Trek 3900

Is The Trek 3900 Mountain Bike A Good Bike? [Trek 3900 Review]

Trek 3900 bike is a mountain bike in the Trek 3 series. Riders keep asking how much this bike can deliver; Is Trek 3900 a good bike? Is the Trek 3900 bike of good quality?

They ask these questions because this bike is indeed a low-cost bike, which means it is affordable. At the same time, many believe that low-cost bikes are not of outstanding quality. This narrative usually affects the choice of buyers. Hence, it is essential to research a bike before you conclude that it is not a good bike.

However, this article will provide the information that you need. It will answer your questions and guide you to make the right decision.

Is The Trek 3900 Mountain Bike A Good Bike?

Yes, it is a good bike. It is beginner friendly, durable, easy to maintain, and cheap. Likewise, it possesses many other qualities that you will enjoy.

Trek 3900 Mountain Bike Specifications

The specifications of this bike are as follows

FrameAlpha Silver Aluminum w/semi – integrated head tube, bi-oval down tube w/ integrated gusset, rack, and fender mounts, disc compatible dropouts, replaceable derailleur hanger
Front SuspensionFront Suspension
HeadsetVP – A 68 –n TK, 1 1/8” semi–cartridge, sealed
StemBontrager Approved, 25 degree
SaddleBontrager SSR
Seat postSeat post
PedalsWellgo nylon platform
Rear DerailleurShimano M360
Front DerailleurShimano CO51
CrankShimano M191, 42/34/24
ShiftersShimano EF50, 8 speed
CassetteSRAM PG830 11 – 32, 8 speed
BrakesTektro V w/Shimano EF50 levers
RimsFormula Alloy FM31 hubs Bontrager 550 rims w/brushed sidewalls
TiresBontrager LT – 3 , 26 X 2.0 inches

Trek 3900 Features

This bike’s features are

Alpha Silver Aluminium Frame

The Trek brand manufacturers produce the frames of Trek bikes with Aluminum material. They use this material because it is durable, strong, and lightweight. Furthermore, they manufactured 3900 bikes with Alpha Silver Aluminum that embodies these excellent qualities.

Riders seek these outstanding qualities (durability, strength, and lightweight) because it contributes significantly to the overall performance of the bike. Durability talks about its ability to withstand pressure and the stress of rough terrains. Durability also refers to longevity. Hence you can use this bike for a long time. A strong bike frame means the frame can hold the rider’s weight. Therefore, when you sit on your bike’s saddle, its frame will hold your weight and won’t break.

Furthermore, it is lightweight for easy movement up hills and in steep areas. Its appearance is essential as well. Hence Trek manufacturers designed this bike with a semi-integrated headtube and double oval downtube.

Moreover, there are different frame sizes of Trek 3900 bikes. They are 13, 16, 18, 19.5, 21, and 22.5 inches. To know the size suitable for you, check the Trek size chart below.

Rider Height (cm)Rider Height (inches)Frame SizeValue of Frame size
148cm – 158cm4’10” – 5’2”XS13
158cm – 168cm5’2” – 5’6”XS16
168cm – 178cm5’6” – 5’10”M18
178cm – 185cm5’10” – 6’1”L19.5
185cm – 193cm6’1” – 6’4”XL21
198cm – 198cm6’4” – 6’6”XXL22.5

The 3X8 Drivetrain

The drivetrain of a bike comprises components that make the bike move. These components are pedals, cranks, chains, chainrings, cogs (cassette), and derailleur. Trek 3900 bike comes with a 3X8 drivetrain which means it has 3 chainrings connected to a cassette that contains 8 cogs. The components of a drivetrain are also referred to as gears, and they work together to ensure movement.

This drivetrain system offers you a wide range of gears to select, thus a better option than a 3X7 drivetrain. In addition, many riders applaud the Shimano Acera M360 and Shimano Altus drivetrain of Trek 3900 bikes for their durability. This bike’s drivetrain is easy to use and offers a smooth ride.

Fork And Front Suspension

Trek 3900 bike is regarded as a hardtail mountain bike which means it does not have suspension in its rear but at the front. If it were a full-suspension bike, it would have front and rear suspensions.

The fork holds the front wheel, and in it lies the front suspension. This front suspension plays the role of absorbing shocks and bumps as you ride, hence preventing you from experiencing body pains after the ride.


This bike has Tektro linear-pull brakes. However, other versions of this bike have been modified and improved with mechanical disc brakes. Linear pull brakes are simple brakes that allow you to enjoy a comfortable ride on normal flat surfaces and terrains that are less rugged. However, these brakes have a weakness of not working effectively when moving from higher to lower ground.

Nevertheless, if you want a mountain bike that will give an excellent performance in harsh and tough mountain riding, you need to change the brakes to mechanical disc brakes. Disc brakes are reliable and effective in mud and extremely rough trails.

Tires and wheels

The Bontrager LT3 tires of this bike are 26 inches in wheel diameter and 2 inches in tire width. These tires guarantee increased handling and traction on normal and rough surfaces. Nevertheless, these tires do not have good traction on rough and rugged terrains.

Similarly, these tires have poor traction in wet, woody areas. When it rains, water can come in contact with the wood in these areas, reducing friction. Friction is the force responsible for the motion of a bike’s tire on a surface. Hence, you will experience difficulty riding because the contact between your bike’s tire and the surface (friction) has reduced.

However, the good news is that you can upgrade the bike’s tires. Trek 3900 bike provides space for larger and wider tires. Thus, if you desire to ride on extremely rough trails, you can get a tire that has a tire width of 2.2 to 2.4 inches and also ensure that this tire is compatible with the bike. Wider tires provide better traction and can withstand the ruggedness of the terrain.

Rack And Fender Mounts

This bike can accommodate racks and fenders. Racks give you space to keep things as you ride. Fenders cover the wheels to prevent the throwing of mud, water, and sand into the air.

Consequently, they are of great benefit when you ride short distances. Racks help store the things you desire to carry while fenders prevent the splashing of mud and water on you and other people, hence keeping your bike parts, your clothes, and that of others clean.

So, if you want a bike that will be commuting, the Trek 3900 bike can serve that purpose. Although this bike is a mountain bike, you can mainly use this bike for short-distance rides.

Pros And Cons


It is affordable

You can purchase this bike at an affordable price. You can get one at the price of around 322 dollars. Beginners will benefit because they can start their mountain riding adventure with a bike that offers excellent qualities at an affordable price.

It Is An Excellent Bike For Beginners

Beginners can start up with this bike because they will enjoy a comfortable ride while using this bike. As beginners, they may be nervous to try challenging mountain rides. Thus this bike is a great bike that offers them that comfortable ride they desire.

It Has An Aluminum Lightweight Frame Designed In Several Sizes

Its frame is light because of Alpha silver aluminum. Therefore, you can easily ride on steep regions, which accounts for better acceleration. In addition, this bike allows you to pick the frame size that corresponds to your height for your comfort and better control.

It Has A Wide Range Of Gears

This bike has a 24-speed gear configuration. This value was derived from its 3X8 drivetrain. As a result, you can choose any gear you want using your bike shifters.

Built To Accommodate Larger And Wider Tires

This bike allows you to upgrade the tires that come with it. Hence, you can be flexible with your decisions. If you want a tire with a larger width, you can use it on this bike. However, if you do not want to involve yourself in strenuous mountain riding, stick with the tires that come with the bike.


It is not an ideal bike for strenuous mountain riding. This bike was not designed to be used for tough riding on extremely rugged terrains. Nonetheless, if you want to use this bike to suit that goal, you should upgrade the following parts.

• the linear-pull brakes to mechanical disc brakes
• the tires
• the front suspension

Comparison Between Trek 3900 And Trek 820

This comparison will give you a clearer understanding and help you appreciate their excellent qualities.
They share the following similarities

• Pull brakes
• 26 inches wheel diameter and 2 inches tire width

The table below outlines the differences between their features.

Features Trek 3900 Mountain Bike Trek 820 Mountain Bike
Frame Material Alpha Silver Aluminum Trek Custom Steel
Drivetrain 3 X 8 3 X 7
Speed Number 24 21
Weight 32 lbs ( 14.5kg) 33.68 lbs ( 15.28kg)
Front Suspension Travel SR Suntour Shock fork with 70mm travel SR Suntour Shock fork with 75mm travel

From the table, Trek 820 frame is made of steel instead of the conventional aluminum material used in other Trek bikes like the Trek 3900. Trek 3900 has more gear speed; it has a gear speed of 24 as opposed to the 21 gear speed of Trek 820. Therefore, you can select more gears on Trek 3900 using your shifters.

Trek 820 is heavier than Trek 3900 by about 2 pounds. Although Trek 820 has a higher suspension travel (75mm) in contrast with Trek 3900 (70mm), it is unsuitable for an extreme mountain ride.

Trek 820 can become a substitute for Trek 3900 if you can’t purchase Trek 3900. Yes, they are different in some features, like the 24-gear speed of Trek 3900, which is preferable. Nonetheless, Trek 820 can be an alternative because, with features like front fork suspension, Trek 820 will do a better job of absorbing shocks and bumps, hence a slightly rugged mountain bike to Trek 3900.

In addition, these bikes are in the same price range. They are both good and affordable bikes. Trek 3900 is regarded as the better bike, but this does not mean Trek 820 is a low-quality bike. Trek 820 is a good bike. Some riders may prefer this bike to Trek 3900.


Trek 3900 bike is a good bike and a good investment if you purchase one. This bike is not expensive yet offers outstanding qualities. Also, it guarantees a comfortable and smooth ride for newbies, hence a great pick for them.

This bike gives room for some of its parts to be upgraded and modified. This attribute makes this bike an asset because it can be modified to suit the rider’s desire. You can decide to use this bike for short-distance commuting while another may use it on stony surfaces and hilly areas.

It comes with different frame sizes so that riders with different heights can choose which size best fits them, makes them comfortable, and improve their handling. Moreover, among the many things that you will enjoy, this bike is durable and easy to maintain.

People Also Ask

How Much Does The Trek 3900 Mountain Bike Weigh?

Trek 3900 bike weighs 32 lbs (14.5 kg)

What Frame Sizes Are Available For The Trek 3900 Mountain Bike?

The frame sizes for this bike are 13, 16, 18, 19.5, 21, and 22.5 inches.

What Size Wheels Does the Trek 3900 Have?

The wheel size of Trek 3900 is 26 inches

What Size Trek 3900 Should I Get?

You should get the size that accommodates your height. This bike has the following sizes: extra small (XS), small (S), medium (M), Large (L), extra large (XL), and extra extra large (XXL). These sizes match the following various height ranges.

Frame Size  Rider Height
XS4’10” – 5’2”
S5’2” – 5’6”
XS5’6” – 5’10”
L5’10” –  6’1”
L6’1” – 6’4”
XXL6’4” – 6’6”

How Much Is Trek 3900?

You can purchase a Trek 3900 bike for around 322 dollars.

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