Left sit bone slipping off saddle

[willhub]

If I have moved my cleat forward 6mm on the left side and I match the clear back to the right side, how much shim extension in mm would I need for the effective same reduction in saddle height.

Would it be 5mm of shimming be the same as 6mm of cleat stagger ?

 

[PaulSB]

If I have moved my cleat forward 6mm on the left side and I match the clear back to the right side, how much shim extension in mm would I need for the effective same reduction in saddle height.

Would it be 5mm of shimming be the same as 6mm of cleat stagger ?

I'm afraid I don't understand the question. I don't know what shimming or cleat stagger are.

My set up is to position my feet so my feet are comfortable on the pedal - this has no bearing on or relationship to saddle height. For me comfortable means no pins and needles etc.

My saddle position - forward/back is based on reach and achieving a straight line between my hip and ankle in the six o'clock position.

My saddle height is based on achieving a slight bend in the knee. Convention says this should be 15⁰ but mine is more like 10⁰

I think you need to consider balancing your leg length with a heel raiser. I asked my podiatrist friend who is also a very good cyclist about a "shim." She had never heard the term before.

 

[willhub]

So shimming is where you have the 1 to 2mm thick plastic spacers under your cleat, so simplistic, if one leg was 5mm shorter you'd have 5mm of cleat shims (the spacers)

The stagger is where my left cleat is 6mm further forward on my shoe than my right.

This has had the effect of stabilising me to some degree and allowing me to apply a more consistent power as I can apply effort with my left leg now, however it's not perfect.

What I want to do is remove the cleat stagger, so move my left cleat back so that it matches the position of the right cleat, this will then apply this instability I'm getting again.

I want to try the shims (cleat spacers).

Both of which effectively lowers the saddle in relation to the leg reaching the pedal.

I have a feeling I may get a better result with the left cleat using the shims instead, however I want to know how many millimetres of shimming will be equal to the effect of the cleat stagger (the left cleat further forward)

 

[PaulSB]

OK I understand now. My view would be you're making it very complicated by overthinking things.

Under instruction from a podiatrist who specializes in bio-mechanics I simply insert a 5mm heel raiser to correct the difference in my leg length. Doing this immediately improved my stability as it allowed me to raise my saddle. By equalising my leg length I eliminated my tendency to pull to the right - my longer leg.

In your position I would go back to basics. Ditch the shims etc. Set your cleats equally. Measure the difference in leg length simply by sitting with your feet against the skirting board. Then insert the appropriate size heel raiser. Set up your saddle accordingly.

The podiatrist who helped me with a heel raiser and shoe supports resolved all of the walking and hip issues I had. The added bonus was to improve cycling.

Don't overcomplicate things.

 

[PaulSB]

PS - for a heel raiser you need nothing more than a piece of cork.

 

[willhub]

Well the skirting board thing would show hardly any difference maybe a mm in length but it seems effectively bigger on the bike.

A heel raised wouldn't work in my shoes they'd restricted my feet unfortunately.

And 2mm of shim to reduce the amount of reach to the pedal does nothing, almost unrideable the bike is.

 

[PaulSB]

I'll leave you to it. Good luck.

 

[willhub]

I've done the skirting board and surprisingly the difference seems about 1cm, this never used to be the case.

It looks like my pelvis is not level. I am been referred by physio to someone who deals with arthritis. Also bike fit on 29th, I'd hope they can do something.

You probably think I'm ignoring your advice but I'm not, I'm simply at the end of my tether, I've been constantly tweaking my position for 12 months and had 2 bike fits, all because of this specific problem.

I gave up the other day as I've got the bike fit coming up, I've tried everything really, I haven't however tried staggering cleats or more than 3mm or so of shimming.

So after just jumping off my bike and pushing the left cleat forward I thought wow it's made me a bit stable. But it seems doing this is not recommended.

So I thought eight well I'll try the shims that are widely recommended.

The question I'm looking at is effective leg length compensation of 6mm difference between the left and right cleat, aligning cleats and using the shims how much mm of shims are needed to equate to the same equivalent change in saddle height compared to the cleat stagger.