Break the dog to the bike..in much the same manner an handler would when instructing his/her charge to heel correctly. A large empty car park (Asda job) is ideal for cementing the discipline because the handler can keep a beady eye on the dog knowing there is no obstruction to hit. A long horse training lead is helpful (over 10 ft/15ft being ideal) and a semi-choker style of collar to let the mutt know when it's got it's self offside of your allowance. Just like the walking to heel, the cycling needs to be intersperced with lots of bizarre max wall type immediate left and right turns that yank the mutt along and make it feel uncomfortable if the front wheel is not followed (identical to the left peg in the walking to heel command). Left turns should be accompanied by a shortening of the lead and practised until the mutt will simply sit down and spin around on it's rear whilst the rider 360's around it...then same to the right side. Some dogs are 'on' the discipline within minutes but it's important down Doggy land to carry the exercise through over 7 consecutive (some doggy memory bank thing) days.The aim is to allow the dog to feel happy within a certain distance of the front wheel and not when it supercedes your wants.
Nice little fell terrier suburbanreuben, grab yourself one of those flouro red collars the european hunters use for easy eyebalingl in bracken.