trek 3900 mountain bike review

In this review, we're focusing on the Trek 3900, a mountain bike that has gained popularity for its versatility and affordability. Designed for beginner and intermediate riders, the bike offers a range of features that promise a balanced cycling experience.

We'll delve into the bike's key attributes, from its quality and durability to its weight and price. Each aspect will be scrutinized to provide a well-rounded view of what this bike provides.

By the end of this review, you'll have a comprehensive understanding of the Trek 3900's strengths and weaknesses. This will equip you with the knowledge you need to decide whether this bike is the right fit for your cycling adventures.

Review of: Trek 3900

Uses: Mountain Bike

We Like

positive points  Lightweight Alpha Aluminum frame

positive points  Versatile for trails and commuting

positive points  Reliable Tektro disc brakes

positive points  Customizable with rack mounts

positive points  Budget-friendly for beginners

We Don't Like

negative points  Limited rear suspension

negative points  Suntour fork lacks durability

negative points  Stock tires wear quickly

negative points  Not suitable for rugged terrains

negative points  Basic component quality

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Trek History and Information

trek mountain bike logo

photo credit  Photo by dusa5910

Founded in 1976 by Richard Burke and Bevil Hogg, Trek Bicycle Corporation has grown from a small Wisconsin-based company into a global leader in bicycle manufacturing. Initially crafting steel touring frames in a rented barn, Trek now distributes its products in over 90 countries worldwide.

Trek has consistently led the way in cycling innovations. They debuted their first bonded aluminum frame with the Trek 2000 in 1984 and launched the industry's first carbon fiber mountain bike, the Trek 9800, in 1992.

The company continued to break new ground with the introduction of the Trek Fuel in 1999, the first full-suspension carbon fiber mountain bike, and the Trek Superfly in 2012, which was the first full-suspension 29er carbon fiber mountain bike.

Pioneering the use of computer technology in bike design and manufacturing, Trek released the first CAD-designed bicycle frame, the Trek 9900, in 1992 and the first CAM-produced frame, the Trek Y-22, in 1995.

Today, Trek's product line is extensive, featuring road bikes, mountain bikes, hybrids, electric bikes, and more. They also own several sub-brands, such as Electra Bicycle Company, Bontrager, and Diamant.

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trek 3900 mountain bike

Trek 3900 Review

  • Lightweight Alpha Aluminum frame
  • Versatile for trails and commuting
  • Reliable Tektro disc brakes
  • Customizable with rack mounts
  • Budget-friendly for beginners
  • Limited rear suspension
  • Suntour fork lacks durability
  • Stock tires wear quickly
  • Not suitable for rugged terrains
  • Basic component quality
$450 from eBay

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Entry-Level Appeal

The Trek 3900 is often described as an entry-level mountain bike, but don't let that label fool you. It's packed with features that make it a versatile choice for city commuting and trail riding. The bike's Alpha Aluminum frame offers a lightweight yet durable structure, and its SR Suntour fork provides adequate suspension for a smoother ride.

Performance and Comfort

Regarding performance, the Trek 3900 doesn't disappoint. Its Tektro hydraulic disc brakes offer reliable stopping power, a feature often praised by riders. The bike also scores high marks for its smooth shifting and rigid frame. Comfort is another strong suit, thanks to its ergonomic design and the option to upgrade to disc brakes for better control in muddy conditions.

Customization and Value

One of the standout features of the Trek 3900 is its customizability. The frame has built-in rack and fender mounts, allowing for easy additions based on your riding needs. When it comes to value, the Trek 3900 offers a lot for its price point, making it a popular choice among beginners and those looking for a reliable commuter bike.


While the Trek 3900 offers a lot of positives, it's not without its shortcomings. One of the most notable issues is the stock rear derailleur, which is described as "crappy Acera." This component tends to cause chain slapping and gear leaping when taken off-road, affecting the bike's overall performance.

Another area of concern is the front fork, particularly in the 2007 model that features a Spinner Grinder 1. This fork is criticized for being weak and prone to bottoming out on rough terrains. This limits the bike's versatility and could be a deal-breaker for those looking to tackle more challenging trails.

Lastly, the bike's V-brakes are described as "cheap," prompting some users to upgrade to disc brakes for improved stopping power. While the frame allows for such upgrades, it's an additional cost that potential buyers should consider.

In summary, while the Trek 3900 has its merits, it also has areas that could benefit from upgrades. If you're considering this bike, be prepared to invest in some component upgrades to get the most out of it.


  • Frame: Alpha Silver Aluminium
  • Front Suspension SR Suntour XCM
  • Tires: Bontrager LT3, 26x2.0"
  • Shifters: Shimano Altus
  • Front Derailleur: Shimano Altus
  • Rear Derailleur: Shimano Acera
  • Crank: Shimano M171, 42/34/24
  • Bottom Bracket 0
  • Cassette: Shimano HG31 11-32, 8 speed
  • Pedals: Wellgo nylon platform
  • Saddle: Bontrager Evoke 1
  • Seat Post Bontrager SSR
  • Handlebars: Bontrager Low Riser
  • Stem: Bontrager SSR
  • Grips: Bontrager SSR
  • Headset: 1-1/8" threadless
  • Brakeset: Tektro Novela

Pricing and Availability

The Trek 3900 mountain bike was developed and produced in the early 2010s. Since it's no longer widely produced you will unfortunately have to try and purchase one on second-hand marketplaces. I suggest looking on PinkBike or eBay.

We have found a couple of 3900's on eBay for around $500 - $600. If you look around you should find a good deal.