Another knee pain thread....

[TNT1]

A lay of training? Is that like sexercise?

[Morwa]

Sorry TNT...... die Brits is bietjie rof vir 'n boer... Gaan ophou oefen vir 'n rukkie....

[TNT1]

Gaan ophou oefen vir 'n rukkie....

 

Why?

 

You can have sex in lots of positions that wont aggravate your knee injury.

[Morwa]

I hear you TNT.... but all of the "kama sutra" positions start on your knees..... BEGGING to have sex!

[HandH]

You ou's have all got it wrong with your quatra patella liggamaments & stuff..

It's obvious that due to the shorter stem & lower rise of said stem by - 6 degrees

that the OP is klapping his knee against the handlebars...resulting in this pain wence by

he speaketh of....

[Mongoose!]

Anyone for knee savers?

 

PM me

Edited September 10, 2012 by Mongoose!

[Morwa]

Mongoose, I'll PM you... But thanks those adapters are going to look awesome on my XTR Race crank!

[Dogfish]

Hi Guys, instead of starting a new thread on the topic, i just want to ask some advice. I have started doing a few longer more challenging rides and find my knee's are really taking a beating. Could this be because they are not use to the distance and will take some getting used to or should be looking a bit deeper into it? i get pain toward the inside of the knee cap mainly. for days after riding its still very tender but does not hurt when walking but find it difficult to hold my weight when crouching.

[V12man]

@Morwa - One of the key factors in knee pain when changing bike to apparently similar geometries (especially 26 to 29) is the fore aft location of the seatpost top/saddle relative to the BB - and difficult to measure accurately (unless you have the right tools (plumbob and tape measure) and some good math to measure the frames setup to compare or a 3d measuring arm - small differences of a couple of cm can create pain - generally this requires some tweaking of your setup and some time to get used to it.

 

Sometimes you can see it easily visually just by lineing up the 2 bikes on the bb, and looking from the top - chances are the 29er saddle is a bit further back from the bb than the 26er.

 

I borrowed a frame geometry drawing from the momsen site to illustrate this and did a couple of edits - drop a vertical line using a plumbob (red line) from the centre of the seatpost just under the saddle. Measure the horizontal (blue line) from plumbob to centre of BB - thats the thing that changes, but I have never seen on a geometry drawing that I believe is key to this problem you have. You can calculate it using angle D and length A + seatpost height if you like - easier to measure.

 

 

Good bike fitters often use a plumbob from the knee with cranks horizontal to see this effect, and if it looks acceptable - but what it means is that a bike fitting is to some extent very specific to that bike, and does not always translate well to a new bike if you just copy it using a tape measure.

 

Assuming there is no underlying pathology or chronic overuse injury by the time you notice the pain - the rule of thumb to minimise pain is to increase cadence and move the seat up or down, forward or backward a small amount until you find the sweet spot - giventhat you have eliminated things like cleat position/new shoes etc.

 

I measured my bikes with a 3d arm earlier in the year, (engineer mate was thinking of buying one and had a demo unit) and there was 8.5cm differnces between the 2 outlying numbers - which is a lot considering I run all my saddles at 67.5cm give or take about 1 cm (so size small frames generally - all cockpit lengths (centre of seatpost just under the saddle to centre of handlebar at the stem are all within 1cm (across the 6 bikes we measured)

 

This results in the knee tracking through a slightly different internal arc for which it is not trained, and creates this minor pain - which if not resolved can lead to a major long term overuse injury.

 

This is also probably made more complex by your leg length difference - with the shorter leg having more of a kicking tipe (forward and down) action as compared to the longer leg pushing down on the pedal more vertically

 

Hope this helps you get this sorted - maybe a new visit to the bike fitter might be a good idea.