Hi, first time post. I've had the bike for just over a year now, and the gears have just started to cause a problem. It's a Shimano 7 speed hub, the lowest 5 gears are fine, but gears 6 and 7 are lower than gear 5. It seems that there might be something inside the hub sticking - i.e.it did work very well but after we came back from France (it had been on the bike rack of the motorhome) I changed the rear sprocket to provide higher ratios. For some weeks all was fine, but then I wasn't able to get gears 6 & 7 - there are gears, but lower than gear 5. Can anyone help? I followed Flecc's advice to change the sprocket and all went fine.