Skip to content

Fly Bikes Proton CST 20 Inch Bike

Marsoni M251S
Sale price$343.48
Pay 4 payments of $85.87 a month.Shop Pay
Get it in 3 business days with 1 day shipping. Friday, May 29
Fly Bikes Proton CST 20 Inch BikeThis sick rig from Fly Bikes is decked with Trebol and Fly Parts to create a shredding machine! This is the Cassette (CST) version. Clickety Clack it pedals when you go back. PROTON model is the mid range BMX Bike that performs perfectly on streets but also on ramps. A resistant bike suitable for any purpose a rider could have. 100% CrMo Frame, Fork & Bars Front & rear sealed Hubs. Pegs and Hub Guards included. 3 Piece CrMo Crankset. Removable brake
Easy Shipping

Quick Dispatch:

Your Fly Bikes Proton CST 20 Inch Bike orders ship within 1-2 business days.

Delivery Options:

  • Standard: 3-7 business days
  • Fast: 2-3 business days
  • Express: 1-2 business days

Order Tracking:

You'll receive a tracking link by email once your Fly Bikes Proton CST 20 Inch Bike ships.

Need Help?
Questions about Fly Bikes Proton CST 20 Inch Bike, sizing, or delivery? We're just an email away.

Live Shipping Estimates:
Enter your location at checkout to see available shipping methods and costs for Fly Bikes Proton CST 20 Inch Bike in your area.

Get Shipping Estimates

Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
4.6 ★★★★★
Based on 2295 reviews
Sort
Highest Rating
Newest First
Oldest First
Product Reviews
N
Verified Purchase
NC Native
Louisville, US
★★★★★ 1
Poor quality, easily rips at seams.
Size: Medium, Color: Organic Cotton 5 Black Pack
Fit is great but these things do not hold up. I have some Gap hipsters that are older and they are much higher quality. These rip and tear way too easily.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on December 15, 2025
A
Verified Purchase
Alanna Humphrey
Draper, US
★★★★★ 4
Runs small. Get a size up.
Size: Large, Color: Organic Cotton 5 Pack-bwg
Runs a bit small. Kind of tight. Size up.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 26, 2026
A
Verified Purchase
Amelia Bradley
Pawtucket, US
★★★★★ 3
Elastic band is not great
Size: X-Large, Color: Organic Cotton 5 Black Pack
The cotton material is comfortable and seems like it will last some time because it isn't thin like most. However, I could really use a thicker, more durable elastic band.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on November 29, 2025
D
doctur44
Charlottesville, US
★★★★★ 5
Comfortable
Size: Large, Color: Organic Cotton 5 Black Pack
Comfortable and decent looking black underwear in a hipster, boy cut style. Material is soft and lightweight, kind of thin, but since they’re black they’re not see through at all. The elastic band at waist is also thin and not too tight so it’s very comfortable and doesn’t dig in at all. Five identical pairs in the order makes this a decent value, especially at this price and for Organic cotton material. The large size was perfect for me I sized up based on the recommendations). I’m pretty happy with this order.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on October 17, 2024
R
R. Staley
San Leandro, US
★★★★★ 5
Comfortable, great coverage, perfect fit!
Size: Medium, Color: Organic Cotton 5 Black Pack
These boy shorts are the perfect cut and extremely comfortable! They were true to size, great coverage and they fit me great. They stay in place and don't ride up in my pants so that was a huge plus too. Really glad these came in a pack of multiples cause I would definitely want more. I actually might order more anyways cause I like them so much, haha! Definitely recommend these, they are a great price for comfortable, nice quality underwear.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on October 4, 2024

recommand products