Ms Perks said the cyclist was suspected to have suffered serious pelvic injuries and a broken collarbone.
The motorist, aged 21, was later arrested in Reporoa. He is scheduled to appear in the Taupo District Court tomorrow, charged with assault.
The police want to hear from anyone who saw the incident, about 12.45pm, and hope to find the driver of the car passed by the ute, a silver Toyota Hilux.
The Greenlea rescue helicopter flew the cyclist to Rotorua Hospital, where he was in a serious condition last night.
Cycle Action Auckland chairwoman Barbara Cuthbert was appalled when told of the attack, but she did not condone discourtesy by cyclists.
"You're unwise to give people the fingers. I think it's a rude behaviour. We promote courtesy on the road, from all parties. If someone has come too close to you, that's annoying, and maybe people in a fit of annoyance give the fingers; we would never recommend that.
"The fact the driver was too close is really annoying, but the unforgivable aspect was that the driver then assaulted the cyclist.
"Despite the actions of the cyclist, the bottom line is that the violence demonstrated by the ute driver is deplorable and inexcusable."
Ms Cuthbert urged cyclists to adopt the Good Bunch safe road-sharing initiative of Tamaki Drive road cyclists in Auckland. Cyclists had reported that the principle "Courtesy works - a wave and a smile" allowed riders to retain control, and promoted good behaviour by motorists.
This month, the Herald reported how Ironman entrant Glen Cornwell was hit from behind by an SUV while on a training ride in the Waitakere Ranges. He had to have surgery to stabilise a fractured vertebra.
Mr Cornwell was disgusted at being offered a partial refund, of $150, on his entry fee of more than $800 - he wanted his entry transferred to next year's race.
Last February, Jamie Curtis Pene, of Wellington, admitted punching US cyclist Russ Roca at an intersection in the city.
Safe scheme
*No more than two riders abreast, or 20 per bunch.
*200m between bunches.
*Courtesy works - give a wave and a smile.