Fly’s 2021 Proton bike is a bike build to last. Best for mid-level riders who want to take it to the next level. this bike has a cassette and a freecoaster option, and each option determines how many pegs and what kind of bars you get. This bike comes in two colors and weighs only 24.9lbs.
Overview
BRAKES INCLUDED (not pictured)
The upgrades from the Neutron are a 100% CrMo frame, fork, and bars, including the new fork with an integrated cone-shaped design. Available in Cassette and Freecoaster versions like previous years, but this time, each bike has subtle details to give it a different look with the 2-piece bars on the Cassette version and the 4-piece bars on the Freecoaster version.
One new improvement that will make many people happy is the aftermarket Fuego tires and nylon hub guards that are included this year.
The Proton is our best selling model and we are stoked to make it the best Proton we’ve released yet!
The 2021 Proton is available in two colors; Savanna Dark Grey with Flat Black parts and Gloss Black with Polished parts.
RHD: Right Drive Side (Sprocket on the right side)
LHD: Left Drive Side (Sprocket on the left side)
from: fly
Other Fly Bikes
| Bike Model | Bike Price | Bike Quality |
|---|---|---|
| 2021 Fly Neo | $450 | Kids Bike |
| 2021 Fly Nova | $450 | Kids Bike |
| 2021 Fly Supernova | $540 | Mid/high level kids |
| 2021 Fly Electron | $450 | Beginner |
| 2021 Fly Neutron | $540 | Beginner |
| 2021 Fly Proton | $650 | Mid-level |
| 2021 Fly Proton FC | $650 | Mid-level |
| 2021 Fly Sion | $720 | High-level |
| 2021 Fly Orion | $690 | High-level |
| 2021 Fly Omega | $820 | High-level |
| 2021 Fly Omega FC | $820 | High-level |
Highlights
- ✅ – Full Chromoly
- ⛔️ – Under $500
- ✅ – Double Wall Rims
- ✅ – Pegs
- ✅ – Fully Sealed Bearings
- ✅ – 3 pc. Cranks
- ✅ – Freecoaster – What is a freecoaster?
- ✅ – Brakes
- ⛔️ – Gyro tabs
- ✅ – 4 pc bars – (FC option has 4pc bars)
Key Features
| Key Features |
|---|
| Freecoaster Version: Has 4pc bars, 4 pegs, and a freecoaster |
| Cassette Version: Has 2pc bars, 2 pegs, and a cassette |
| Volcano Front load stem |
| Fly Fuego 2.3″ tires |
Specs
Price: $650
Colors
Specs
| FRAME FULL 4130 CRMO / 21″ / REMOVABLE BRAKE MOUNTS |
| FORK INTEGRATED CONE SHAPE DESIGN / FULL 4130 CRMO / 1 PIECE STEER TUBE / 28MM OFFSET |
| BARS FULL 4130 CRMO / 9″ |
| GRIPS FLY DEVON / 160 MM LONG |
| STEM TREBOL TOP LOAD / FORGED / 6061-T6 ALUMINUM / 50MM |
| HEADSET INTERNAL SEALED BEARING |
| LEVER TREBOL RIGHT / FORGED / 6061 T-6 ALUMINUM |
| BRAKE TREBOL SPRINGHANGER / FORGED / 6061 T-6 ALUMINUM |
| CRANKS TREBOL 3PC / 4130 CRMO / 170 MM ARM LENGTH |
| BOTTOM BRACKET MID / SEALED BEARING |
| SPROCKET TREBOL / CNC MACHINED / 6061-T6 ALUMINUM / 25T |
| PEDALS FLY RUBEN GRAPHITE / NYLON – FIBERGLASS COMPOUND |
| CHAIN 510 TYPE / 69 LINKS |
| RIMS TREBOL / DOBLE SIDE WALLED / 6061-T6 ALUMINUM / 36H |
| FRONT HUB TREBOL FEMALE / SEALED BEARING / 3/8” FEMALE AXLE / 36H |
| REAR HUB CST OPTION TREBOL MALE CASSETTE / SEALED BEARING / 14MM MALE AXLE / 36H / 9T |
| REAR HUB FC OPTION TREBOL BUENO FC / SEALED BEARING / 14MM MALE AXLE / 36H / 9T |
| TIRES FLY FUEGO 2.30 FRONT & REAR / 60 TPI / 120 PSI |
| SEAT FLY PROTON TRIPOD / 100% SYNTHETIC LEATHER / 25 MM THICKNESS |
| POST TREBOL TRIPOD / FORGED & CNC MACHINED / 6061-T6 ALUMINUM / 135 MM |
| PEGS TREBOL HS STEEL / 2 PAIR |
| WEIGHT CST OPTION 11.2 KG / 24.6 LB |
| WEIGHT FC OPTION 11.3 KG / 24.9 LB |
Frame Geometry
A: Top Tube Length: 21″ – Learn what size is right for you here.
This is a tall toptube.
Perfect for riders that are between 5’7″ to 6’4″
Getting a top tube that is taller than suggested will make the bike feel more controlled and less responsive
Getting a top tube size that is smaller than normal will make the bike feel a lot more snappy and responsive.
B: Chain Stay Length: 13″ – Learn About Chain Stays Here
This is a medium chainstay.
A medium-chain stay balances stability and control.
A short chain stay makes the bike feel twitchy. Spins will be easy, but airing and jumping might feel hard to control.
A long chain stay will make the bike feel really controlled. Spins will feel sluggish, but manuals and air tricks will feel nice because it will be more stable and controlled.
C: Head Tube Angle: 75° – Learn About Head Tube Angles Here
Steep head tube angles make the bike “snappy” meaning more responsive to fast turns.
A less steep head tube gives you more control.
D: Seat Tube Angle: 71°
E: Bottom Bracket Height: 11.75″
F: Stand over height: 9.25″
This is a tall standover.
A tall standover gives the bike a responsive and snappy feeling. Good for barspins and controlled riding.
Bar Geometry – Learn more here
G: Rise: 9″
Riding a tall rise, will give you more leverage on the bike. Making it easier to pull back and lift the front wheel up.
H: Width: 29″
This is a medium width.
Narrow bars make barspins easier.
Wide bars give you more control and stability when steering.
I: Backsweep: 10º
What does backsweep do?
As far as I know, there is a sweet spot for backsweep. Too much will make the bike feel weird, and too little will make the bike unstable. It seems like the sweet spot is around 11º to 12º. If you need something a little more aggressive and straight feeling, go for 10º, but only do this if 11º is uncomfortable.
J: Upsweep: 2º
This is a normal upsweep!
What does upsweep do?
There is a lot of discussion about 1º upsweep vs. 4º upsweep. Some people are running experiments and testing if the greater upsweep will make drops feel better. It seems like a lot of street riders run 4º to 5º upsweep. This helps for wrist pain and lessens the impact of big drops.
Price
This is a really good mid/high-level bike that costs $650. I think this bike is a little costly. This bike has strong parts, and added quality with the pegs and the hub guards.
Quality
I love that you can choose a cassette or a freecoaster, and I also love that both are a little different. The quality of the 2021 Proton is nothing short of amazing. It has everything needed to ensure that the bike will hold up to tough riding..
Buy if you are learning:
- High airs
- transfers
- no-handers
- 360
- Grinds
- Grinds on handrails
- nose manuals
- Tire-taps
- turndowns
- Almost any trick
Don’t buy if you are learning:
- Good for all riding but best for street!
Conclusion
The Proton is such a sleek looking bike. With strong quality, and good parts. You can master the grinds because this bike comes with 2 to 4 pegs depending on the model you choose. Fly stepped it up this year by giving you hub guards with the bike.
The Proton is designed for a rider who can already do some tricks. But they need a bike to hold up for them as they progress. The added quality on this bike makes it good for mid and high-level riders. So if you are riding at a mid-level but you want a bike that will last longer… Check out the proton.
Common Questions
- Where can I buy this bike? As an affiliate for sourcebmx.com, I always recommend them. They have a warehouse in the USA so shipping is pretty fast and they do so much to support bmx. Buy it here
- Is this bike for park, dirt, or street? It is a well-rounded bike that will do good on all park, street, and dirt. However, the FC version is best for street.
- How much does it weigh? 24.9 lbs
