Terpstra abandoned the Tour of Poland after crashing on a wet corner in the first stage. He suffered a deep gash to his knee and an injury to his shoulder, but x-rays proved negative.
“Niki, after his fall in Poland, was too bothered by his injury in the time trial position,” said national coach Leo van Vliet on the Dutch cycling federation's website. “Despite a customized programme, which was drawn up after his crash, he has not a good preparation for the time trial bike.
“Boom is a good substitute. Last month the two men showed similar performances in the time trials.” Boom finished second in the national championship in June, with Terpstra third.