You can still make a claim if you are partly to blame for your accident, as long as someone else is also to blame. For example, if you are overtaking on the inside of slow moving traffic some courts may find you partly to blame, depending on the circumstances. This is called contributory negligence: under the law, whilst there are circumstances where we can claim against someone for not ensuring our safety, we must also take some responsibility for our own safety.
Contributory negligence is usually expressed in terms of a percentage - e.g. the other party is 75% to blame and you are 25% to blame.
The effect of this on your claim is that you will still have won for the purpose of being awarded compensation and for the other party having to pay your legal fees. However, your compensation will be reduced by the percentage you are found to be to blame - in other words, if you were to be awarded, for example, £2000, but were found to be 25% to blame then you would only receive £2000 less 25% = £1500.
The percentage will vary according to the circumstances of an accident. A frequent one being alleged against cyclists is failure to wear a helmet. This is a contentious issue, because helmet wear for cyclists is not compulsory in the UK, and there are arguments that helmets are not beneficial in all circumstances. If this is argued in your case, we will contest the issue strongly in your favour, but unfortunately we cannot give definitive advice at the moment, because there has been no fixed view taken by the courts as yet. Remember it will only apply in any event if you suffer a head injury, and only then to that part of your claim.