I hate to burst your budget gravel bike bubble, but unless you’re a proficient bike mechanic, and you have access to relatively good condition used, cheap and/or free parts, or your budget is in the thousands of dollars, there’s virtually no such thing as a budget gravel bike (assuming that your definition of a “gravel bike” is that of the currently in-vogue drop bar equipped, huge tire clearing machine).
If you’re willing to expand your definition of gravel bike to say something with flat bars and a suspension fork, then you greatly increase your chances of finding a ride sufficiently capable of handling gravel roads and trails (e.g. an entry level or used hardtail mountain bike, or some variety of hybrid bike equipped with bigger tires) at a reasonable price. But for our purposes we’ll stick with the narrower, fashionable definition.
If you’re looking to buy rather than build your own, you’ll find that drop bar bikes are almost always the most expensive entry level bikes. I’m not sure exactly why this is. Maybe the integrated brake/shift levers are significantly more mechanically complex and therefore more expensive to manufacture. Maybe it’s just what the market will bear. In any case, it’s the reality of the situation. An entry level mountain bike can be had for four or five hundred bucks from your local bike shop. Ask for the entry level drop bar road bike (note: this bike will almost certainly not be capable of handling much in the way of the rough stuff) and you’ll likely be shown a bike that is nearly twice the cost or more.
Shopping used is probably much more sensible for the budget minded gravel biking enthusiast, but choose this option and you’ll be sailing on the winds of chance; there are no guarantees you’ll find what you need, and I have no concrete advice for you aside from look for something that can clear a 45mm tire at least, and good luck!
Having a mechanic put a bike together for you likely won’t be cheap either. You’ll be paying shop labor rates on assembly, maybe compatibility research, and general troubleshooting for your custom build. There goes your budget, and you haven’t even bought your bars.
If you’re trying to put a gravel bike together yourself from an old mountain bike or an old hybrid, it probably goes without saying but the more of the stock parts you keep on the bike, the cheaper your build will be. To that end, here’s a list of some parts you might consider/need to change:
- Bars: You’re a slave to fashion. They must be the DROPS!
- Brakes: Save money with cable. If the bike already has some form of cable actuated brakes, you’re in better shape. You can grab a pair of drop bar brake levers that deliver the right amount of cable pull (long or short) for the style of brake that you have for much less than you’ll find an equivalent hydraulic set up.
- Shifters: Grab a pair of bar-end shifters that are compatible with your current drivetrain. Bar-ends will be your most well integrated, cost effective option.
- Drivetrain: Leave it alone. Unless you absolutely need to change something. But remember, that change will likely have a cascading effect (as in, your money will cascade out of your wallet). Or if you want to set it up single speed, you can nix the shifters and save some dough there (and if you’re slim on mechanical savvy, this is a much simpler option to put together and maintain though it may require some extra equipment like a single speed spacer kit and chain tensioner).
- Wheels: Use what you have. Wheels are also cost prohibitive. But if you want to freshen them up on the relative cheap, slap some new rubber on ‘em.
Moral of the story: bikes are expensive and dumb. Find a better hobby. Jokes. Ride the dang bike. On the gravel.