Newbie help with bike noise

[Feronni]

I've recently decided to get back into cycling and have bought a mountain
bike which I use for normal off road use (woods, canal tracks).
I've done about 70 miles in the first three weeks and can take it into the
place I boughty it from for a free check up and general tighten up.

I've noticed a certain noise when cycling which I was wondering if anyone
can advise me on its origin before I take it back for its check over.

When cycling slowly I have become aware of a knocking kind of noise that
seems to vibrate through the pedals, this seems to happen once every
revolution of the pedals.
I can still detect it at faster speeds too and it seems to happen regardless
of the gear that I am in (gears are shimano easyfire 21).

If I freewheel and turn pedals slowly whilst riding I can't detect it and
also can not detect it if I raise backwheel and crank pedals.

Its only when I'm actually cycling I hear /feel it.

Any Ideas

Thanks

[Ricardo]

Feronni wrote:

> When cycling slowly I have become aware of a knocking kind of noise that
> seems to vibrate through the pedals, this seems to happen once every
> revolution of the pedals.
> I can still detect it at faster speeds too and it seems to happen regardless
> of the gear that I am in (gears are shimano easyfire 21).
>
> If I freewheel and turn pedals slowly whilst riding I can't detect it and
> also can not detect it if I raise backwheel and crank pedals.

Is there any play in the bottom bracket axle (either axially (sorry) or
laterally?)

Alternatively, if it's a unit with ball bearings in a race (unlikely,
now everything seems to be sealed bottom brackets) it might be one or
more of the bearings has disintegrated (been there, tipped out bits of
metal when I disassembled it) - that manifested itself in a particularly
violent knocking on the crank stroke.

(Of course, if it's a sealed unit it might also be this, but you
wouldn't be able to take it apart and fix it because it's, well, sealed :-)

R.

[Feronni]

"Ricardo" > wrote in message
...

> Is there any play in the bottom bracket axle (either axially (sorry) or
> laterally?)

No, that all seems ok.

Cranking the pedals (with the back wheels raised) doesn't produce the
knocking vibration / noise (its like a clonk every revolution, you can hear
it if you listen carefully and feel the clonk vibrate through the pedals,
and it seems to be on the right pedal downstroke only) - only occurs when
cycling.

Thanks

[Simon Brooke]

in message >, Feronni
') wrote:

> I've recently decided to get back into cycling and have bought a
> mountain bike which I use for normal off road use (woods, canal
> tracks). I've done about 70 miles in the first three weeks and can
> take it into the place I boughty it from for a free check up and
> general tighten up.
>
> I've noticed a certain noise when cycling which I was wondering if
> anyone can advise me on its origin before I take it back for its check
> over.
>
> When cycling slowly I have become aware of a knocking kind of noise
> that seems to vibrate through the pedals, this seems to happen once
> every revolution of the pedals.
> I can still detect it at faster speeds too and it seems to happen
> regardless of the gear that I am in (gears are shimano easyfire 21).

This is either a pedal bearing or the bottom bracket bearing. Turn the
bike upside down and rotate the pedals with your hands, putting all
your weight on them. Do you feel the knock on one side only or on both?
If on both it's probably the bottom bracket bearing; if on one only
it's probably a pedal bearing.

These days most bottom brackets are not designed to be stripped and
serviced; many pedals still are. However, seeing this is a new bike you
shouldn't need to fix it yourself. Instead you need to point the
problem out to the shop when you take it in for its inspection, and
make sure they fix it.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; All in all you're just another hick in the mall
-- Drink C'lloid

[Andy Hewitt]

Feronni > wrote:

> "Ricardo" > wrote in message
> ...
>
> > Is there any play in the bottom bracket axle (either axially (sorry) or
> > laterally?)
>
> No, that all seems ok.
>
> Cranking the pedals (with the back wheels raised) doesn't produce the
> knocking vibration / noise (its like a clonk every revolution, you can hear
> it if you listen carefully and feel the clonk vibrate through the pedals,
> and it seems to be on the right pedal downstroke only) - only occurs when
> cycling.

Sounds like a loose crank to me. I take it this is a cotterless crank
(you'll find a pin going through it if it isn't).

--
Andy Hewitt ** FAF#1, (Ex-OSOS#5) - FJ1200 ABS
Honda Concerto 16v: Windows free zone (Mac G5 Dual Processor)
http://www.thehewitts.plus.com - now online

[Sandy Morton]

In article >, Feronni
> wrote:
> Cranking the pedals (with the back wheels raised) doesn't produce
> the knocking vibration / noise (its like a clonk every revolution,
> you can hear it if you listen carefully and feel the clonk vibrate
> through the pedals, and it seems to be on the right pedal
> downstroke only) - only occurs when cycling.

Is the left hand crank touching the frame ?

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

[Just zis Guy, you know?]

On Wed, 16 Jun 2004 21:35:02 GMT, Simon Brooke >
wrote in message >:

>This is either a pedal bearing or the bottom bracket bearing.

Or a loose / split crank. Tighten the crank bolts first!

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

[Simon Brooke]

in message >, Feronni
') wrote:

>
> "Ricardo" > wrote in message
> ...
>
>> Is there any play in the bottom bracket axle (either axially (sorry)
>> or laterally?)
>
> No, that all seems ok.
>
> Cranking the pedals (with the back wheels raised) doesn't produce the
> knocking vibration / noise (its like a clonk every revolution, you can
> hear it if you listen carefully and feel the clonk vibrate through the
> pedals, and it seems to be on the right pedal downstroke only) - only
> occurs when cycling.

Probably the right pedal bearing, then. Which is good since it's a lot
easier to replace the pedals than the bottom bracket (and it's often
possible to service pedals anyway).

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/
.::;===r==\
/ /___||___\____
//==\- ||- | /__\( MS Windows IS an operating environment.
//____\__||___|_// \|: C++ IS an object oriented programming language.
\__/ ~~~~~~~~~ \__/ Citroen 2cv6 IS a four door family saloon.

[Doug Steel]

"Just zis Guy, you know?" > wrote in message >...
> On Wed, 16 Jun 2004 21:35:02 GMT, Simon Brooke >
> wrote in message >:
>
> >This is either a pedal bearing or the bottom bracket bearing.
>
> Or a loose / split crank. Tighten the crank bolts first!

I've also had similar symptoms at points on my :
hybrid - it was a pedal bearing
road bike - it was a loose pedal
mtb - it was a loose crank bolt

Make sure the pedals and crank bolts are tight then see if the problem persists.

Doug

[Feronni]

"Ricardo" > wrote in message
...
> Alternatively, if it's a unit with ball bearings in a race (unlikely,
> now everything seems to be sealed bottom brackets) it might be one or
> more of the bearings has disintegrated (been there, tipped out bits of
> metal when I disassembled it) - that manifested itself in a particularly
> violent knocking on the crank stroke.
>
> (Of course, if it's a sealed unit it might also be this, but you
> wouldn't be able to take it apart and fix it because it's, well, sealed
:-)
>
> R.

Thanks for all your help and comments.

Took it back to the shop and they reckon its a bottom bracket that has gone.
They've had 3 bikes (same models) with similar problems that have gone the
same way, so they reckon on it being a batch of faulty shimano sealed units
they have, so they are going to replace it for me.

Thanks