Building A Custom Gravel Bike — What We Actually Consider That Off-The-Peg Misses

The Gravel Build Problem

Every major brand now sells a gravel bike. The specs look impressive on paper: wide tyre clearance, carbon frame, hydraulic disc brakes. But almost none of them are specced for London gravel riding — which means mixed surfaces, wet roads, mud, and the kind of conditions that expose the gaps in off-the-peg spec. When we build a custom gravel bike, here's what we actually consider that most riders don't think about until after they've bought the bike.

Tyre Clearance vs Tyre Reality

The spec sheet says up to 700x45c. That doesn't mean the frame clears a 45c tyre with mud guards. On many bikes, the actual clearance with guards fitted is 38c or smaller. That's fine for roads, but for actual gravel it might as well be a road bike. We check the actual clearance on the specific frame with the specific wheels you'll be using. Not the theoretical clearance.

Groupset For Mixed Terrain

The question we get most on gravel builds: 1x or 2x? For London gravel riding — Canal paths, Richmond Park, the South Downs — 1x with a wide range cassette (10-46 or 10-52) covers everything most riders need. The simplicity is real: no front derailleur to deal with, less to go wrong, clean chainline. 2x makes sense if you're doing mixed terrain with significant elevation change.

The Wheel Question

On a gravel build, the wheels matter more than any other component. Not the weight — the compliance and the durability. The difference between a stiff wheelset and a compliant one on mixed terrain is night and day. We spec wheels with enough compliance to absorb the rough surfaces without fatiguing you on the road sections.

The Mudguard Question

If you're commuting or riding in winter, mudguards are non-negotiable on a gravel bike in London. But most gravel frames don't have mounts for full mudguards — the rear stay clearance is the limiting factor. We check mudguard compatibility before speccing the frame. If you want full winter mudguards, we plan for it from the start.

The Tyre Pressure Question

Gravel riding lives and dies on tyre pressure. Too high: you bounce off every root and stone. Too low: you pinch flat on the first pothole. For London towpaths and chalk tracks, we typically set up for 35-40psi on 40-45mm tyres — enough grip, enough compliance, enough puncture resistance. We help you find your ideal pressure for your weight and your specific routes.

Start With The Routes

The build starts with where you actually ride. If you're mostly on the towpath and canal paths, you need compliance and mudguard clearance. If you're doing the South Downs gravel tracks, you need tyre capacity and a wider cassette range. We start with your routes, then spec the bike from there.