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Folding bike failures and what to look out for

Small wheeled folding bikes and e-bikes, a very useful and convenient accessory but with a significant risk of folding inconveniently and potentially painfully while in use.

The problem is the usual balance of weight against durability: we’re speaking here of the frames manufactured of light alloy which is clearly desirable in terms of portability and easy stowing.

Frames have been failing without warning adjacent to the central hinge located on the main tube. There’s very little can be done to check, save an x-ray of the weld although a very close and careful inspection of the area behind the hinge plate where it is welded to the rear part of the main tube might give some warning of imminent failure if there are any almost microscopic hairline flaws in the paint.

Analysis of failed units during the course of our investigations, has identified a process called fatigue crack nucleation which is caused by poorly controlled welds. A crack may initiate adjacent to one of the beads of weld particularly if the bead is sitting on, rather than in, the parent metal. This is known as poor penetration.

In addition to the stresses concentrated at this point, the regular movement ancillary to folding and clamping will hasten the process. The crack will creep around the circumference of the tube until a critical point is reached when there’s a final catastrophic failure. Instant two-part bike and immediate dismount.

Welding a thick plate to a thin tube is a difficult process because if sufficient heat is applied to penetrate the thicker parent metal the thinner one may simply collapse. Given the excellent conductivity of aluminium the heat may be leaving as fast as it’s entering. There are many variables in the welding process, so if these are not optimized a poorly penetrating weld (which is prone to failure) may result. That’s exactly what has occurred in the examples below, belonging to a client. The parent metal can be seen to be barely touched by the beads of weld which sit on it but have barely penetrated.

Clamp plate.
Clamp plate
Clamp plate and tube.
Clamp plate and tube
The moral of the story is to consider a limited life expectancy of the machine, depending on level and type of use and the rider’s physical characteristics. Regular cleaning and inspection of the likely areas are essential. If there’s any doubt, return the bike to the dealer for a check. The rider /purchaser has redress under the Consumer Rights Act 2015 and the Consumer Protection Act 1987, the former for financial loss and injury, the latter for injury and consequences of that injury. If the worst has happened, do not part with the remains until taken informed advice. As most of these bikes are imports, the ultimate compensator will be the importer into the EU or UK. While the IBD is likely to be sympathetic he will pass the buck up the chain to wholesaler and importer rather than getting out his chequebook. The usual defences include excessive and unsuitable use, poor maintenance and lack of service from the supplying dealer, therefore it’s not a good idea to present the failed article as if its just completed a muddy cyclocross. We represent clients that have been injured as a result of many different failures and have a wealth of information available to you should you find yourself in need of a specialist solicitor. You can read more and visit our gallery of failed components here or call our 24/7 freephone helpline on 0808 100 9995 should you need our advice and assistance.

Written By:

Cycle SOS
Cycle SOS only deal with cycle accident claims. We understand cyclists, and believe that cyclists have the right to be safe on the roads. Cycle SOS The Cyclists National Helpline is made up of a highly trained team of specialist personal injury cycling lawyers that have recovered millions of pounds for people making bicycle accident claims.