Is it the UK’s seemingly incessant rain? A poor design? Or maybe the way they are being ridden or cleaned? Why are so many owners of electric bicycles complaining that their motors need to be replaced so often? Some mountain bike owners with fourth-generation Bosch electric motors describe how they had four or five – yes five – replacement motors fitted during the two-year warranty period. Owners of other brands say theirs have only lasted 800 to 1,000 miles. The problem appears to mainly affect those riding mountain bikes in all weathers, particularly in Wales and the UK’s other wettest areas, because they are not sealed properly against water ingress. This week, one of the UK’s leading independent ebike motor specialists, the eBike Motor Centre based in Fordingbridge, Hampshire, told Guardian Money it was being sent about 250 motors a month – of all types – from owners desperate to find a cost-effective fix to problems including failed bearings, failed torque sensors and water damage to circuit boards. With manufacturers asking for up to £700 for an out-of-warranty replacement motor, it is small wonder some of those affected say they are going back to a conventional bike. Keen ebike rider Andy Fenwick, who lives in Wiltshire, contacted Guardian Money to ask whether we were aware that so many bikes had failing motors. The 71-year-old’s £5,000 Cube bike with a fourth-generation Bosch electric motor stopped working outside the warranty. Although it was resurrected by a software update and did not require a replacement, he says that after trawling the various cycling forums he was astonished by the number of motors that have had to be replaced. He says the problem is exacerbated by the fact that these units are not repairable – parts are not available from Bosch. Some owners say they’ve been told by Bosch not to ride them in wet conditions, which is clearly absurd. “Electric bikes are great for the rider and should be great for the environment, but it seems to me that many of the motors are not fit for purpose,” he says. “I have seen multiple reports of riders having between three and five replacements over two years. They appear to suffer error codes after minor shocks or being too close to a magnetic source. “Riders’ bikes have stopped working after they simply leant their bike against a lamp-post, or rode over a [magnetic] traffic light sensor grid in the road. “The big problem is water. The latest units don’t appear to be able to withstand the UK weather. Every time one fails, they have to replace the whole unit and the old one ends up in landfill. How can that be a good thing? We need better right-to-repair legislation in this area.” Fenwick has written to Bosch to ask that it improve the design and make parts available so that the motors can be repaired, but says he has received no response. Bosch says: “We place the highest value on reliability and quality, and drive units are designed for many years’ service. Nevertheless, problems can occur with any technical product. We work closely with dealers and customers to find a quick, customer-oriented solution.” He says some of the first-generation motors had experienced problems caused by water, but later models had been enhanced with improved seals and bearings. “The latest units are protected against dust and splash water, according to protection class IP54, and most error codes caused by magnetic interference disappear on restart. “In the event of a major defect, the motor will be collected for further analysis and Bosch will decide, on a case-by-case basis, whether it can be subject to a remanufacturing process. The customer gets back a drive unit in a fully functional state following an ‘end-of-line’ test,” he says. If a bike fails outside the warranty – typically two years on the motor – and the owner is denied help by the manufacturer, they will face a battle with the shop, or in chasing a cheaper repair. The Consumer Rights Act gives buyers some redress against the retailer for up to six years from purchase, although that may be difficult to obtain, given some shops will argue the owner has abused the bike. The quicker and cheaper option may be to send the motor to the eBike Motor Centre, which charges between £250 and £370 for a complete overhaul of most motors, and significantly less for smaller repairs, such as changing bearings, sensors, circuit boards and other internals which are not made available by Bosch. Customers appear delighted with the service. In the meantime, the advice to ebikers appears to be to keep your bike as dry as you can – often easier said than done – and be very careful washing it, most certainly not power washing it. And if you have the Bosch 4 motor, stay away from magnets.