Weird Instability Problem When Putting The Power Down...

Check for a broken chain stay.

"Christopher Harrison" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Hi all,

Just recently my bike has suffered from a weird problem whereby it
will suddenly lurch to the right if you're leaning on that side, when
rocking to-and-fro for leverage (e.g. climbing or sprinting). It means
you have to react by quickly shifting to the left to avoid toppling
over (into the road, as we drive on the left here).

Whenever it happens, it seems to stem from the front wheel -- possibly
the tyre's sidewall. I've taken a look at both wheels and they seem to
be true (as far as I can tell) and there is no damage to either tyre
(700x23) that I can see... I've been told that it could just be that
I'm putting too much power down (i.e. the drive train is on the right
and the increased torque causes the instability). However, it
sometimes happens at low speeds (even when I'm not out of the saddle);
also, whilst it's possible that my power may have increased just
recently, I don't think it would have that significantly!
My only other line of enquiry is checking the stem and handlebars, to
make sure they're even. However, I'm pretty sure they are: I had my
bike serviced and checked-over just a few weeks ago after being hit by
a car. Things couldn't have got out of alignment so soon.

Any advice would be most gratefully received! At the moment, it's kind
of a problem: I'm not confident in riding at normal speed (and
especially not high speed or up a hard climb)...

Many thanks 🙂
Christopher Harrison

Christopher Harrison said:

Just recently my bike has suffered from a weird problem whereby it
will suddenly lurch to the right if you're leaning on that side, when
rocking to-and-fro for leverage (e.g. climbing or sprinting). It means
you have to react by quickly shifting to the left to avoid toppling
over (into the road, as we drive on the left here).

[snip]

Quoted message said:

However, I'm pretty sure they are: I had my
bike serviced and checked-over just a few weeks ago after being hit by
a car. Things couldn't have got out of alignment so soon.

Any advice would be most gratefully received! At the moment, it's kind
of a problem: I'm not confident in riding at normal speed (and
especially not high speed or up a hard climb)...

OK - so your bike was hit by a car and now, only now?, is suffering from
a strange problem. <lol> my guess is they are related.

Sounds like a case of frame or component damage to me. But a *lot* more
details would be required to narrow that down. But I'd carefully inspect
the chainstays and seatstays, and the bottom bracket and see if it might
be cracked. You could also flex things carefully and see if there are
differences between the right and left side while doing so.

*excessive movement of the bike to one side while under power isn't normal*

Regards

Bill

William R. Mattil said:

Christopher Harrison said:

Just recently my bike has suffered from a weird problem whereby it
will suddenly lurch to the right if you're leaning on that side,

Sounds like a case of frame or component damage to me.

Yeah. Could be that the wheels are out of alignment (front fork bent
to the left).

--
E. Dronkert

Thanks guys 🙂

When I had it serviced, after my little accident, they gave it the all-
clear and deemed it road-worthy -- and I trust them on experience...
However, I shall check these things out.

In article <[email hidden]>,

Christopher Harrison said:

Thanks guys 🙂

When I had it serviced, after my little accident, they gave it the all-
clear and deemed it road-worthy -- and I trust them on experience...
However, I shall check these things out.

This is just a shot in the dark, but if everything else checks
out, see if the headset is turning completely freely. Even a
minor bind can cause very strange handling effects.

_ Booker C. Bense

Christopher Harrison said:

Thanks guys 🙂

When I had it serviced, after my little accident, they gave it the all-
clear and deemed it road-worthy -- and I trust them on experience...
However, I shall check these things out.

A good idea.

A couple quick and dirty aligment tests: a) loop a string from one
rear dropout, around the headtube to the opposite dropout, then
measure the clearance on either side of the seattube; b) when riding
no-hands does the bike have a tendency to veer to one side?

In article
<[email hidden]>
,
Christopher Harrison

Quoted message said:

Hi all,

Just recently my bike has suffered from a weird problem whereby it
will suddenly lurch to the right if you're leaning on that side, when
rocking to-and-fro for leverage (e.g. climbing or sprinting). It means
you have to react by quickly shifting to the left to avoid toppling
over (into the road, as we drive on the left here).

Whenever it happens, it seems to stem from the front wheel -- possibly
the tyre's sidewall. I've taken a look at both wheels and they seem to
be true (as far as I can tell) and there is no damage to either tyre
(700x23) that I can see... I've been told that it could just be that
I'm putting too much power down (i.e. the drive train is on the right
and the increased torque causes the instability). However, it
sometimes happens at low speeds (even when I'm not out of the saddle);
also, whilst it's possible that my power may have increased just
recently, I don't think it would have that significantly!
My only other line of enquiry is checking the stem and handlebars, to
make sure they're even. However, I'm pretty sure they are: I had my
bike serviced and checked-over just a few weeks ago after being hit by
a car. Things couldn't have got out of alignment so soon.

Any advice would be most gratefully received! At the moment, it's kind
of a problem: I'm not confident in riding at normal speed (and
especially not high speed or up a hard climb)...

Get off that bicycle immediately!
Now examine all joints and tubes minutely.
It is most likely the frame is broken,
probably a joint at the head-tube.
What is the frame material?

As for some bicycle shop checking it, they cannot be
trusted since they have not reproduced the problem you
experience.

--
Michael Press

Quoted message said:

when riding no-hands does the bike have a tendency to veer to one
side?

I wouldn't say so, no. However, it's hard to tell: the camber of the
road will make it pull to the left naturally, but I would compensate
for that by shifting my weight to the right without thinking about
it... When I'm down on my aerobars -- which, granted, is still
steerable; but close to no-hands -- there's no appreciable veering to
either side.

Quoted message said:

It is most likely the frame is broken,
probably a joint at the head-tube.
What is the frame material?

Ouch... I hope not 🙁 That sounds expensive... It's aluminium -- so I
guess that would bend, rather than shatter (a la carbon fibre).
I did have a quick look just now and everything seems fine: all the
tubes look straight (didn't note the joints). However, I'll check it
out thoroughly on Sunday, along with all other suggestions...
Thanks 🙂

If it's helpful: When it happens, it feels like (if you use your
imagination) the sidewall of the front tyre, on the right side,
suddenly collapses. Almost like going into an endo before the lurching
to the right... That's why my first investigation was the front tyre.
I'll give my innertubes a good looking at, too.

Thanks again, guys -- it's really appreciated 🙂

Michael Press said:

In article
<[email hidden]>
,
Christopher Harrison

Quoted message said:

Hi all,

Quoted message said:

Just recently my bike has suffered from a weird problem whereby it
will suddenly lurch to the right if you're leaning on that side, when
rocking to-and-fro for leverage (e.g. climbing or sprinting). It means
you have to react by quickly shifting to the left to avoid toppling
over (into the road, as we drive on the left here).

Quoted message said:

Whenever it happens, it seems to stem from the front wheel -- possibly
the tyre's sidewall. I've taken a look at both wheels and they seem to
be true (as far as I can tell) and there is no damage to either tyre
(700x23) that I can see... I've been told that it could just be that
I'm putting too much power down (i.e. the drive train is on the right
and the increased torque causes the instability). However, it
sometimes happens at low speeds (even when I'm not out of the saddle);
also, whilst it's possible that my power may have increased just
recently, I don't think it would have that significantly!
My only other line of enquiry is checking the stem and handlebars, to
make sure they're even. However, I'm pretty sure they are: I had my
bike serviced and checked-over just a few weeks ago after being hit by
a car. Things couldn't have got out of alignment so soon.

Quoted message said:

Any advice would be most gratefully received! At the moment, it's kind
of a problem: I'm not confident in riding at normal speed (and
especially not high speed or up a hard climb)...

Get off that bicycle immediately!
Now examine all joints and tubes minutely.
It is most likely the frame is broken,
probably a joint at the head-tube.
What is the frame material?

As for some bicycle shop checking it, they cannot be
trusted since they have not reproduced the problem you
experience.

--
Michael Press- Hide quoted text -

- Show quoted text -

Mike
My thought was that the damage was there when the shop examined it,
but not visible to the eye. Additional riding may well have caused it
to fail in a more noticeable way, but I agree that getting off it
immediately is great advice.
The only frame we had break was a Trek and they, through our local
shop, handled it in a very satisfactory way with an upgraded frame for
a minimal charge.
Bill C

"Christopher Harrison" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Thanks guys 🙂

When I had it serviced, after my little accident, they gave it the all-
clear and deemed it road-worthy -- and I trust them on experience...
However, I shall check these things out.

I watched a guy leaving a bike shop get hit by a car. Though the rider was
unhurt the car owner immediately had him take the bike into the shop who
declared it fine. After the driver left I looked at the bike and the seat
tube was broken at the bottom bracket.

Quoted message said:

The only frame we had break was a Trek and they, through our local
shop, handled it in a very satisfactory way with an upgraded frame for
a minimal charge.

Quoted message said:

From one Trek owner with a possible busted-up frame, that's

encouraging to hear!

Christopher Harrison said:

Quoted message said:

when riding no-hands does the bike have a tendency to veer to one
side?

I wouldn't say so, no. However, it's hard to tell: the camber of the
road will make it pull to the left naturally, but I would compensate
for that by shifting my weight to the right without thinking about
it... When I'm down on my aerobars -- which, granted, is still
steerable; but close to no-hands -- there's no appreciable veering to
either side.

Quoted message said:

It is most likely the frame is broken,
probably a joint at the head-tube.
What is the frame material?

Ouch... I hope not 🙁 That sounds expensive... It's aluminium -- so I
guess that would bend, rather than shatter (a la carbon fibre).
I did have a quick look just now and everything seems fine: all the
tubes look straight (didn't note the joints). However, I'll check it
out thoroughly on Sunday, along with all other suggestions...
Thanks 🙂

If it's helpful: When it happens, it feels like (if you use your
imagination) the sidewall of the front tyre, on the right side,
suddenly collapses. Almost like going into an endo before the lurching
to the right... That's why my first investigation was the front tyre.
I'll give my innertubes a good looking at, too.

Thanks again, guys -- it's really appreciated 🙂

I put my money on the headset. I had something very similar. The
bearings were pressed on the steering tube and would occasionally move
out of plane with the cups in the headset. If I checked the movement
of the handlebar, stop to stop, it would sometimes slightly bind, but
not always. When I rode, it would almost feel like someone was pulling
the bars from my hands and it would cause me to veer. The problem
erratic and only showed up at speed. Had to replace the fork, headset
and cups. JC

Christopher Harrison <[email hidden]> wrote:

<snip>

Quoted message said:

Any advice would be most gratefully received! At the moment, it's kind
of a problem: I'm not confident in riding at normal speed (and
especially not high speed or up a hard climb)...

Many thanks 🙂
Christopher Harrison

My money is on the rear stays or rear dropouts. Also, the rear axle
can be busted but still simi-functioning via the quick release (I've
busted three rear axles in my 40,000+ miles and each time the cycle
shop sales idiot said, "Oh that's normal flex", only to have the shop
mechanic disassemble the rear hub and have the axle come out in
pieces).

Have someone mount the bike, hold strong front wheel brake, and
repeatedly torque-untorque the rear wheel by pressing and releasing
hard on the crank (crank approx parallel to ground), first on the
right side and then on the left. While that is being done you closely
observe the rear stays and dropout area.

David

On Aug 3, 1:34 pm, holdmybeerandwatchthis <[email hidden]>

Quoted message said:

I put my money on the headset. I had something very similar. The
bearings were pressed on the steering tube and would occasionally move
out of plane with the cups in the headset. If I checked the movement
of the handlebar, stop to stop, it would sometimes slightly bind, but
not always. When I rode, it would almost feel like someone was pulling
the bars from my hands and it would cause me to veer. The problem
erratic and only showed up at speed. Had to replace the fork, headset
and cups. JC

I once had a bike start to handle badly and be
scary to impossible to ride no-hands. It turned out
that I had messed with the front fender mounting
bracket and it was rubbing (not even fully binding)
on the lower headset cup.

It's sometimes easier to detect headset problems if
you take the front wheel off and just try turning
the fork, since it has much less inertia to overcome
headset irregularities.

Ben

In article
<[email hidden]>,
Christopher Harrison

Quoted message said:

Quoted message said:

when riding no-hands does the bike have a tendency to veer to one
side?

I wouldn't say so, no. However, it's hard to tell: the camber of the
road will make it pull to the left naturally, but I would compensate
for that by shifting my weight to the right without thinking about
it... When I'm down on my aerobars -- which, granted, is still
steerable; but close to no-hands -- there's no appreciable veering to
either side.

Quoted message said:

It is most likely the frame is broken,
probably a joint at the head-tube.
What is the frame material?

Ouch... I hope not 🙁 That sounds expensive... It's aluminium -- so I
guess that would bend, rather than shatter (a la carbon fibre).
I did have a quick look just now and everything seems fine: all the
tubes look straight (didn't note the joints). However, I'll check it
out thoroughly on Sunday, along with all other suggestions...
Thanks 🙂

If it's helpful: When it happens, it feels like (if you use your
imagination) the sidewall of the front tyre, on the right side,
suddenly collapses. Almost like going into an endo before the lurching
to the right... That's why my first investigation was the front tyre.
I'll give my innertubes a good looking at, too.

Thanks again, guys -- it's really appreciated 🙂

That sounds exactly as if the down-tube/head-tube joint
is compromised. I had that once. The steering is not
crisp. The bicycle wallows with excessive over-steer.

--
Michael Press

Christopher Harrison said:

Just recently my bike has suffered from a weird problem whereby it
will suddenly lurch to the right

Perhaps its a Habanero
http://groups.google.com/group/rec.bicycles.racing/msg/1d27763212909680

in message <[email hidden]>,

Christopher Harrison (') said:

Quoted message said:

when riding no-hands does the bike have a tendency to veer to one
side?

I wouldn't say so, no. However, it's hard to tell: the camber of the
road will make it pull to the left naturally, but I would compensate
for that by shifting my weight to the right without thinking about
it... When I'm down on my aerobars -- which, granted, is still
steerable; but close to no-hands -- there's no appreciable veering to
either side.

Quoted message said:

It is most likely the frame is broken,
probably a joint at the head-tube.
What is the frame material?

Ouch... I hope not 🙁 That sounds expensive... It's aluminium -- so I
guess that would bend, rather than shatter (a la carbon fibre).
I did have a quick look just now and everything seems fine: all the
tubes look straight (didn't note the joints). However, I'll check it
out thoroughly on Sunday, along with all other suggestions...
Thanks 🙂

Aluminium cracks. Check in the weld areas, particularly. liquid ink will
flow into and along cracks, making them more visible.

Someone else's suggestion of checking you don't have a broken rear axle is
a good one, simply because it's a cheaper and simpler fix... but my money
is on a cracked or broken frame or fork. And I really, really wouldn't
ride that bike again until you've established where the problem is - a
broken frame rarely causes a bad crash, but a broken fork almost always
does.

Quoted message said:

If it's helpful: When it happens, it feels like (if you use your
imagination) the sidewall of the front tyre, on the right side,
suddenly collapses. Almost like going into an endo before the lurching
to the right.

That's why I'm worried about the fork.

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

[ This .sig subject to change without notice ]

Many thanks again, guys, for all your suggestions... I've given my
bike a good, thorough looking-over today and what I found was that all
tubes and stays are straight and uncracked, as are the forks; and no
joints are compromised. As far as I can tell, the frame is in good
condition and in proper alignment.
What I did notice, however, was that when I rotated the headset, a
"clicky" noise emanated from the head tube. It moved freely, but you
could tell that there was something amiss... So I took the headset
apart as much as I dared/could [my mechanical skills are limited!] and
cleaned-up what I could see and got some oil in there. When I put it
back together, the headset moved more freely, but the clicky noise
turned into a consistent, and rather unpleasant, grinding sound.

You may have heard about the excessive-flooding in England, just
recently, on the news. I live in the affected region and, whilst my
bike wasn't directly involved, it's taken-on a lot more water and dirt
than usual just lately -- and I haven't been able to clean it (until
today)... As such, my best guess would be that perhaps the bearings in
the headset have become compromised (that is, water-logged!).
Would anyone concur: i.e. Given that, despite my lack of experience,
the frame looks fine to me and the horrible noise coming from the head
tube, would that be enough to cause this lurching problem?

I don't have the skills to fix it, so I'll book it back into the shop
(and tell them to give it a really thorough check, in case I did miss
something). Even if it's not the headset, I know it shouldn't be
making that noise... And, yes: I'll definitely stay off it. Even when
pushing it I can feel that it's unstable!
All I can say is that at least it's clean now: So it's got some
dignity... Poor bike 🙁

Oh, sorry... I should add: both axles are fine. I forgot to check the
bottom bracket -- bugger...