Things have changed a bit around here

If you’ve been here before, you’ll notice things look a little different on the site. I’ve been working on a major update and today, it has finally gone live.

Here are a few things to keep an eye out for:

Calculator Updates

The two primary bike geometry calculators have been merged into one new one. The new calculator includes all the functions of the previous Bike Geometry Calculator and adds a couple additional parameters to change: change to rear center length (adjustable chainstays) and a reach adjust headset. The Multiple Bike Geometry Comparison Tool has been added to this calculator so you can now compare your original bike against your modified bike against up to 2 more, or you can compare 3 bikes, with no considerations of modifying the geometry.

A few new measurements have been added to the calculator, nothing earth-shattering, but people have asked for some more info, so the calculators continue to get longer!

Fields are now color-coded to better track multiple bikes with the bike display.

Bike Display Graphics

The graphical display of the bikes has been improved in the new bike geometry calculator. The actual seat angle is now shown in the display, with a kink in the seat tube, so if you know the actual seat angle (either from the geo chart, measuring your seat post angle with your phone or a protractor, or eyeballing it in Microsoft Paint or whatever you do) you can really dial in the appearance of the display of the bike along with improving the accuracy of the measurements. Just have a look at the new plotting style and you’ll see what I mean. The effective seat angle is still there, it’s now shown as a dotted line. I’ve also added crank length as an input (and saddle to pedal distance as an output) and show the corresponding pedal position. Standover height is also now included and used to locate the top tube and seat tube junction.

You can now toggle the display of each bike on and off and overlay bikes based on the wheels sitting on the ground, the rear axles aligning, and the bottom brackets aligning. 

New Tire Diameter Estimator Calculator

I’ve put together a simple tire diameter estimator to help populate the tire diameter fields in the calculator. The math is basic (rim bid seat diameter + two times the tire diameter) so it obviously isn’t perfect, but it will help get you in the ballpark. It’s linked in the description section of the bike geometry calculator and also in the calculators section of the menu.


I wrestled with this one…and I’ve decided to put a PayPal donation page together. I have always intended and will continue to keep the site free to use. I don’t expect anything of anyone, but if you would like to help support paying the hosting bills, I would certainly appreciate it.

I welcome feedback on anything. I don’t have a background in programming or web design and I’m learning as I go, so I can’t work all the miracles that people have asked for, but I’m always keen to hear from you and give it a go.

If you notice anything on the new site layout looking wonky or any links directing to the wrong thing or just dead links, please email me through the contact page. I’ve tested the new calculator myself but it hasn’t been tested by anyone else. If you find a glitch, let me know!