Knee motion indicate setup problem?

[John Crankshaw]

I've got a pretty good setup on my bike: 30 degree leg angle at bottom of stroke and the front of
my knee is right over (or just behind) the forward pedal axle, and a nice 45-degreeish forward
body angle.

I notice sometimes on slower cadences that when my knee comes to the top of my stroke, it moves
about an inch (maybe less) in towards the top tube before plunging down.

This mean I should improve my setup? Any links to sites to help me understand if this is a problem
and how to fix?

John

 

[Qui si parla Ca]

John-<< I notice sometimes on slower cadences that when my knee comes to the top of my stroke, it
moves about an inch (maybe less) in towards the top tube before plunging down.

This mean I should improve my setup? >><BR><BR>

Discomfort? Pain?..If not I would not change anything.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"

 

[Charles Berista]

this month's Bicycling magazine has an excellent article on fit up... with pictures/angles/etc...
also on various fit programs that are available ( one maps foot/knee/etc).

charlie

 

[Werehatrack]

On Wed, 25 Feb 2004 14:30:52 GMT, "John Crankshaw"
<[email protected]> may have said:

>I've got a pretty good setup on my bike: 30 degree leg angle at bottom of stroke and the front of
>my knee is right over (or just behind) the forward pedal axle, and a nice 45-degreeish forward
>body angle.
>
>I notice sometimes on slower cadences that when my knee comes to the top of my stroke, it moves
>about an inch (maybe less) in towards the top tube before plunging down.

Normal. I believe it has to do with which muscles are used for the down stroke. If you're not having
discomfort or strain problems, ignore the motion.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

 

[Mike S.]

"John Crankshaw" <[email protected]> wrote in message
news:wk2%[email protected]...
> I've got a pretty good setup on my bike: 30 degree leg angle at bottom of stroke and the front of
> my knee is right over (or just behind) the forward pedal axle, and a nice 45-degreeish forward
> body angle.
>
> I notice sometimes on slower cadences that when my knee comes to the top
of
> my stroke, it moves about an inch (maybe less) in towards the top tube before plunging down.
>
> This mean I should improve my setup? Any links to sites to help me understand if this is a problem
> and how to fix?
>
> John
>

IME, a moving knee means that something's not quite right. Probably saddle a might low, but without
seeing you, I can't tell. I do the "old Italian with the thumb trick" with decent results: usually
~0.5cm error.

If it bothers you, I'd do something about it. If you're OK with it, you should be fine.

Mike

 

[Jp]

"John Crankshaw" <[email protected]> wrote in message news:<wk2%[email protected]>...
> I've got a pretty good setup on my bike: 30 degree leg angle at bottom of stroke and the front of
> my knee is right over (or just behind) the forward pedal axle, and a nice 45-degreeish forward
> body angle.
>
> I notice sometimes on slower cadences that when my knee comes to the top of my stroke, it moves
> about an inch (maybe less) in towards the top tube before plunging down.
>
> This mean I should improve my setup? Any links to sites to help me understand if this is a problem
> and how to fix?

This is a shot in the dark, but perhaps you're leg is flexing at the knee under the strain of
beginning the downstroke. You would expect that at a slower cadence if the slower cadence were the
result of a higher gear. If this is the case it might be something to worry about. Seems like the
answer would be strength training and/or lower gears.

JP

 

[Sheldon Brown]

John Crankshaw wrote:

> I've got a pretty good setup on my bike: 30 degree leg angle at bottom of stroke and the front of
> my knee is right over (or just behind) the forward pedal axle, and a nice 45-degreeish forward
> body angle.
>
> I notice sometimes on slower cadences that when my knee comes to the top of my stroke, it moves
> about an inch (maybe less) in towards the top tube before plunging down.
>
> This mean I should improve my setup? Any links to sites to help me understand if this is a problem
> and how to fix?

I doubt that this is a setup issue, more likely just a bad habit. I used to have a similar "hitch"
in my pedaling motion, which I noticed while riding rollers in front of a mirror.

This sort of thing can lead to knee problems (and, indeed, I used to have knee problems.)

It is also easy to correct, because the muscles involved are all under voluntary control. Just pay
attention to it, and make your knee go straight instead of sideways. If you watch this for a couple
of weeks, it will become automatic, and the problem will go away.

Sheldon "Knees Don't Hurt Anymore" Brown +----------------------------------------+
| Promote the institution of marriage: |
| Make it available to all adults! |
+----------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-
9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

[John Crankshaw]

Thanks to all who replied. Sheldon hits it pretty close, I think.

Discipline...discipline...discipline...

Sheldon Brown <[email protected]> wrote in message news:[email protected]...
> John Crankshaw wrote:
>
> > I've got a pretty good setup on my bike: 30 degree leg angle at bottom
of
> > stroke and the front of my knee is right over (or just behind) the
forward
> > pedal axle, and a nice 45-degreeish forward body angle.
> >
> > I notice sometimes on slower cadences that when my knee comes to the top
of
> > my stroke, it moves about an inch (maybe less) in towards the top tube before plunging down.
> >
> > This mean I should improve my setup? Any links to sites to help me understand if this is a
> > problem and how to fix?
>
> I doubt that this is a setup issue, more likely just a bad habit. I used to have a similar "hitch"
> in my pedaling motion, which I noticed while riding rollers in front of a mirror.
>
> This sort of thing can lead to knee problems (and, indeed, I used to have knee problems.)
>
> It is also easy to correct, because the muscles involved are all under voluntary control. Just pay
> attention to it, and make your knee go straight instead of sideways. If you watch this for a
> couple of weeks, it will become automatic, and the problem will go away.
>
> Sheldon "Knees Don't Hurt Anymore" Brown +----------------------------------------+
> | Promote the institution of marriage: |
> | Make it available to all adults! |
> +----------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-
> 9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
> http://captainbike.com http://sheldonbrown.com

 

[Hjalmar DuklæT]

"John Crankshaw" <[email protected]> wrote in message
news:wk2%[email protected]...
> I've got a pretty good setup on my bike: 30 degree leg
> angle at bottom of stroke and the front of my knee is
> right over (or just behind) the forward pedal axle, and a
> nice 45-degreeish forward body angle.
>
> I notice sometimes on slower cadences that when my knee
> comes to the top
of
> my stroke, it moves about an inch (maybe less) in towards
> the top tube before plunging down.
>
> This mean I should improve my setup? Any links to sites to
> help me understand if this is a problem and how to fix?
>
> John
>
Have a look at this site.
http://www.lemondfitness.com/products/lewedge/ Hjalmar

 

[Starskyfamily]

I am a physical therapist that has worked with a number of
cyclists with this problem, we have gotten some good results
incorporating some hip stabilizer strengthening, i.e.
kneeling on a stability ball, lunges with a focus on knee
and hip stability, etc. regards, andy

 

[Tim McNamara]

"John Crankshaw" <[email protected]> writes:

> I've got a pretty good setup on my bike: 30 degree leg
> angle at bottom of stroke and the front of my knee is
> right over (or just behind) the forward pedal axle, and a
> nice 45-degreeish forward body angle.

A "pretty good setup" means one that's comfortable for the
type of riding you do. If this is comfortable, that's good.
However, it sure sounds to me like your saddle is a bit low
if you've got a 30 degree flexion of the knee at the bottom
of the stroke.

> I notice sometimes on slower cadences that when my knee
> comes to the top of my stroke, it moves about an inch
> (maybe less) in towards the top tube before plunging down.

Lots and lots of people experience this kind of movement.
I've seen many people with this sort of thing, including
professional racers as well as tourists, recreational
riders, etc. If your knees don't hurt, it's probably not
indicative of a problem. Sometimes this sort of thing is a
benign neuromuscular issue (similar to a "golfer's hitch")
and has nothing to do with your bike fit.

> This mean I should improve my setup? Any links to sites to
> help me understand if this is a problem and how to fix?

Oh, man, there are lots and lots of Web sites with bike fit
information, and all of them will be different depending on
the target audience and the predilections of the authors.