Should You Build a Bike From the Frame up? Pros and Cons of Custom

Building a bike is one of the most rewarding things a cycling enthusiast can experience. Are you ready for the challenge? Here are some basic considerations and a bit of advice on how to go custom.

How to build your own bike

Written by
Bruce Lin

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Some cyclists are content to “run what they brung.” Others are addicted to the pursuit of lighter, faster, and better equipment. For those in the second category, it could be time to build your own bike component by component, from the frame up.

Maybe you have some unused spare parts. Perhaps you have a cool frame that needs some components to be ready to ride. Or, maybe you’re just curious about what it takes to build a bike, to customize every detail. This approach isn’t for everyone, but building a bike up from a bare frame can be one of the most rewarding things a gearhead can experience.

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While it’s not always as easy or affordable as buying a complete bike, building a bike piece by piece allows you to customize the spec. If you want to spend your money on a particular component and save somewhere else, you can. When you pick the parts, the cranks will be the right length, the bars will be the perfect shape, the saddle will be comfortable, and every little piece will be just how you want it to be. There’s no waste or excess. Just pure component joy. So what’s stopping you?

Build your own bike: The cost

The conventional wisdom has been that it costs less to buy a complete bike, compared to building one up from a frame. This is true for the most part. Bike manufacturers have deals with component manufacturers, and they buy in quantities that allow them to keep prices lower. For example, it costs Trek less to purchase the same crank for a complete bike than it costs you to buy it yourself.

With the growth of the used cycling marketplace, however, the frugal, patient, and tenacious buyer is often rewarded with builds that come out close to what an equivalent complete would have cost. With the deals available on lightly used frames and components, building up a frame can sometimes be the cheaper option.

You could also take quality components off your current frame and transfer them to a different frame. Switching just the frame is, in a way, the easiest way to get on a new bike without breaking the bank. I have a high-end SRAM drivetrain that’s now breathed life into four different mountain bike frames and will likely continue to do so for a couple more years.

How to build a bike: Mechanical know-how

More than anything, the technical challenge stops many cyclists from building their own bike. Buying a complete is easier. But building a bike is really not that hard! It just takes patience, perseverance, and the right tools. We live in an age of information, and there’s no reason that any buyer with just a sliver of mechanical aptitude shouldn’t be able to figure out how to put together a bike.

YouTube is now one of the best tools available to learn what goes into building a bike. There are countless Vloggers now who record and stream the complete process of assembling their own builds so you can watch along and learn. With our expert Ride Guides, it easy to figure out parts compatibility, and find the parts you’ll need to get any frame rolling.

Key steps to build your own bike:

  • Bottom bracket installation
  • Headset installation (unless it is integral with the frame)
  • Routing shifting and brake cables, if frame has internal routing
  • Mounting and adjusting drivetrain components
  • Mounting and adjusting brakes
  • Adjusting touch points: Saddle height and position; handlebar height and position
  • Wrapping handlebar tape on drop-bar bikes
  • Mounting tires
  • Taking photos for your Instagram!


Build you own bike online: Know the frame standards

There are a lot of different standards in the bike industry. If you're ordering parts online, it is key to be sure the components are compatible with your frame and each other. Here are some common bike frame standards you will have to note when preparing your own build. 

Rear dropouts 

This is where your rear wheel’s hub fits into the frame. This determines what rear wheel and hub is compatible with your frame. 

Most older frames: Quick-release dropouts; 130mm wide on road bikes and 135mm wide on mountain bikes. Vintage bikes are often 126mm and fixed-gear track frames are 120mm. 
Newer mountain bike frames: 12x148mm Boost spacing is the current standard — older models may use the 12x142mm thru-axle standard.
Super-Boost spacing: 157x12mm. This is seen on some new mountain bike models, such as Pivot. 
New road and gravel bikes: 12x142mm thru-axles (some odd models use the less common 135mm width).

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Brake mount 

This is how your rear brake mounts to the frame. 

Older mountain bike frames: Cantilever or V-brake calipers. These mount to two posts which will be on the fork legs and seat stays.  
Rim brake/older road bike frames: Rim brake calipers. These mount to a single hole located in the fork crown and a seat stay bridge.  
Modern mountain bike frames: Post-mount or I.S. mount disc brakes. I.S. mount will require the appropriate adaptor for your brake disc size. For post-mount, you might need a caliper spacer if you wish to fit a larger brake rotor.
Road, gravel, and cyclocross bikes: Older models have post mounts for disc brakes. A few years ago, flat-mount disc brake calipers became the preferred standard.

Bottom bracket 

Ooh boy, here’s where it gets complicated. There are many bottom bracket standards.

Threaded bottom brackets: These are typically English threaded, a.k.a. BSA. Bottom bracket shells are either 68mm (typically road or gravel) or 73mm wide (often MTB). Fun fact: BSA stands for Birmingham Small Arms!
Press-fit bottom brackets: There are many standards here, such as BB30, PF30, BBRight, BB386, and BB90. Generally speaking, the bearings are all pressed into the frame, not threaded. Above all, check your frame’s spec and match it to the correct bottom bracket before ordering. Some aftermarket companies also offer thread-together bottom brackets for press-fit frame shells. As the name implies, one side of the bottom bracket threads into the other, supposedly reducing the likelihood of creaking.

Front derailleur

This is nearly irrelevant on modern mountain bikes and some gravel bikes, but it’s still important for road bikes.

Braze-on front derailleur: This is a direct-mount option that doesn’t clamp the seat tube. Frames with a braze-on have a tab sticking out from the seat tube to mount the derailleur. 
Seat tube clamp front derailleur: You’ll need a derailleur clamp that matches your frame’s seat tube diameter. The dimensions can be found online but it's also very easy to measure your seat tube with calipers. Common sizes are 28.6mm, 31.8mm, and 34.9mm.   

Seatpost diameter

Make sure your post matches your frame. There are shims available to make smaller posts fit larger-diameter seat tubes, but that can make your build a little more complicated. Some road frames are sold with dedicated seatposts with aerodynamic shapes.

Road bikes: Typically use 27.2mm, but some will have larger diameter seatposts. Many Cannondales have 25.4mm seatposts. Some vintage and fixed-gear frames use 26.8mm seatposts. 
Mountain bikes: Usually use 30.9mm or 31.6mm, but there are exceptions. Some XC models use 27.2mm posts. A few bikes use oversized 34.9mm seatposts. 

Steerer tube diameter

This is how your fork fits into the frame’s head tube. Your stem and handlebars clamp to the end of the steerer tube.

Older road and mountain bikes: Straight 1 1/8” steerer tubes, or 1" for vintage models. 
Newer road and mountain bikes: Tapered steerer tubes — 1 1/2” at the bottom tapering to 1 1/8” at the top of the head tube is common for most mountain bike forks. Road, gravel, and, cross forks are usually 1 1/4" at the base and taper to 1 1/8". 
Odd sizes: Straight 1 1/4” or 1 1/2” steerer tubes seen on Giant overdrive and older Cannondale Lefty. 

Other compatibility considerations when you build a bike

Disc rotors and wheels: There are two options, Centerlock and six-bolt.
Tires and rims: If you want tubeless, make sure the rims and tires are both tubeless-ready. Note that some tubeless tires are not approved for use with hookless rims.
Cassette: Your rear wheel’s cassette driver must match your cassette. Road bikes usually employ an 11-speed freehub. On a mountain bike, you may need an XD driver for wide-range SRAM cassettes of a Microspline for 12-speed Shimano. Newer road bikes might need XDR drivers for SRAM AXS components. Campagnolo has a proprietary freehub and cassette design for both 12-speed road and 13-speed gravel groups.
Shifting components: Typically, you do not want to mix brands, and you want to always match the cog count (i.e., speeds) for cassette, rear derailleur, and shifter.
Front hub spacing and axle: Especially on mountain bikes, make sure your fork and front axle match. The modern standard is 15x110mm — also known as Boost. Some older disc brake road and cyclocross bikes have 15x100mm axles, while newer forks and wheels have 12x100mm axles.

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Embrace the challenge and build your own bike!

Plan ahead, make a list, and stay organized. But above all, approach the process of building a bike from the frame up with the right mindset. You’re likely to encounter some challenges along the way. It will be worth it when you’re done.

In the end, you’ll have a greater understanding of and appreciation for how bikes actually work. This project can deepen the connection you have with your machine. Building a bike up is an accomplishment. Every bike I’ve ever built up on my own from a bare frame has had a special place in my heart, and each has been an experience that I'll never forget.

If you're curious about building a bike up from a frame, there's no better time to start than now! Leave us a comment below with your questions or a story about a bike that you built from scratch.


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