Colin Dowd, one of the six commuters turned away from the train on the Friday afternoon before last, said it was the first time he had not been able to board for lack of storage space.
KiwiRail's senior communications adviser, David Miller, said when services were full people at times had to wait for another service but this was not a regular occurrence.
Ms Carter said Wairarapa was becoming a stronger region for biking and it was vital that people wishing to explore the region's trails were able to turn up at the train station and be guaranteed a place to put their bikes.
She would be bringing the issue up to discuss at the next Featherston Community Board meeting.
The Wairarapa train line is operated by KiwiRail, which operates under Greater Wellington Regional Council's bike policy.
GWRC has no immediate plans to increase capacity on the commuter train. However, they have allowed extra space for bikes on the first northbound train to Masterton this weekend for people going to the Huri Huri Wairarapa Bike Festival.
The train with extra capacity leaves Wellington station today at 9.55am.
Rick Marshall, senior communications adviser for GWRC, said there would be space for 30 extra bikes aboard the train.
It was a one-off initiative to meet the demand of the event.
He said the extended capacity on the Wellington to Wairarapa train line would not become a regular thing at this stage.
However if this weekend went "smoothly", and there was a good turnout on the train, it was possible that extra capacity would be allowed for future special events in Wairarapa, he said.
"We will be monitoring it over time because bike use is increasing and if there's a regular demand for commuter bikes then that is something we would consider in the future.
"But there's no plans at this stage to increase capacity on a permanent basis."
Mr Marshall said there had been an increase in demand on all transport services operating under the GWRC.
In 2014/15 GWRC funded 1.3 million bus, rail and ferry services, and 36.4 million passenger trips.
That equated to a 1.7 per cent increase from 2013/14.
Mr Marshall said bikes took up the same space as three passengers.
"The main thing is, especially with huge groups if they are using the line, it is best for them to speak to Tranzmetro, who can give advice on what the best service is to catch.
"There's only limited capacity, and if they know there's a huge number coming through they can plan ahead for it."