There are two parts to a civil claim: the first is deciding liability and the second is "How much to settle the matter?" The first may be clear, but contributory negligence can cloud the issue, and a layman is unlikely to have much clue on how to deal with this.
Then, there are differences to be drawn between personal injury and damage, especially to a pedal cycle. If a top-end Team Sky bike were to be written off, and were the rider's Rapha togs to be totally shredded, the compo would probably be less that a personal injury to a lesser mortal involving permanent disability. Damage is also relatively more easy to quantify (eg by looking a a price list) than personal injury, although lawyers do use a form of price list based on precedent.
Various things have led to personal injury claims and even personal injury lawyers being discredited such as ambulance chasers on daytime telly and people making duff claims, but if you suffer through a crash caused by somebody else you are entitled to have things put right, to the extent that £££ can make up for pain and permanent disability. A decent lawyer will sort this out for you and if your claim is too small for them to be able to represent you under the no win, no fee scheme and you have to go unrepresented to the small claims system, then they should be able to give you some pointers. Finally, if you are mistaken about the merits of your claim, a decent lawyer should also disabuse you there.