Pulling to the right on braking

Andrew Price said:

On a new bike fitted with rim brakes front and rear, I have the
impression that the rear of the frame pulls to the right on hard
braking.

It doesn't appear to be a fork alignment problem (the bike tracks
perfectly hands-free) and when each brake is applied individually it
stops in a straight line - but when front and rear brakes are both
applied hard, it feels like the rears of the bike skids slightly to
the right.

Is that possible, or am I just imagining things?

Is it full suspension?

Andrew Price said:

On a new bike fitted with rim brakes front and rear, I have the
impression that the rear of the frame pulls to the right on hard
braking.

I assume you mean "rear wheel", the frame being laterally un-bendable.

Quoted message said:

It doesn't appear to be a fork alignment problem (the bike tracks
perfectly hands-free) and when each brake is applied individually it
stops in a straight line - but when front and rear brakes are both
applied hard, it feels like the rears of the bike skids slightly to
the right.

You use the term "skids" which in the usual sense means that the wheel
is stopped and sliding on the road. Under such conditions, the rear
wants to come to the front and even slight rider asymmetry will give a
preferred direction of rotation to the bicycle.

You didn't say what sort of bicycle this is but from your "skid"
comment I take it it is a fat tired MTB. In that case it doesn't make
much difference if it is slight enough that you aren't sure whether it
is occurring or not.

Quoted message said:

Is that possible, or am I just imagining things?

To what are you comparing the performance of this bicycle?

Jobst Brandt

In article <[email hidden]>,

Andrew Price said:

On a new bike fitted with rim brakes front and rear, I have the
impression that the rear of the frame pulls to the right on hard
braking.

It doesn't appear to be a fork alignment problem (the bike tracks
perfectly hands-free) and when each brake is applied individually it
stops in a straight line - but when front and rear brakes are both
applied hard, it feels like the rears of the bike skids slightly to
the right.

Is that possible, or am I just imagining things?

Could you be applying too much rear brake? Try this as
experiment in situations where you have plenty of room and
attention; ie not in heavy traffic.

* Approach at moderate to high speed a traffic stop.

* Well before the stop apply moderate braking with the
rear brake, say 30-50%.

* Apply the front brake lightly then progressively harder
until the rear tire starts to skid.

Does this feel the same as the symptom you experience?

--
Michael Press

Paul Cassel said:

Is it full suspension?

No, no suspension at all.

Michael Press said:

Could you be applying too much rear brake? Try this as
experiment in situations where you have plenty of room and
attention; ie not in heavy traffic.

* Approach at moderate to high speed a traffic stop.

* Well before the stop apply moderate braking with the
rear brake, say 30-50%.

* Apply the front brake lightly then progressively harder
until the rear tire starts to skid.

Does this feel the same as the symptom you experience?

Indeed it does - the problem only occurs when the rear brake is
applied hard at the same time as the front brake. Normally I use only
the front brake, but I had to use both this afternoon, when a granny
walked straight off the footpath onto the road in front of me without
even looking.

So your diagnosis is then that there is nothing wrong with the
mechanics of the bike, it's just a question of learning to "dose" the
rear brake properly?

Andrew Price said:

On a new bike fitted with rim brakes front and rear, I have the
impression that the rear of the frame pulls to the right on hard
braking.

It doesn't appear to be a fork alignment problem (the bike tracks
perfectly hands-free) and when each brake is applied individually it
stops in a straight line - but when front and rear brakes are both
applied hard, it feels like the rears of the bike skids slightly to
the right.

Is that possible, or am I just imagining things?

Are you skidding? Sometimes tire skid silently, but usually you'll
hear/feel something.

Check your rear wheel alignment. Check your bearings. Check your
swingarm/pivots if it has any. Check the crown of the road if it's
significant. Check your wheel dish. Check your head.
--
Phil

In article <[email hidden]>,

Andrew Price said:

Michael Press said:

Could you be applying too much rear brake? Try this as
experiment in situations where you have plenty of room and
attention; ie not in heavy traffic.

* Approach at moderate to high speed a traffic stop.

* Well before the stop apply moderate braking with the
rear brake, say 30-50%.

* Apply the front brake lightly then progressively harder
until the rear tire starts to skid.

Does this feel the same as the symptom you experience?

Indeed it does - the problem only occurs when the rear brake is
applied hard at the same time as the front brake. Normally I use only
the front brake, but I had to use both this afternoon, when a granny
walked straight off the footpath onto the road in front of me without
even looking.

So your diagnosis is then that there is nothing wrong with the
mechanics of the bike, it's just a question of learning to "dose" the
rear brake properly?

Yes, that is my diagnosis; nothing appears to be amiss.
When using both brakes and progressively adding more front
brake, ease off the back brake. I do this all the time,
just to know the limits.

--
Michael Press