Anyone else use smaller f-sprocket?
- Thread starter borntofli
- Start date
36's and 39's are popular on freestyle BMX bikes with a 16 tooth rear sprocket for easier acceleration in confined space or with 15 tooth sprockets as a way to keep the chainwheel out of the way or to make it stronger when sideways force is applied during crankslides etc. 39's are also used on 24" wheel BMX bikes with a standard 16 tooth rear sprocket. Most 26" trials MTBs have even smaller single front chainwheels.
That is actually incorrect sir.
In BMX, the popular sizes are 28-T, and 25-T with a rear cassette of 9-T
Originally in BMX, the standard size (ratio) was 44-T/16-T. This gave the bike a rate of 55 gear inches. Most racers would bump up to a 46-T, and run at 57 gear inches.
Today, with the drive for making things more compact, smaller, and lighter...... Freewheels haven't been used since about 2003. Cassette drivers took over. When you see these little front sprockets on BMX bikes these days, the gear ratio is still 55 gear inches. This is because of the 9-T rear cassette on the back wheel. Some riders like to bump up to a 28-T, and be closer to 57 gear inches.
The same thing applies to 26" wheels.
Most cruisers come stock with a 44-T up front, and an 18-T cog in the rear.
This is a ratio of 63 gear inches. Perfect for cruising. Not putsing. It's a little higher, but it's great for maintaining a cruising speed, and commuting. Which is what they are designed for.
Unfortunately, it's a poor ratio for snap speed to pop start the China Girl.
However, getting closer to that classic BMX gear ratio is!
Take for instance my 24" mountain bike.
The sprocket looks small, and it is. It is a 23-T, but the rear is a 10-T. On a 24" wheel, that's 55 gear inches.
The same goes with my 26" mountain bike
I have a 22-T sprocket on the front, with a 10-T on the rear giving me 57 gear inches
So what I did on my motorized bicycle was gear down to a 34-t sprocket, and slapped on a 16-T cog. Now I have three pedal starts.
I hope this helps sort out any confusion. Freewheels are a thing of the past. I haven't seen one in any sort of use other than on department store bikes in over ten years.
Maybe this will help you set up a gear choice so you are not popping sweat beads off your forehead starting your engine.
Last edited:
