Strange 'knocks' from pedals/crank area

John Latter said:

Hi,

I don't know much about cycles and if the following 'problems' indicate that only my gears need
adjusting (which I hope is the case - rather than anything more serious!) then please lemme know
'bout any online 'tutorials' that'll talk me thru it!

I have a 21-speed twist-grip all-suspension bike (Boss Reflex from Argos) and for the last few
days this has been happening:

I get a lot of 'knocks' and 'thumps' which appear to be all coming from the pedal area but they
don't happen all of the time. On occasion its as though something has given the bike a sharp rap
on the pedal shaft which I can feel thru my foot.

The diagnosis of these depends on their frequency. If you get one 'thump' per crank revolution
that's either the pedals or (more probably, because what you're describing is quite a big bump) the
bottom bracket. If once per wheel revolution, then it's a wheel bearing. If once per chain
revolution, it's a stuck link.

Quoted message said:

Sometimes it feels as though the pedal has 'jumped' forward a fraction or two.

That sounds like a loose crank. Turn the bike upside down, take one crank in each hand, and with all
your strength push down on both. Then rotate the cranks through 180 degrees and try again. If you
get a click your cranks need tightening. There are a number of different crank attachment mechanisms
but many have a simple bolt coaxial with the bottom bracket shaft which goes into the end of the
bottom bracket shaft. There may be a little cover set into the crank which covers this bolt. If you
have this sort, the bolt can simply be tightened with a socket wrench while holding the crank.

Quoted message said:

Other times (only a few though) there's a 'graunching' noise as though something's trying to mesh
(or perhaps unmesh!).

That sounded more like a bearing, which was my first guess. Turn the bike upside down, hold a crank
firmly with one hand to stop it moving, and with the other hand turn each pedal through it's full
revolution (*without* the crank moving). If you feel a click, you've found the problem. Most good
quality pedals can be stripped and serviced, but those on an Argos bike may not be worth servicing.
Remember that the left hand pedal has a left hand thread!

If you can't feel a click from either pedal, take one pedal in each hand and rotate the cranks
slowly, putting all your weight on. If you feel a click, that's a dodgy bottom bracket bearing. Most
bottom bracket bearings these days are cartridge type and cheap ones are not servicable. In any case
removing and replacing bottom bracket bearings of most types is a bit of an art, so unless you're
used to tinkering with things I'd take it to your LBS.

--
[email hidden] (Simon Brooke) jasmine.org.uk~simonOpen ↗ ,/| _.--''^``-...___.._.,; /,
\'. _-' ,--,,,--''' { \ `_-'' ' / `;;' ; ; ; ._..--'' ._,,, _..' .;.' (,_....----''' (,..--''

On Thu, 05 Feb 2004 19:35:04 GMT, Simon Brooke <[email hidden]>

Quoted message said:

John Latter said:

Hi,

I don't know much about cycles and if the following 'problems' indicate that only my gears need
adjusting (which I hope is the case - rather than anything more serious!) then please lemme know
'bout any online 'tutorials' that'll talk me thru it!

I have a 21-speed twist-grip all-suspension bike (Boss Reflex from Argos) and for the last few
days this has been happening:

I get a lot of 'knocks' and 'thumps' which appear to be all coming from the pedal area but they
don't happen all of the time. On occasion its as though something has given the bike a sharp rap
on the pedal shaft which I can feel thru my foot.

The diagnosis of these depends on their frequency. If you get one 'thump' per crank revolution
that's either the pedals or (more probably, because what you're describing is quite a big bump) the
bottom bracket. If once per wheel revolution, then it's a wheel bearing. If once per chain
revolution, it's a stuck link.

Quoted message said:

Sometimes it feels as though the pedal has 'jumped' forward a fraction or two.

That sounds like a loose crank. Turn the bike upside down, take one crank in each hand, and with
all your strength push down on both. Then rotate the cranks through 180 degrees and try again. If
you get a click your cranks need tightening. There are a number of different crank attachment
mechanisms but many have a simple bolt coaxial with the bottom bracket shaft which goes into the
end of the bottom bracket shaft. There may be a little cover set into the crank which covers this
bolt. If you have this sort, the bolt can simply be tightened with a socket wrench while holding
the crank.

Quoted message said:

Other times (only a few though) there's a 'graunching' noise as though something's trying to mesh
(or perhaps unmesh!).

That sounded more like a bearing, which was my first guess. Turn the bike upside down, hold a crank
firmly with one hand to stop it moving, and with the other hand turn each pedal through it's full
revolution (*without* the crank moving). If you feel a click, you've found the problem. Most good
quality pedals can be stripped and serviced, but those on an Argos bike may not be worth servicing.
Remember that the left hand pedal has a left hand thread!

If you can't feel a click from either pedal, take one pedal in each hand and rotate the cranks
slowly, putting all your weight on. If you feel a click, that's a dodgy bottom bracket bearing.
Most bottom bracket bearings these days are cartridge type and cheap ones are not servicable. In
any case removing and replacing bottom bracket bearings of most types is a bit of an art, so unless
you're used to tinkering with things I'd take it to your LBS.

Thanks Simon! I've had a quick read thru your advice, but as I've only got a few minutes, I'll have
to come back & digest it later - I haven't time to reply just now (nor look at my bike), but apart
from the apparently 'independent' regular noise, everything else is non-rythmmic.

Just hope there's nothing seriously wrong, that my attempts to 'fix-it' don't make things worse, and
that it doesn't cost me too much!

I appreciate your help - thankyou 🙂

--

John Latter

Model of an Internal Evolutionary Mechanism (based on an extension to homeostasis) linking Stationary-
Phase Mutations to the Baldwin Effect. members.aol.comTEM.htmlOpen ↗

'Where Darwin meets Lamarck?' Discussion Egroup groups.yahoo.comevomechOpen ↗

On Thu, 05 Feb 2004 20:43:37 +0000, John Latter <[email hidden]>

Quoted message said:

Simon Brooke said:

John Latter said:

Hi,

I don't know much about cycles and if the following 'problems' indicate that only my gears need
adjusting (which I hope is the case - rather than anything more serious!) then please lemme know
'bout any online 'tutorials' that'll talk me thru it!

I have a 21-speed twist-grip all-suspension bike (Boss Reflex from Argos) and for the last few
days this has been happening:

I get a lot of 'knocks' and 'thumps' which appear to be all coming from the pedal area but they
don't happen all of the time. On occasion its as though something has given the bike a sharp rap
on the pedal shaft which I can feel thru my foot.

The diagnosis of these depends on their frequency. If you get one 'thump' per crank revolution
that's either the pedals or (more probably, because what you're describing is quite a big bump)
the bottom bracket. If once per wheel revolution, then it's a wheel bearing. If once per chain
revolution, it's a stuck link.

Quoted message said:

Sometimes it feels as though the pedal has 'jumped' forward a fraction or two.

That sounds like a loose crank. Turn the bike upside down, take one crank in each hand, and with
all your strength push down on both. Then rotate the cranks through 180 degrees and try again. If
you get a click your cranks need tightening. There are a number of different crank attachment
mechanisms but many have a simple bolt coaxial with the bottom bracket shaft which goes into the
end of the bottom bracket shaft. There may be a little cover set into the crank which covers this
bolt. If you have this sort, the bolt can simply be tightened with a socket wrench while holding
the crank.

Quoted message said:

Other times (only a few though) there's a 'graunching' noise as though something's trying to
mesh (or perhaps unmesh!).

That sounded more like a bearing, which was my first guess. Turn the bike upside down, hold a
crank firmly with one hand to stop it moving, and with the other hand turn each pedal through it's
full revolution (*without* the crank moving). If you feel a click, you've found the problem. Most
good quality pedals can be stripped and serviced, but those on an Argos bike may not be worth
servicing. Remember that the left hand pedal has a left hand thread!

If you can't feel a click from either pedal, take one pedal in each hand and rotate the cranks
slowly, putting all your weight on. If you feel a click, that's a dodgy bottom bracket bearing.
Most bottom bracket bearings these days are cartridge type and cheap ones are not servicable. In
any case removing and replacing bottom bracket bearings of most types is a bit of an art, so
unless you're used to tinkering with things I'd take it to your LBS.

After a quick look at my bike I've found that the left-hand pedal casing is cracked - could this be
the cause of some of the problems?

I can't get the pedal off 'til I borrow some spanners off of my brother so I thought I would ask in
the meantime!

Regards,

--

John Latter

Model of an Internal Evolutionary Mechanism (based on an extension to homeostasis) linking Stationary-
Phase Mutations to the Baldwin Effect. members.aol.comTEM.htmlOpen ↗

'Where Darwin meets Lamarck?' Discussion Egroup groups.yahoo.comevomechOpen ↗

John Latter said:

John Latter said:

Simon Brooke said:

John Latter <[email hidden]> writes:

> I don't know much about cycles and if the following 'problems' indicate that only my gears
> need adjusting (which I hope is the case - rather than anything more serious!) then please
> lemme know 'bout any online 'tutorials' that'll talk me thru it!
>
> I get a lot of 'knocks' and 'thumps' which appear to be all coming from the pedal area but
> they don't happen all of the time. On occasion its as though something has given the bike a
> sharp rap on the pedal shaft which I can feel thru my foot.

The diagnosis of these depends on their frequency. If you get one 'thump' per crank revolution
that's either the pedals or (more probably, because what you're describing is quite a big bump)
the bottom bracket. If once per wheel revolution, then it's a wheel bearing. If once per chain
revolution, it's a stuck link.

After a quick look at my bike I've found that the left-hand pedal casing is cracked - could this
be the cause of some of the problems?

Depends how far the crack goes and whether the casing is integral with the race, but on a bike of
this quality it sounds probable.

Quoted message said:

I can't get the pedal off 'til I borrow some spanners off of my brother so I thought I would ask
in the meantime!

Remember that the left pedal has a left-hand thread.

--
[email hidden] (Simon Brooke) jasmine.org.uk~simonOpen ↗ ; ... of course nothing said
here will be taken notice of by ; the W3C. The official place to be ignored is on www-style or ; www-
html. -- George Lund

On Fri, 06 Feb 2004 16:35:06 GMT, Simon Brooke <[email hidden]>

Quoted message said:

John Latter said:

John Latter said:

On Thu, 05 Feb 2004 19:35:04 GMT, Simon Brooke <[email hidden]> wrote:

>John Latter <[email hidden]> writes:
>
>> I don't know much about cycles and if the following 'problems' indicate that only my gears
>> need adjusting (which I hope is the case - rather than anything more serious!) then please
>> lemme know 'bout any online 'tutorials' that'll talk me thru it!
>>
>> I get a lot of 'knocks' and 'thumps' which appear to be all coming from the pedal area but
>> they don't happen all of the time. On occasion its as though something has given the bike a
>> sharp rap on the pedal shaft which I can feel thru my foot.
>
>The diagnosis of these depends on their frequency. If you get one 'thump' per crank revolution
>that's either the pedals or (more probably, because what you're describing is quite a big bump)
>the bottom bracket. If once per wheel revolution, then it's a wheel bearing. If once per chain
>revolution, it's a stuck link.

After a quick look at my bike I've found that the left-hand pedal casing is cracked - could this
be the cause of some of the problems?

Depends how far the crack goes and whether the casing is integral with the race, but on a bike of
this quality it sounds probable.

Thanks for replying Simon, the 'stopper' that covers the nut on the pedal had disappeared & when I
tried to fit one from another bike the moulded casing of the pedal began to split in two!

I'm too much a newbie (although advanced in years!) to understand exactly "casing is integral with
the race" means but I'm gonna borrow some tools off of my brother tomorrow (the multi-purpose
spanner which came with the bike is no good), change the pedal, & see what happens - and I will (try
to) remember about the thread!

John

Quoted message said:

Quoted message said:

I can't get the pedal off 'til I borrow some spanners off of my brother so I thought I would ask
in the meantime!

Remember that the left pedal has a left-hand thread.

--

John Latter

Model of an Internal Evolutionary Mechanism (based on an extension to homeostasis) linking Stationary-
Phase Mutations to the Baldwin Effect. members.aol.comTEM.htmlOpen ↗

'Where Darwin meets Lamarck?' Discussion Egroup groups.yahoo.comevomechOpen ↗