@John Fulton I'm a bike fitter in Australia and I don't currently use saddle pressure mapping. It has it's place and I am considering the gebioMized and Velometrik systems, but it isn't essential at all. It is a useful sales tools though as it can help clients visualise the issue and appreciate benefits of the changes you suggest. The biggest benefit I see is to overcome potential communication difficulties with the client. If they are able to adequately and accurately describe what they are feeling and where they are feeling it, then my experience and their time on a few different saddles can yield a very good result. Of course if they are unable or unwilling to communicate (it happens) then using saddle pressure mapping as an external, objective tool would be useful. It can also be useful when chasing the 99th percentile of comfort and position optimisation for elite level athletes. Detecting minute movements and variations in pressure that aren't obvious to the eye or the athlete isn't conscious off. Bear in mind that the saddle pressure sensor will change the way the saddle feels so it is unfortunately introducing a variable into the process.

@Piotr Piasecki have you been using the free bike finder tools available from Velogicfit, Geometry Geeks, 99 Spokes and others. Or simple to use software like MyVelofit? Also, arm length, torso length, inseam + tibia and femur as separate measurements and foot length are all vital measurements when sizing a frame. An assessment of glute and hamstring flexibility and range of motion in your hips is also important. Especially in your situation with one body segment disproportionally longer/shorter than another. Good frame finding/sizing software will require these measurements as will any custom frame builder.

@Andy Oborne some questions that may help identify the issue that's causing your numbness: 1. do you feel even pressure under your metatarsals across your feet when you pedal or more pressure under your first metatarsal (big toe) compared to the others? 2. Do you feel like you are pushing harder with your left leg and foot than your right when you pedal? 3. Do you feel like your foot is secure inside the shoe or do you feel like your toes are clawing at the insoles as if they are subconsciously trying to 'hold on' to the shoe? 4. Does one leg track closer to the top tube than the other and is that consistent through the entire pedal stroke or does is flick or move around? 5. If you can get someone to watch you pedal ask them to crouch down behind you and look at both legs and ankles. are you pedalling straight up and down or are your legs at an angle? Does one or both ankles appear to roll inwards at any point in the pedal stroke? 6. With your shoes tightened as you'd normally have them when riding, do you feel any pressure against your big toe from the side of the shoe? 7. @Ali B suggestion to remove the insoles and stand on them to see if your feet spill over the sides is a good one. Any more than a mm or two of flesh over each side of the insole would suggest to me that the shoes aren't wide enough. I'll check back here next time I'm logged in and look at your answers. I'm a bike fitter and Lake dealer in Australia and I'm happy to help if I can.

@Josh Hall I'm a bike fitter in Australia and there is a simple test for approximating a leg length discrepancy that you can do at home with someone to observe your legs. Google "supine test for leg length discrepancy" or similar. You'll know it's the right test if it tells you to lie on your back with your knees bent at approx 90 degrees and heels level. It's indicative for physical length differences in femur and/or tibia. Whether any identified difference actually affects you on the bike is still an unknown without further assessment. With regard to cleats, are they both set to the same angle? Whether that's straight or deliberately rotated, that is one variable that you could eliminate unless you are certain that they need to be rotated differently. The advice from @Eddie Monnier about saddle height is good. If lowering the saddle feels like it engages your quads too much, try moving your saddle back by about one third of the amount by which you lowered it. Lowering your saddle will move it forward by about that one third and that may be placing your centre of mass too far forward in relation to the bottom bracket. That will make you begin to tip forward and your brain's subconscious reaction is to try to stabilise you by engaging your quads more strongly. It's worth trying. If it works then maybe a lower saddle is all you need. If it feels better on the right, but your left leg starts to feel cramped then maybe put your saddle back up and shims under the right shoe are worth trying. Consider the results of any leg length testing first. If testing suggests no difference in length then I'd be reluctant to shim as your knee tracking issue is likely to be a symptom of something else. If you are sitting skewed on the saddle then that can cause your knee to track inwards. Specifically, if the right side of your pelvis (right hip) is positioned further forward on the saddle than the left, your right knee will typically track inwards towards the top tube. It should at least be noticeably closer to the top tube than the left knee.

@Simon Hollins Most saddle manufacturers provide some instruction, either on the packaging or on their website, as to what constitutes 'level'. From there you can compare a starting position to a goal/final position for the same saddle using the angle measured across the entire length of the saddle. Some saddles lend themselves well to assessing 'level' by observing a section of the saddle and comparing that to a verified horizontal line. Some do not. What is the make/model or your saddle? You can't really compare two different models of saddle using the angle measured across the entire length of the saddle. The shape of each saddle will significantly impact the resulting angle.