Gear ratios are not all as important as they are cracked up to be
- The first important question when choosing the right Gear is, what is the track like is it fast, is it downhill, has it got long straights or short straights?
- The second important question is what am I trying to achieve? That should be a simple answer to get to the first berm first so you can dictate the race from the front.
- Gear ratios differ from person to person. But once you find the right gear you should stick with it. So many times I see Kids at the track either pushing gears too hard or see the opposite and the kid is peddling his Butt off and going nowhere. So when you find the right gear stick with it.
- Gears don’t make the race it is in the mind that counts I once raced on a very tight track and everybody was dropping gears and going light cause they thought it would help along the smaller straights but my mate and I we just stuck to our normal gears only because we were to dam lazy to change them and we still came out first and second respectively, so what the moral of that little story was to show that you don’t necessarily have to change your gear all the time once you have found the sweet spot that’s the only gear you will need on any track.
- As for changing the gear in-between races it really amuses me how can you expect your child to perform better by changing one gear I don’t believe in it, but still, I see parents do it (Don’t worry parents even my father did it too me when I was a kid, I think it’s the parent’s sheer desire to win at all costs never minding what is comfortable to the child, but still I just find it hilarious)
- Gear ratios are made out to be so important in a race when they really are not it is all about going out there having the time of your life and riding as fast as you can and for those 30 to 40 seconds being free.
And remember always ride it like you stole it.
Have you ever seen a BMX gear chart and wondered what all the numbers mean? Have you wondered how to tune your gearing to make it slightly harder or easier to pedal? Well, you have come to the right place.
But first, let’s break it down to the basics.
The most common BMX gear charts are measured in gear inches. Gear Inches are used to give a numerical value to how a particular front chainring, rear cog, and tyre combination will feel.
Classic BMX gearing evolved over the years to be 44/16 on most pro-sized 20? BMX bikes, which works out to approximately 55 gear inches.
The most popular gear ratios are pretty close to a 55-inch, which just seems to feel best for most people.
The number is derived from a simple formula:
(teeth on front chainring/teeth on rear cog) X rear tire diameter in inches.
So the most common gearing in BMX for the past 10 or so years would be
(44/16) X 19.92 (Tioga Powerblock 20 x 1.75)
(2.75) X 19.92 = 54.78
Change the front chainring to a 43 and see the difference
(43/16) X 19.92 (Tioga Powerblock 20 x 1.75)
(2.6875) X 19.92 = 53.53
The tyre diameter may vary from manufacturer to manufacturer or even tire model to tire model for any standard size. For example, a common 20 x 1.75? tire is generally considered to have a tyre diameter of 19.5?. But let’s compare the Tioga Powerblock (19.92?) to a Maxxis DTH (19.48?), both are 20 x 1.75 in size but look at the difference in the measured diameter.
What this means is you can also adjust the gear inches by changing just the tyre.
(44/16) X 19.48 (Maxxis DTH 20 x 1.75)
(2.75) X 19.48 = 53.57
If you compare that to a 43/16 with a Tioga Powerblock 20 x 1.75 it’s almost the same yet all that’s changed is the tyre.
Does your gearing feel too hard to accelerate off the start hill? It could be that it’s geared too hard. Consider swapping your front sprocket to a tooth or two less and see if that helps. Alternatively, you could find a smaller rear tire. Perhaps changing from a 20 x 1.75 to 20 x 1.6 might do the trick.
If it feels too easy then yes you add a tooth or two depending on how much of a change you need or consider going to a larger tyre.
Does this calculation apply to all-wheel sizes? It sure does, but don’t worry, you aren’t expected to know all the tyre sizes, we have done all the heavy lifting for you in our gear calculator.
When changing your gearing consider the track as a whole, it may be great to get out in front of the gate, but it only matters what you finish across the finish line.
There can be quite a lot of trial and error, and changing your gearing won’t make up for poor technique. If you are not sure, be sure to ask a more experienced rider, perhaps a BMX coach can guide you in the right direction.
Check out the free bmxultra.com gear calculator to see what might work for you. It already has measurements for a lot of the most common tires in BMX racing and covers all gear combinations and tyre sizes.