When you build your custom bike, not only can you pick a road frameset to match your riding, but you can also hang components of your choice on it including doing crazy things like mixing Campagnolo with Shimano gear if that’s how you want to roll. Why settle for a common item, pay thousands of dollars for a road bike that will look like someone else’s clone when you can ride something unique, something you designed and built yourself?
Think about it: how else can you express your personality, your style, and your taste the same way you can when you build your own bike? And the fun of picking and choosing your own parts, packages arriving at your door day after day as if Christmas never stopped — wouldn’t you like that?
Before you start ordering stuff though, let me give you a few tips to help you avoid some common mistakes people make when they build a road bike.
Your Road Bike Frameset
Road bike frames may all look alike but there are some important variables you should know about to marry your frame with the components. Don’t make the mistake of starting your bike building project with the components first only to discover later you can’t fit them to the frame.
Another common mistake people do is they buy the frame and the fork separately. As any good frame builder will tell you, a road frameset — that is, frame and fork — is designed and built as a single unit. Both pieces integrate with each other to give you the intended handling and road feel. Unless you know what you’re doing, I suggest you buy a frameset, not a frame and then later an aftermarket fork.
Once the frameset is in your possession, or even while shopping, make sure:
- You know your frame’s inside seat tube diameter. You need to know this to pick the right size seatpost. The most common seatpost diameter size is 27.2 mm but don’t be surprised if your frame was designed for a different seatpost size.
- You know your frame’s outside seat tube diameter to match it to the front derailleur’s clamp size. Some frames are built to use braze-on derailleurs which mount directly onto the frame. If that’s the case with your frame, you won’t need the clamp. What you might need though is a seatpost clamp if you buy a frame without it, which is rare these days.
- You know your fork’s outside steerer tube diameter to match it with the stem’s inside diameter. Most modern forks today use 11/8” steerer tube. The latest trend is a tapered steerer tube with a larger diameter at the bottom of the tube (1.5”) and a smaller (11/8”) at the top. You need to know this information about your steerer not only to pick the right stem, but also the right size headset if your frameset comes without one. Good news is, most new framesets today are sold with headsets. Oh and don’t forget some spacers — these too have to match your fork steerer’s size.
- You know your frame’s bottom bracket size, and if it’s threaded, what kind of thread it is — ‘english’ or ‘italian’. You need to know your frame’s bottom bracket type and size not only to get the right bottom bracket kit, but also the right kind of crankset to match the bottom bracket. If you run into a situation where a crankset you want to use doesn’t fit the frame of your choice, you can get an adapter to solve the problem.
Road Bike Frame Geometry
Before you start shopping for a frameset, ask yourself this: What kind of a bike do I want? What its main purpose going to be?
For example, if you race criteriums on short, tight courses with a lot of corners, you’d want a sharp, “twitchy” frame that responds to the slightest change of direction you make with your hands. What you’d be looking for then is a frame with a short wheelbase and a short trail.
Look at the diagram below to see what I mean by wheelbase and trail:
Short-Trail Road Bike Frameset
The reason you’d want a short wheelbase bike for technical racing is the same one you’d want a hatchback and not a limousine when you descend on twisty roads from a mountain. That is, a bike with a long wheelbase is harder to maneuver through corners.
Trail is an attribute of frame geometry that affects its handling the most. A well designed, short-trail road frame is what makes a sharp, quick handling bike. It’s a Harley-Davidson chopper against a Japanese crotch rocket. One is designed for high-speed cruising with rock-solid stability, the other can be thrown around left and right, is touchy and goes off course at the slightest change of direction.
Three things you need to keep in mind about short-trail road frames if that’s the kind of a frameset you want:
- A short-trail frame resists angle changes when you lean into a corner. You have to push it in before the bike submits and behaves itself. In return, a short-trail frameset will do exactly what you tell it to. “It rides like it’s on rails” is how the sensation of riding fast a short-trail bike through corners is often described.
- When you exit a corner, a short-trail frame will try to climb out on its own. These two characteristics — resistance to lean into a corner and climbing out on its own out of a corner — leave little margin for error. If you make a mistake, you’ll pay for it. In skilled hands, a short-trail frame is a lethal weapon when used properly. For example, on the last corner of a race with 150 meters to go you can gap your rivals if you know how to take advantage of a short-trail frame.
- Short-trail frameset is sensitive to speed which will affect its response to rider input. At low speed, it goes straight with little input from you. Once you get to about 50 km/h (30 mp/h), the feel of the front end contact with the road almost disappears and the front wheel will want to wander around. This is why high speed descends on a short-trail frame can be scary if you’re not prepared to force it into full submission and work with it to make the bike do what you want.
I hope you can see now why short trail, short wheelbase design is used to build crit frames. These bikes are great for short, fast city racing with a lot of tight corners. In the Alps, where descends can be long and fast, a crit frame is a wrong tool for the job. This is the main difference between what I call the traditional school of frame design with its focus on the well-balanced stability of a frame built for long-distance riding, climbing and descending, and an American school with frames designed for fast, technical racing and shorter riding distances.
One more thing about short wheelbases and crit frames. A common practice to shorten a wheelbase is to build a frame with short chainstays. This brings the rear wheel closer to you. Depending on how you plan to use your bike, you may or may not like it.
To understand how short chainstays affect your ride, imagine yourself sitting at the rear end of a bus as opposed to right above its rear wheel. Above the wheel, you feel every bump and pothole on the road. If you sit at the rear end, you won’t feel as many bumps and the ride will be more comfortable. It’s the same effect on a bike — short chainstays will give you a harsher ride because the rear wheel is closer to you. This may not matter much on a short ride but the short chainstays will fatigue your body more than if you rode a bike with a longer wheelbase.
Long-Trail Road Bike Frameset
If short-trail frame characteristics don’t appeal to you, then you need to look at the other end of the spectrum: the long-trail frameset.
The effect on handling long trail has on a frame is the opposite to short trail.
Lean changes, especially at lower speeds, are light and easy. When you corner, a long-trail frame will want to take a tighter arc than you had in mind. Not a big deal when you have room to maneuver but it may catch you unaware on a wet, technical corner if you don’t pay attention to frame’s feedback.
Speed too affects long-trail frame in a different way. At low speeds maneuvers feel light and easy while high speed will give you a solid front-end feel.
This latter characteristic is great for long, fast descends but it comes with a caveat — long-trail frames are more responsive to subtle body movements and weight shifts. The faster the speed, the more sensitive it is to body movements and weight shifts which means you can mess things up on a fast descend if you don’t know how your frame behaves.
Road Bike Frameset Examples
Let’s have a look at the real-world examples of what I’m talking about here. First, a couple of short-trail frames (geometry numbers are based on what can be described as a medium size frame with a top tube between 55 and 56cm).
- Trail: 53 mm
- Chainstays: 405 mm
- Wheelbase: 990 mm
Ridley Helium is an attempt to create an F1-like handling bike based on a short 53 mm trail. With short 405 mm chainstays this frame will want to accelerate and climb like there’s no tomorrow. All you need to do is supply a pair of matching legs and a powerful engine. For its size, this Helium comes with a generous 990 mm wheelbase which will give this cannon solid stability. Two millimeters shorter and this frame will be hard to keep under control at 90 km/h (55 mp/h) on long descends with sweeping corners.
- Trail: 54 mm
- Chainstays: 410 mm
- Wheelbase: 978 mm
With short trail and wheelbase, Bianchi Specialissima is the kind of a frame you must have a full control of and know what you’re doing when speeds are high. The 410 mm chainstays are long enough for decent ride comfort.
- Trail: 56 mm
- Chainstays: 415 mm
- Wheelbase: 991 mm
Steel frames have fallen out of favor with about everybody who rides a road bike these days, and it’s too bad. But no matter how cheap and disposable carbon frames have become, steel frames refuse to go away. This Ritchey is an example of a thoughtful approach to frame building: a short 56 mm trail with 415 mm chainstays to give you a comfortable ride. And then the design is finished with a 991 mm wheelbase — long enough to give this frame a sure footing on the ground at high speeds. Combined with springy feeling of steel, this frame will be a joy to ride for long hours where hills are everywhere and you’re not on the rush to break any world records.
- Trail: 63 mm
- Chainstays: 411 mm
- Wheelbase: 999 mm
Eddy Merckx Mourenx 69 is Belgian, full stop. With 63 mm of trail and 999 mm wheelbase, it’s designed to be as stable as a brick wall. Cobbles, sure, it can handle that even though the chainstays are a little on the short side: 411 mm. Then again, you want that acceleration, don’t you? And you can handle a bit of a stiff end. Take this frame to the Alps, and you’ll feel like you own the roads you’re flying down on at 110 km/h (70mph).
- Trail: 61 mm
- Chainstays: 399 mm
- Wheelbase: 980 mm
With a long 61 mm of trail, Storck Aernario is a frame with categorical steering at high speeds if you’re confident and in full control of your every move. Aernario’s famous for its awesome stiffness and instant response to acceleration — the product of super-short 399 mm chainstays. If you build a bike with this frame, make sure your rubber is soft and at least 25 mm wide. On long rides, I would probably ride it on hand-built, high-spoke traditional wheels to add a touch of compliance to this jewel of modern frame design.
Most manufacturers don’t list trail numbers in frame geometries. If there’s no trail figure for a frame you’re interested in, you can calculate it yourself as long as you know the frame’s head tube angle and fork rake (sometimes called fork offset). Select 622 mm (700C) bead-seat diameter.
As a rough guide to trail length, anything up to 56 mm is considered short and anything above 59 mm is long. Some builders believe 57 mm is an ideal figure giving the frame enough stability without compromising too much agility. But it’s really up to you to decide what you want from your frame and this is why building your own bike is both fun and smart.