wheel trued, a spoke snapped within 25
> miles. Pot holes were studiously avoided and there wer no significant
> jarring loads on the wheel prior to the second spoke failure.
> Is this just bad luck or should I consider having the wheel re-laced with
> heavier gauge spokes?
> I am still a porky 20 stone the wheel has a Shimano Sora hub and a Rigida
> rim if that is any help.

Its a badly built wheel. You don't need heavier gauge spokes, you just need
the ones you have used properly. The problem you have is the spoke tension is
too low and the spokes have not been stress relieved after the wheel was
tensioned. Ask around the local clubs for a good local builder or else spend
the money instead on The Bicycle Wheel by Jobst Brant and a spoke key and do
it properly yourself.

Tony

[Gearóid Ó Laoi/Garry Lee]

Good advice Tony but 20 stone is a lot. I'm big and it's like me touring
carrying more than 5 stone of luggage, which is 70 lb. I've never carried
more than 35, and I was lighter then.
If a rebuild does not solve the problem, he might need a really strong
wheel.

[Just zis Guy, you know?]

On Sun, 13 Jun 2004 22:24:03 +0100, "Gearóid Ó Laoi/Garry Lee"
> wrote in message >:

>Good advice Tony but 20 stone is a lot.

All the same, a hand tensioned wheel should be strong enough. I know
people who ride tandems with 36 spoke wheels,

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

[Tony Raven]

Gearóid Ó Laoi/Garry Lee wrote:
> Good advice Tony but 20 stone is a lot. I'm big and it's like me touring
> carrying more than 5 stone of luggage, which is 70 lb. I've never carried
> more than 35, and I was lighter then.
> If a rebuild does not solve the problem, he might need a really strong
> wheel.

I'm four stone lighter and ride 36 spoke wheels on some quite rocky off-road
which gives them a pounding they will never see on road plus I ride 40 spoke
wheels on touring tandems with luggage for two, two people and only two wheels
to carry all that weight with only 10% more spokes. A standard 36 spoke wheel
will do fine for 20 stone if properly built.

Tony

[vernon levy]

>
> >Good advice Tony but 20 stone is a lot.

But I'm a light twenty stone :-)
>
> All the same, a hand tensioned wheel should be strong enough. I know
> people who ride tandems with 36 spoke wheels,
>
When I took the wheel in the first time, I asked about heavier gauge spokes
and the LBS reckoned that heavier gauge spokes should not be necessary. The
tension on the spokes after repair was noticeably higher. I'll ask again
when I take the wheel in tomorrow.

None of my other bikes have had this problem. I've only done 250 miles on
the road bike. Perhaps it's the highly strung nature of such beasts. :-)

BTW

what is the going rate for a rebuild?

cheers

Vernon in Leeds

[Clive George]

"Tony Raven" > wrote in message
...

> I'm four stone lighter and ride 36 spoke wheels on some quite rocky
off-road
> which gives them a pounding they will never see on road plus I ride 40
spoke
> wheels on touring tandems with luggage for two, two people and only two
wheels
> to carry all that weight with only 10% more spokes. A standard 36 spoke
wheel
> will do fine for 20 stone if properly built.

Wheel size makes a difference in all of this - Vernon is talking about
700's, your mtb rims are 26" and have big fat tyres to cushion the pounding.

But our tandem wheels (on + off road) are all 36 spoke/26", and I agree with
you really - Vernon just needs his wheels building properly.

cheers,
clive

[Pete Biggs]

Tony Raven wrote:
> Its a badly built wheel. You don't need heavier gauge spokes, you
> just need the ones you have used properly. The problem you have is
> the spoke tension is too low and the spokes have not been stress
> relieved after the wheel was tensioned.

1. The wheel probably was built poorly, but still, some spokes are better
than others and it's sensible for heavier riders to use better than
average spokes.

2. Jobst Brandt claimed low tension does not increase fatigue when I
mentioned the subject on rec.bicycles.tech. So probably lack of stress
relieving and/or inadequate spoke type/number is responsible for Vernon's
problems rather than low/uneven tension (which is more relevant to general
strength and ability to stay true).

~PB

[Pete Biggs]

vernon levy wrote:
> For the second weekend in a row I have managed to snap spokes in the
> rear wheel of my road bike.
>
> The first time, I could link the sanpping to hitting a pot hole the
> dul ping as the spoke head snapped off at the hub coincided with the
> impact.

The pothole was only the final straw. The spoke will have been fatiguing
all the while before that.

> Having had the spok replaced and the wheel trued, a spoke snapped
> within 25 miles. Pot holes were studiously avoided and there wer no
> significant jarring loads on the wheel prior to the second spoke
> failure. Is this just bad luck or should I consider having the wheel
> re-laced with heavier gauge spokes?
> I am still a porky 20 stone the wheel has a Shimano Sora hub and a
> Rigida rim if that is any help.

You may not /need/ better spokes (I don't know what you've got) but DT
Alpine III (2.3/1.8/2.0) should be ideal if you do ever respoke the wheel
or get a new wheel. Also consider switching to a 36-spoke rear wheel if
you have a 32 now. It's important that the spokes are properly stress
relieved*. Not all builders do this, unfortunately.

* http://draco.acs.uci.edu/rbfaq/FAQ/8c.1.html

~PB

[Sandy Morton]

In article >, "Just zis
Guy, you know?" > wrote:
> All the same, a hand tensioned wheel should be strong enough. I
> know people who ride tandems with 36 spoke wheels,

Our hiring tandems all have heavier gauge spokes and don't cause
problems.

--
A T (Sandy) Morton
on the Bicycle Island
In the Global Village
http://www.millport.net