Saddle Height confusion

CyclingBantam

Following reading the article on Bikeradar about saddle height and the 109% method I am quite confused. It states you measure your inseam length (84cm) then adjust your saddle to 109% of that (91.5cm) measuring from the top of the saddle to the pedal axcel?

When I have done this my saddle has to be raised by about 10cm which is clearly wrong, my leg would not straighten? Am I missing something or measuring rom the wrong place? (I'm measuring from the pedal axcel (Bottom Bracket) to the middle of the saddle.

Very confused?

shockedsoshocked

Isn't it from the saddle to the actual pedal, not the bottom bracket?

softlad

I just tried the 109% method and got almost exactly the same result - a saddle height approximately 10cm higher than my current setting.

With that height, I would not even be able to reach the pedal at full extension.. :shock:

CyclingBantam

Yes it is. I will now leave and we will never mention this again! :oops:

djb1971

The quickest way to get a starting point for your saddle height is to stand on a hard floor with bare feet. Put your back against the wall and with a thick book ( 1" ) pull it under your crotch square with the wall as far as it will go until it goes no further, mark the wall where the top of the book is. This is your inseam.

You can the take 10 cm from this measurement and this gives you the distance from the centre of the bottom bracket (where the crank arms join to the frame ) to the top of the saddle. You can then adjust this measurement a couple of mm either way to suit your riding style.

neeb

I'm suspicious of all of these methods for calculating saddle height based on measuring lengths of various bits of your anatomy while off the bike. If I use the method above, I get a value /at least/ 6cm greater than what I know is my ideal saddle height (from a bike fit and a lot of hassle in the past with problems due to wrong saddle height). Also, it's impossible to get a consistent value with this sort of measurement. If you repeat it 4 or 5 times you will get values that differ by 2 or 3 centimeters, because human beings just aren't that rigid - a slight muscle movement or difference in pressure when pressing the book into your crotch will make a big difference to the result. So the idea that you can adjust it by 2mm either way to suit riding style just becomes meaningless (just my opinion, no offence meant!). Unfortunately however, a difference in saddle height of a centimeter does make a big difference, so it's actually really difficult to get it right. I think the best methods are the ones that rely on measuring the angle of the knee joint while on the bike with the cranks at a particular position. By far the biggest advantage I got from having a bike fit was to get my saddle height and forward/back position properly sorted. Prior to that I'd fiddled around a lot and was always way out, and I'm pretty pedantic and obsessive when it comes to that sort of thing.

djb1971

You pull the book or whatever you use to your pubic bone, I get within 2-3mm every time.

I didn't say adjust it once 2mm to get your riding height. You need to adjust every week 2-3mm to get to your ideal height. Using my measurement above on Bens inseam , the saddle height is 74 cm to the bb and using 172.5 crank arms is 91.4 cm to the pedal axle. So it's not too far out. If most people do that and drop 6cm off the height they wouldn't be getting 20 deg. of bend. I've also used a goniometer an the above guide puts me in 26deg knee bend which falls nicely between the recommended 25-30 deg.

At the end of the day we are all made differently with different length bones etc so it's best to experiment with varying heights over time. It's right when your knees don't hurt .

Steve Kish

The 109% method is inner leg x 1.09 should be the distance between saddle top and centre of the pedal with the crank at the lowest point and in exact line with the seat pillar.

I use another method. In just socks, I sit on the saddle with my heel on the pedal. According to guidelines, you should j-u-s-t about be able to turn both pedals backwards without rocking sideways on the saddle.

Kneesaway

If you are good with Maths have a look at BikeDynamics.co.uk. They use knee angles to set saddle height and have a formula based on measurements between various bony bits. They recommend 150 degrees max.

DuncSF

You could study and take some useful information from www.competitivecyclist.com.
The sizing section is quite a useful way to compare your set up - I'm not suggesting its a substitiute for getting a professional fitting but it does give some exact measurements and different riding styles, which I've found useful.
I've used it to confirm my studies and tweaks for my bike fitting and it can be quite close. If you search on the web there is also a site giving the pro riders bike specificatons including their measurements, such as bottob bracket to saddle height, reach and saddle nose to handlebar measurement - interesting reading.
One key factor none of these 'templates' cover is the flexibility of each rider and differences in things like femur length and arm and torso length.