Seat height, it’s easy to measure right? That's what I thought. There are many ways to measure seat height. For example, you can gauge from the bottom bracket to the top of the seat. Some people measure the total length of the seat and divide it by two to find the center. Another way is to measure the widest part of the seat. The most common way is to follow the seat tube up from the bottom bracket to the seat. The challenge is that all three methods will give you a different measurement. If you have the same seat and different frame you would follow the first two examples. What happens if you want to use a separate seat, or if you're going to try a different seat and wish to have the correct height? Keep in mind that with different seats you sit in a different position on the seat. Consequently, it can be challenging to find that location and measure it. This is how the LEOMO TYPE-S can be of use if you change your seat or you have multiple bikes with different setups.
On my race bike and training bike, I use the Selle Italia SP-01. When I ride on both bikes, my LAR is precisely the same. It is generally around 49-51 with those small deviations depending on riding scenarios. When my LAR is 49, it indicates that I am in race mode on the tip of the seat. When my LAR is 51, it suggests that I am riding more upright on the back of the seat. I feel confident using this as a guide for seat height. I can jump on a bike and by just utilizing the TYPE-S, get myself set up correctly. I can ditch the measuring tape/fit jig. I only ride with the TYPE-S for a few minutes to ensure I have different numbers than compared to my previous position. With the knowledge I've acquired by using the TYPE-S, I now know why seats don't feel the same when switched from bike to bike, even with the same measurements.
If you are following my new YouTube channel, in the session, "In-depth days training for today. 4 Sessions!!!" You will see I do some hypoxic training on the rollers with a track bike. The bike is a new bike and has a different seat tube angle. I did not have another SP-01 lying around, so I used my old Selle Italia Flight seat. I measured my seat height on my training bike, and it was 82.4mm. I set the track bike the same with the Flight seat. I measured the length of the seat and divided it by two. In doing so, I was able to find both centers to mark the point where I was going to measure it.
This is the hypoxic training I did with my track bike, on rollers. This session was straightforward with no load. Have a look at my LAR:
52.4 degrees for left leg and 57.9 degrees for the right. That is insane. I know that my FAR usually is higher on my right foot than my left. Therefore, I won't consider that when comparing the difference in LAR from left to right. The FAR (Q1) range is also very reasonable for me. Have a look at my DSS though; this is extraordinarily high for any rider.
On this day I was in a bit of a rush with my training. Also, excuse me for my break in between. I had to get a towel because sweat was getting in my eyes and on the rollers, this can be dangerous. Frequently, I would stop and lower my seat height during the ride because the TYPE-S displays these numbers in real time. I was not concerned since the focus of this session was easy tempo/hypoxic training. If I were doing strength work or some hard efforts, I would have stopped to fix the problem. I realized that with this seat I would need to lower the height to have the same position.
The next day I lowered my seat height by 5mm and completed the same session. Now take a look at the data:
Straight away my LAR decreased when seat height has been reduced. It doesn't take a rocket scientist to figure that out. Still, my LAR remained in the upper limit of what is normal for me, 51 degrees. Also, it's incredible to see how DSS plays a significant role in regards to incorrect positioning. With just a 5mm drop in seat height, I have dropped my DSS. It went from 3.5 on the left to 1 degree and my right from 32.8 to a 20.7. I just continued the session without stopping because it's just a ride of 149 watts average. Nothing that was too hard on the muscles.
So, the next hypoxic session with the track bike on the rollers. I reduced the seat height another 2mm, and this was the difference:
Let's start by looking at DSS. The left leg went lower again, from 1.0 to 0.1 degrees and the right from 20.7 down to a 6.5. This is a massive improvement. LAR is nearly spot on with my normal range (around 51 degrees) in my normal upright riding position, not in my race mode position.
You can see, that measuring seat height from the BB to a position on top of the seat varies. If I didn't have a TYPE-S, I would need to book a bike fit. You can't just trust that everything is right because the measurement from the BB to the top of the seat is the same when it is not!