Wheel and arm bent

[Dave Kahn]

On Fri, 28 May 2004 20:59:54 +0000 (UTC), paul
<[email protected]> wrote:

>In article <[email protected]>, [email protected]
>says...
>> They looked at me with disbelief, shrugged and
>> said the only other thing they could do was send it back to Trek for
>> analysis and see what Trek had to say, so I agreed to that.
>>
>IANAL but
>Sale of goods act is your friend. You bought an ATB/MTB whatever, and
>you can therefore reasonably expectg it to cope with 2cm bumbs in the
>road, no matter that it was a droped kerb, nor what angle you hit it at.
>The wheel was NOT fit for purpose, Wheels are meant to be round, yours
>isn't any more, ergo it failed under conditions that could reasonalbe be
>expected to be encountered.

I think it's more likely that the wheel bent from having a sudden
sideways load applied than from hitting the kerb. I don't think
there's any evidence that it wasn't fit for its purpose.

--
Dave...

Get a bicycle. You will not regret it. If you live. - Mark Twain

 

[Pete Biggs]

paul wrote:

> You bought an ATB/MTB whatever, and
> you can therefore reasonably expectg it to cope with 2cm bumbs in the
> road, no matter that it was a droped kerb, nor what angle you hit it
> at.

You might expect the wheel not to buckle as it hits a 2 cm bump what kind
of magic can it have to prevent the rider crashing when he does something
stupid? The wheel could have buckled after the initial impact. The wheel
wasn't responsible for the crash. The crash could have happened with ANY
wheel. You can not reasonably expect an MTB wheel to survive all 20 mph
crashes.

~PB

 

[anonymous coward]

On Fri, 28 May 2004 18:10:03 +0000, Roja Doja wrote:

> "Pete Biggs" <pclemantine{remove_fruit}@biggs.tc> wrote in message
> news:[email protected]...
>> Roja Doja wrote:
>> ..............
>> > I hit the kerb between pavement and road where the pavement ramps
>> > down to the road, so the kerb was not more than 2 or 3 cm high.
>>
>> Can you go back and measure the exact height to check?
>
> As it's just outside, yes! It varies between about 1.5 to 2.5 cm (which
> seems almost nothing kerb-wise)
>
>> > It was at quite an oblique angle (i.e. I went up the kerb almost
>> > parallel to it , not straight at it) and I was doing about 20mph or
>> > less. Should this cause a MTB wheel to fail?

I'm bemused by your accident too. I would have thought you would be more
likely to fall sideways to the left - not over the handlebars.

Two questions: how tightly were you holding the handlebars? And did you
have mudguards fitted?

I wonder whether the kerb could have caused the handlebars to twist
rapidly sideways. If the front wheel was pointing sideways then I can see
how it might have failed. But I still think you would have fallen sideways
before any damage could be done to the bike.

I once had an accident where my front mudguard came loose and caught in
the front wheel. The damage was spectacular even though I was not going
fast - the tyre was bunched up against the mudguard and the valve torn
from the inner tube; the front wheel ended up looking like a pringle. The
bike cartwheeled, landing on (and smashing) the saddle.

As an aside, I was so dazed it took me a few minutes to work out what had
happened. An elderly couple on the other side of the road were
convinced I'd had a seizure and cycled into a lamp-post next to where I
fell. Even though I didn't hit my head I half-believed them for a while.
It must have looked like I cycled into an invisible brick-wall -
interesting how we can make up stories to explain what we see.

>> First of all, regardless of wheel strength, it's really dangerous to go up
>> a kerb at an oblique angle, full stop. You can loose control all too
>> easily, as you've found. Always take any kerbs straight on and at low
>> speed, easing your weight off the wheels.
>
> Easy if you're crossing a road, but I guess if you're coming off a busy
> road, you can't really pull out into the middle of the road so you can turn
> towards the kerb straight-on can you?

Cars turning right often hold up the traffic whilst they're waiting for
the other side of the road to be clear. If you've got to, then do...

Assuming your normal cycling distance is about a meter from the kerb, you
should be able to turn so the front wheel crosses the kerb at 45 degrees
and slow down a bit - which IMO should be fine.

> At least I've never seen anyone attempt that! Perhaps I should've
> pulled over and got off, then lifted the bike onto the pavement, maybe
> if I had a race bike with super skinny wheels I'd have been more
> inclined to do that, but I assumed it wouldn't be a problem riding a
> mountain bike with bit fat tyres, it's never been a problem before. My
> arm tells me I was wrong though!

I'm glad to hear the rest of you survived. I hope you have a speedy
recovery.

>> Note: Wheel can be rebuilt using existing hub and spokes. Don't need
>> a whole new wheel.
>
> Yes, I guess that was what they meant when they talked about a buying a
> new one (new rim?).

It might pay to check the hub before getting the wheel rebuilt. The
flanges (that hold the spokes) might have cracked, and check the axle
moves smoothly.

AC

 

[Paul - xxx]

Simon Brooke posted ...

> in message <[email protected]>, Paul - ***
> ('[email protected]') wrote:
>
>> Roja Doja posted ...
>>
>>> "Simon Proven" wrote:
>>> [snip]
>>>> Dropped kerbs can be badly aligned. You described it being up to
>>>> an inch high, which I reckon's too much for mounting at an oblique
>>>> angle. If meant for cycling up (i.e. you were joining a cycle path
>>>> on the pavement) then I'd consider a complaint to the council.
>>>>
>>>> I wouldn't ever attempt to ride up such a high kerb at 20mph.
>>>
>>> Fair enough, given opinion so far, I forsee I won't be attempting to
>>> ride up dropped kerbs again.
>>>
>>> I don't think I'd like to actually put the bike to its supposed use
>>> then, and ride it down a mountain, if a 1.5cm-2.5cm lip is enough to
>>> cause problems?
>>
>> It's not just the height of the kerb, it's your manner of approach
>> that's
>> part of the problem too. In normal circumstances you can hit rocks
>> etc that are far bigger, but they'll not be quite as solid as a solid
>> thing and will
>> give somewhat. A kerb doesn't give ...
>
> I've just posted links to two photos of the Slab. Believe me, there
> isn't a kerb - there isn't a building - in the whole of Europe as sold
> as that. London Embankment was built with granite from Dalbeattie, but
> the slab has never been cut. It isn't blocks joined together with
> mortar. It's just one solid knobble of the planet's crust. One piece
> of granite, with gnarly big faults in it which run across the only
> track down at about 20 degrees.

Different thing entirely, and normally only used and only recommended for
use by experienced cyclists. This guy's a novice and simply did it wrong ..

> A bike which can't cope with that can't really be sold as a mountain
> bike.

I guess my mates Santa Cruz Heckler isn't a mountain bike then ? His rear
wheel collapsed on similar steps in the Derbyshire hills ... The Trek 3500
the OP is talking about is not a bike marketed and meant for this style of
mountain biking .. it's a £200 'starter' mountain bike. However an
experienced rider would probably easily get it safely down the steps, but a
novice, such as the OP, may easily struggle with a kerb ..

> It is after all, an official government owned, government built,
> government sponsored cycle track: <URL:http://www.7stanes.gov.uk>

That makes it alright to use for anyone then ?

--
Paul

(8(|) Homer rocks ..

 

[Mark South]

"Pete Biggs" <pclemantine{remove_fruit}@biggs.tc> wrote in message
news:[email protected]...

> You could try the rec.bicycles.tech newsgroup. Jobst Brandt, author of
> the world famous The Bicycle Wheel book, will answer with a bit of luck
> (if he's not away on holiday). Plenty of other wheel experts there as
> well. But don't expect any sympathy there: they're a hard bunch!

It's not so much that they are a hard bunch as that the group has dealt with a
lot of the same questions a few thousand times, so posts like "I though about
wheels and it seems to me that the hub hangs from the top spokes really" tend to
get a somewhat short response.

I've only been reading it since 1993 (it's older than that IIRR) and I can't
tell you how many times the "grease/don't grease the crank tapers to install"
argument has been covered
--

-- M.

 

[Mark South]

"anonymous coward" <[email protected]> wrote in message
news[email protected]...

> It might pay to check the hub before getting the wheel rebuilt. The
> flanges (that hold the spokes) might have cracked, and check the axle
> moves smoothly.

While checking the hub is a good idea, the failure mode of collapsing wheels
involves the spokes losing tension, so if there are no snapped spokes the hub
will probably check out fine. In that case, the spokes can probably be re-used
as well.
--

-- M.

 

[Doki]

Pete Biggs wrote:
> paul wrote:
>
>> You bought an ATB/MTB whatever, and
>> you can therefore reasonably expectg it to cope with 2cm bumbs in the
>> road, no matter that it was a droped kerb, nor what angle you hit it
>> at.
>
> You might expect the wheel not to buckle as it hits a 2 cm bump what
> kind of magic can it have to prevent the rider crashing when he does
> something stupid? The wheel could have buckled after the initial
> impact. The wheel wasn't responsible for the crash. The crash could
> have happened with ANY wheel. You can not reasonably expect an MTB
> wheel to survive all 20 mph crashes.

So you mean when I'm bombing down a local lane at 20mph I ought to be
expecting my front wheel to fold up? It's a mountain bike wheel for christ's
sake.

 

[Tony Raven]

Doki wrote:
>
> So you mean when I'm bombing down a local lane at 20mph I ought to be
> expecting my front wheel to fold up? It's a mountain bike wheel for christ's
> sake.

It will if you turn it across your direction of travel too fast which is what
happened here when the wheel caught the kerb obliquely. Try it sometime. Its
in the original Richards Bicycle Book (don't know about the newer versions) as
the quickest way to stop at the expense of wrecking your wheel.

Tony

 

[Mark South]

"Tony Raven" <[email protected]> wrote in message
news:[email protected]...
> Doki wrote:
> >
> > So you mean when I'm bombing down a local lane at 20mph I ought to be
> > expecting my front wheel to fold up? It's a mountain bike wheel for christ's
> > sake.
>
> It will if you turn it across your direction of travel too fast which is what
> happened here when the wheel caught the kerb obliquely. Try it sometime. Its
> in the original Richards Bicycle Book (don't know about the newer versions) as
> the quickest way to stop at the expense of wrecking your wheel.

Having looked up Jobst's estimates in The Book, he says that the lateral
strength of a wheel is about 10% of its axial strength, so a relatively small
sideways load will fold it.

Basically, Sale of Goods or not, bicycle wheels are not designed to take
sideways loads.
--
Mark South: World Citizen, Net Denizen

 

[Simon Brooke]

in message <[email protected]>, Doki
('[email protected]') wrote:

>
>
> Pete Biggs wrote:
>> paul wrote:
>>
>>> You bought an ATB/MTB whatever, and
>>> you can therefore reasonably expectg it to cope with 2cm bumbs in
>>> the road, no matter that it was a droped kerb, nor what angle you
>>> hit it at.
>>
>> You might expect the wheel not to buckle as it hits a 2 cm bump what
>> kind of magic can it have to prevent the rider crashing when he does
>> something stupid? The wheel could have buckled after the initial
>> impact. The wheel wasn't responsible for the crash. The crash could
>> have happened with ANY wheel. You can not reasonably expect an MTB
>> wheel to survive all 20 mph crashes.
>
> So you mean when I'm bombing down a local lane at 20mph I ought to be
> expecting my front wheel to fold up? It's a mountain bike wheel for
> christ's sake.

No. It's virtually impossible to get a bike wheel to fold up by impacts
perpendicular to its axis. It's both incredibly strong and incredibly
springy. That's why I asked if the OP felt the handlebars jerk round -
because, as other people have said, wheels are very much weaker
sideways, so if the impact with the kerb caused a big, sudden steering
deflection that might cause it.

But mountain biking would be impossible if wheels folded up when they
hit a 1 inch bump at twenty miles an hour.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; When all else fails, read the distractions.

 

[Ambrose Nankivell]

In news:[email protected],
Tony Raven <[email protected]> typed:
> Doki wrote:
>>
>> So you mean when I'm bombing down a local lane at 20mph I ought to be
>> expecting my front wheel to fold up? It's a mountain bike wheel for
>> christ's sake.
>
> It will if you turn it across your direction of travel too fast which
> is what happened here when the wheel caught the kerb obliquely. Try
> it sometime. Its in the original Richards Bicycle Book (don't know
> about the newer versions) as the quickest way to stop at the expense
> of wrecking your wheel.

And presumably wrecking your teeth, too. If I were trying to avoid a solid
object I'd rather take my chance on flying into it and stopping my body that
way than collapsing my wheel and launching myself headfirst into the
obstacle.

A

 

[Pete Biggs]

Doki wrote:

>> You might expect the wheel not to buckle as it hits a 2 cm bump what
>> kind of magic can it have to prevent the rider crashing when he does
>> something stupid? The wheel could have buckled after the initial
>> impact. The wheel wasn't responsible for the crash. The crash could
>> have happened with ANY wheel. You can not reasonably expect an MTB
>> wheel to survive all 20 mph crashes.
>
> So you mean when I'm bombing down a local lane at 20mph I ought to be
> expecting my front wheel to fold up? It's a mountain bike wheel for
> christ's sake.

Read what I wrote please. Can't expect it to survive ALL 20 mph CRASHES.
Hitting a 2cm bump doesn't count as a "crash" but hitting it in such a way
that you loose control and go over the handlebars and your bike hits the
road, does. Get it?

~PB

 

[Doki]

Pete Biggs wrote:
> Doki wrote:
>
>>> You might expect the wheel not to buckle as it hits a 2 cm bump what
>>> kind of magic can it have to prevent the rider crashing when he does
>>> something stupid? The wheel could have buckled after the initial
>>> impact. The wheel wasn't responsible for the crash. The crash
>>> could have happened with ANY wheel. You can not reasonably expect
>>> an MTB wheel to survive all 20 mph crashes.
>>
>> So you mean when I'm bombing down a local lane at 20mph I ought to be
>> expecting my front wheel to fold up? It's a mountain bike wheel for
>> christ's sake.
>
> Read what I wrote please. Can't expect it to survive ALL 20 mph
> CRASHES. Hitting a 2cm bump doesn't count as a "crash" but hitting it
> in such a way that you loose control and go over the handlebars and
> your bike hits the road, does. Get it?

Yep. I should have read it rather than skimmed through it before I replied.
I'd expect to be able to ride up kerbs on my tyres (thought at a relatively
steep angle), but I imagine slicks are rather smaller than my MTB tyres.

 

[Tony Raven]

Doki wrote:
>
> Yep. I should have read it rather than skimmed through it before I replied.
> I'd expect to be able to ride up kerbs on my tyres (thought at a relatively
> steep angle), but I imagine slicks are rather smaller than my MTB tyres.

I'm extremely wary of small kerbs at oblique angles - they've caught me out
too often on everything from road bikes to motorbikes. I always make a point
now of crossing them by turning across them.

Tony

 

[psycho.fifer]

I think you must have put your weight on your front wheel during th
crash. The kerb cannot have done this to your wheel from what I hav
read. If the wheel is bent into an s you can bend it back withou
tighening or loosening any spokes. The wheel has warped due to th
weight it has endured laterally. Next time this happens make sure you
tyre is rock hard, take the wheel in both hands and wallop the tyre har
off the ground at the appropriate location(s). The wheel wil
(probably!) spring back into shape and be nearly true. I've done thi
many times and it is a good fix if you're miles from home. Depending o
the wheel you may still need a replacement after this type of action an
I wouldn't recommend it if your riding down a mountain! To my knowledge
there is one other way of bending a wheel into an s and that is t
overtighten the spokes. I am speaking from experience here and with thi
particular wheel all I had to do was loosen all the spokes. Whee
building is good clean fun! I regularly go up larger kerbs on my race
with skinny rims and tyres (700x23C). It is risky at small angles bu
again if you slightly lift your front wheel and then your back whee
using your feet (all cyclist's sould be physically attached to thei
pedals) it's no problem and I've easily done this on my racer at 20mph

Good luck and please don't sue me if anyone injures themselves takin
my advice


-

 

[Roja Doja]

Well, I admit I'm one of those lurkers who never posts anything until it's
in my interest, but I read this group again for the first time since I
posted this 3 months ago and, blimey, my old post is still in my current
newsgroup feed, so thanks for all the responses, and I thought I'd reply to
finish the story.

Resume: Bike shop sent wheel back to Trek. I got a new wheel. No-one's
admitting any blame for anything (fair enough I supopse given our
compensation culture world...). I'm happy (all I wanted was my new bike
back to how it was), I still ride up the same kerb, at the same angle (I
have to, to get home, and it's impractial to approach from any other angle)
though usually more cautiously and at a slower speed now. Arm is fully
recovered. Still cycling to work and back (nearly) every day.

My ride is a bit odd. It's only 2 miles, all up a 15% incline on the way
in, and all "woohoo", on the way back...
I must admit I thought the uphill bit it would get easier with daily
practice, but it doesn't, is this normal???

Roger

"Roja Doja" <[email protected]> wrote in message
news:[email protected]...
> Hello again,
>
> I posted here about a month ago, enquiring about how much I should spend
on
> a new bike. After reading the many helpful responses, I bought a new Trek
> 3500 with semi-slick tyres and was happily riding it to work and back
every
> day.
>
> On Tuesday, I was almost home, cycled off the road onto the pavement near
my
> house, and before I knew it I'd gone over the front and hit the ground,
the
> bike flipped over once and then stopped. When I picked myself and the
bike
> up, I noticed I couldn't push the bike as the wheel was bent quite badly.
> Since the bike didn't hit anything else after I fell off, I can only
assume
> that the wheel must've bent as I hit the kerb, and the bent wheel was what
> caused me to crash (it's a perfectly straight bit of road pavement, not
the
> sort of place where you think anyone could have an accident). In the fall
I
> fractured my radius near the elbow, which is proving to be a considerable
> nuisance!
>
> I hit the kerb between pavement and road where the pavement ramps down to
> the road, so the kerb was not more than 2 or 3 cm high. It was at quite
an
> oblique angle (i.e. I went up the kerb almost parallel to it , not
straight
> at it) and I was doing about 20mph or less. Should this cause a MTB wheel
> to fail?
>
> I took it back to the shop today, expecting sympathy, explanations, a
> replacement wheel and perhaps apologies. I didn't get any of that.
Looking
> at the wheel, they agreed it must've been some sideways force that bent
the
> wheel, as there were no marks on the rim that would've indicated a big
> impact from the front, they looked at it in more detail the workshop, then
> said it was too bent to repair and suggested I buy a new one. I was
pretty
> incensed at this, and suggested that a 3 week old mountain bike wheel
should
> not be expected to fail going over a 3cm kerb at 20 mph, and that as such
it
> wasn't fit for its purpose. They looked at me with disbelief, shrugged
and
> said the only other thing they could do was send it back to Trek for
> analysis and see what Trek had to say, so I agreed to that.
>
> Am I going mad? Assuming you believe I'm telling the truth, and that I
> really didn't ride it into a wall at 50mph or something similary stupid,
> shouldn't a mountain bike wheel take a bit more stick than this? Doesn't
the
> fact that the wheel is badly bent indicate that it's failed? Shouldn't
the
> shop be a bit more sympathetic??
>
> Roger
>
>

 

[Chris Davies]

>
> My ride is a bit odd. It's only 2 miles, all up a 15% incline on the way
> in, and all "woohoo", on the way back...
> I must admit I thought the uphill bit it would get easier with daily
> practice, but it doesn't, is this normal???
>
> Roger

Just get up the hill and don't rush. Think of the "woohoo" on the way
back. Also, more riding will give a faster improvement.

Chris

--
|C|H|R|I|S|@|T|R|I|N|I|T|Y|W|I|L|L|S|.|C|O|M|
Remove the bars to contact me

 

[David Martin]

On 12/8/04 10:28 pm, in article [email protected], "Roja
Doja" <[email protected]> wrote:

> I must admit I thought the uphill bit it would get easier with daily
> practice, but it doesn't, is this normal???

It doesn't get easier, it just gets faster.

...d

 

[Pete Biggs]

Roja Doja wrote:
> Resume: Bike shop sent wheel back to Trek. I got a new wheel.
> No-one's admitting any blame for anything (fair enough I supopse
> given our compensation culture world...). I'm happy (all I wanted
> was my new bike back to how it was), I still ride up the same kerb,
> at the same angle (I have to, to get home, and it's impractial to
> approach from any other angle) though usually more cautiously and at
> a slower speed now. Arm is fully recovered. Still cycling to work
> and back (nearly) every day.

Practice balancing and steering at lower speeds and you'll be able turn in
at a squarer angle. I don't beleive anyone has to ride up a kerb at a
shallow angle (except perhaps for some weird one-off emergency).

~PB

 

[Arthur Clune]

Roja Doja <[email protected]> wrote:

: I must admit I thought the uphill bit it would get easier with daily
: practice, but it doesn't, is this normal???

"It never gets any easier, it just gets faster" - Greg Le Mond

--
Arthur Clune http://www.clune.org
"Technolibertarians make a philosophy out of a personality defect"
- Paulina Borsook