"Over the last couple of months a UCI rule has been enforced, which states that any rider who is the national champion must wear their national jersey for the race at all UCI-registered events. If you fail to comply there is a considerable fine and loss of UCI points," said Mosely.
"The space for sponsor’s logos on the national champion’s jersey is restricted, and the area available is much less than the space used by sponsors on most rider's existing jerseys. Therefore a lot of companies who pay to have a certain size logo and location on the jersey would no longer be able to have their logo visible.
"Kona has asked me to not take part in this years National Championships in case I was to win.
"Restrictions placed upon the jersey I would have to wear could effect our contract with our teams sponsors, whose financial input into the team make the team happen.
"I totally understand their decision. However, it is very disappointing for me as this is an important race for me and this year would be my only race in the UK.
"Great Britain is having an amazing year on the world cup circuit and a lot of this success is down to having a great standard of racing and riders in the UK.
"I really hope that this problem is resolved in the near future as decisions such as this put a major strain on our already fragile sport."
Russell Carty, manager of Team Kona Clarks Les Gets and president of IMTTO, a non-profit org which represents 'International Mountain bike Teams, Technical support companies and Organisers', has written to the UCI, asking for the national jersey rule to be be rescinded.
He said: "Many IMTTO members are forcing their riders not to race in national championships as they do not want their riders to be forced to wear their national jersey, the reason for this is due to the lack of branding
allowed on the jersey and also the confusion to spectators when a team has numerous national champions and they are all wearing different colour team clothing.
"Unlike road teams where there are 20-30 riders, and only 2 or 3 are in national jerseys, mountain bike teams
can be faced with all their riders not being in team colours. Teams also have the problem of selling replica team clothing, this is a source of revenue. If the riders are not wearing the team clothing it will limit the sales of the team
"Mountain biking is a sport that is losing sponsors, or having a hard time keeping them. Why is the UCI making it harder, and for what reason? The heritage of national champion is much more important on the road, why
introduce it to our discipline where there is no real interest in this?
"This is making life very difficult not only for our teams, but individual riders with no salary, who are getting fined 1,250 Swiss Francs. Why was there not more notice? We are signing contracts with sponsors in October,
ordering clothing in November, and this news came way too late for all of us.
"Please explain to us why this rule is necessary in our sport, please explain how you think it will assist the sport grow, as we can only see this as another arbitrary UCI rule, coming from road cycling."