Discovering a crack in your bike frame in the middle of a tour is cause to worry. What can you do, to stop the crack widening? And will you have to abandon your trip?

Framebuilder Marten Gerritsen of M-gineering dishes out some advice for this worst-case scenario.

Marten distributes bike parts and builds touring and randonneur frames in fillet brazed steel. Marten also gives courses in bike maintenance for touring cyclists, or takes a break as mechanic for road racing teams.

The Question: “I’ve never had a frame break on tour but I have had a crack appear in my frame. Thankfully, I was able to get to a decent welder who could fix it, but that’s not always possible. What is the best way to deal with a cracked frame, when you are a few days from the next repair shop? Is there a way to protect or at least reinforce the damaged area?”

The Answer: “First of all if your steel frame breaks on the road, try to find a bodyshop. Cars are fixed everywhere, made of thin metal like a bicycle and both welding or brazing are common. Shaping a reinforcement patch will be second nature. Blacksmiths are used to things you can pound on with hammers.

Aluminium and Titanium welding is highly specialized. It is unlikely you will find somebody with the skills on the road, and aluminium would be very weak after welding without a heat treatment.

With DIY repairs you try to do two things: take the strain from the crack to stop it from growing, and provide a secondary loadpath should the frame fail. Try to bridge the crack with splints and hoseclamps or multiple windings of steel wire. Join the broken pieces with a stick cut to size and wrap it with rope.

In boat building country you could also try to find glass cloth (or hemp) and epoxy resin and wrap a bandage over the break (clean and sand the frame first to ensure bonding) This will be a messy job for the unexperienced, but whole bicycles can be built this way.

And do clean your bike some times. It might well enable you to spot a growing crack before it becomes disastrous” -Marten of M-gineering

Thanks to Marten of M-gineering for answering the question. Get in touch to submit a question of your own to Ask A Mechanic.