Bicycle Geometry Terms • Hacker News Board

Re: Bicycle Geometry Terms

#11

Post by danburbridge » Sat, Jun 13, 2020, 8:37 AM UTC

cranekam wrote: post #7

Great explanations! It’s really silly that seat tube length is used as the single measure of frame size. Much more important is reach and standover height, since those can’t easily be changed. A longer or shorter stem will adjust reach at the expense of changing how responsive the steering is, whereas a short seat tube can be fixed with a longer seat post. Seat tube length is also measured differently by different ma…

There is a slow movement to using stack and reach for frame sizing, which are the two most critical measurements for bike fit.

Re: Bicycle Geometry Terms

#12

Post by billsmithaustin » Sat, Jun 13, 2020, 8:42 AM UTC

seesawtron wrote: post #3

Do you think people who fix bikes or are bike enthusiasts know which of these components affect which aspect of riding? I can imagine knowing all the specific names for the parts is difficult but their affect on biking experience seems very relevant. Something that was not so obvious to me.

An example: if you want to carry saddlebags (panniers) attached to a rack over the rear wheel, it helps to have a bike with long chain stays so that your heels do not bump into your saddlebags when you pedal.

Re: Bicycle Geometry Terms

#13

Post by jsinai » Sat, Jun 13, 2020, 8:49 AM UTC

cranekam wrote: post #7

Great explanations! It’s really silly that seat tube length is used as the single measure of frame size. Much more important is reach and standover height, since those can’t easily be changed. A longer or shorter stem will adjust reach at the expense of changing how responsive the steering is, whereas a short seat tube can be fixed with a longer seat post. Seat tube length is also measured differently by different ma…

My thoughts exactly. Being on the shorter side what matters is the stand over height - too high and it greatly limits on/off/standing manoeuvrability and agility. I was surprised to learn that the smallest adult bikes tend to have a stand over height of 68-70cm. For some bikes, it’s even higher. For the lower tail of the adult height distribution, this is too tall to use comfortably.

Re: Bicycle Geometry Terms

#14

Post by orthoxerox » Sat, Jun 13, 2020, 9:02 AM UTC

What is missing is a way to convert your body's geometry to the bike's geometry.

Like, you give it your inseam length (sole to taint) and the highest pull-up bar you can grab without jumping and the site tells you what bike geometry parameters determine the correct bike size for you.

Re: Bicycle Geometry Terms

#15

Post by fit2rule » Sat, Jun 13, 2020, 9:05 AM UTC

I love this site - it is very informative.

I wonder if anyone has done something similar for music - i.e. "Musical Geometry terms" ..

Re: Bicycle Geometry Terms

#16

Post by matsemann » Sat, Jun 13, 2020, 9:11 AM UTC

orthoxerox wrote: post #14

What is missing is a way to convert your body's geometry to the bike's geometry. Like, you give it your inseam length (sole to taint) and the highest pull-up bar you can grab without jumping and the site tells you what bike geometry parameters determine the correct bike size for you.

I wrote a lengthy comment here about bike fitters. They can also help with this. It's however often more complicated than just a few measurements. They often have a special bike where literally everything can be adjusted (google retül bike), and then when the fit is done (~1h) they got lots of parameters that can be put into a DB to spit out bikeframes+gear that will work for the rider. However, my experience is that the system still needs a human expert to verify and tweak the results.

However, for a basic fit your method works. For instance when buying a Canyon they ask for your measurements for some things to recommend frame size. But this of course if very rudimentary and already assumes you want that model.

Re: Bicycle Geometry Terms

#17

Post by jibolso » Sat, Jun 13, 2020, 9:21 AM UTC

Great explanations!

Re: Bicycle Geometry Terms

#18

Post by smartbit » Sat, Jun 13, 2020, 10:12 AM UTC

audiometry wrote: post #8

If you are interested in messing around with these settings and many more, look at the great parametric bicycle cad system “Bikecad”. Brett curry maintains and updates it for eons now. And crazy licensing — one time payment gets lifetime of updates.

Nice! https://www.bikecad.ca/ Costs CAD500 is a one time fee. Runs on Linux, Mac and Windows.

A Free online version is also available. It takes >5min to load, just be patient.

Re: Bicycle Geometry Terms

#19

Post by thomasfl » Sat, Jun 13, 2020, 10:53 AM UTC

There are so many opportunities for new businesses that want to provide people with high quality well maintained bikes. In my hometown Oslo, Norway, you can see super expensive e-bikes and carbon frame roadbikes everywhere. If your bike needs repairment, you have to wait at least one month.

Re: Bicycle Geometry Terms

#20

Post by ehnto » Sat, Jun 13, 2020, 10:54 AM UTC

fit2rule wrote: post #15

I love this site - it is very informative. I wonder if anyone has done something similar for music - i.e. "Musical Geometry terms" ..

Are you able to elaborate on what you'd hope for from a "Musical Geometry" site?

I have a side project on the backburner that tries to understand the building blocks of music in order to answer questions like "What could I call this chord?" and "What notes are in the key of C?". Hence my interest!