Greg was the seasoned cycling all-rounder. I was the mountainbiking newbie, although an experienced road cyclist. So Greg took the lead, leaving me to wipe off the spray from his bike and mine. The taste of mud taught me to shut my mouth near puddles. I took just one tumble, with little blood. I'd cautiously rolled into a Mangapurua mud-hole. It looked about 20cm deep and I expected to pedal slowly up the other side. At the bottom, however, the front wheel dug in, tipping me over the handlebars and into - you guessed it - the muddy hole.
"Are you all right?" Greg yelled back. "I should have told you to lift your front wheel over it." Which I had been doing over the smaller holes, but I should have walked through this one.
The Mangapurua Track covers 38km from the Ruatiti area - an hour's drive north of Raetihi - to a remote part of the Whanganui River at Mangapurua Landing. The track's start is well signposted on Ruatiti Rd, just short of where the shingle roadway becomes Crotons Rd.
Two-thirds of the Mangapurua is accessible to quad-bikers, although they need a permit for part of it.
We left Ohakune at 7.15am with MountainBike Station owner Darren Gamble, an accommodation provider who rents out mountainbikes and drives bikes and riders to and from tracks. The wisps of valley cloud had floated off by the time we started pedalling up the alternately clay and shingle track through farmland.
Most of the main climb of the day - 275m vertically and about 5km from the start - was over within 45 minutes and we stopped to glance back through the scrub at Mt Ruapehu, its shining, late-spring snow cover a cold contrast to our now hot, bush-clad day.
The track undulates for several kilometres, with views of Whanganui National Park's bush hills, before plunging into a fast, twisting descent to Mangapurua Stream, our occasional companion for the rest of the trip.
Soon the swingbridges start - there are 12. I walk my bike across. Greg rides some, because he can. Likewise, while traversing below several unstable bluffs I mostly walk, as requested by the Department of Conservation safety signs, and because I fear tumbling down the slopes below.
We meet pig-hunters Lindsay Graham and stepson Joe White, 11, the only people we see until the Bridge to Nowhere.
Lindsay enthuses about the cycle track, the cyclists and the birdlife. I too had noticed the constant birdsong and the flitting of tui and even bellbirds, a rarity now in most New Zealand forests.
"They ten-eightied it [poisoned the pests]," says Lindsay. "I've been coming here 25 years and it's the most amount of birds I've seen."
Greg and I stop at several of the signposted homestead sites of the families who cleared and farmed this valley until hard times and government road-funding cuts forced the last of the farms to be abandoned by 1944.
The monument to this "valley of abandoned dreams" is the Bridge to Nowhere, completed in 1936, too late to be much use to most of the settlers.
From there it is 2.7km to the Whanganui River, where Brent Firmin, of Spirit of the River Jet, whisks us and the bikes the hour downstream to Pipiriki for the drive back to Ohakune with Darren.
It's a fantastic ride, not too hard, not too much mud and a great challenge.
For our other ride, the 15km Old Coach Road track to Ohakune through Tongariro National Park, Darren drops us at the uphill end, near Horopito. Historical highlights are the old railway viaducts at Taonui and Hapuawhenua and an old railway tunnel which you can safely ride into.
The track, which is mainly through native forest, is based on the old coaching road that connected the northern and southern rail-heads a century ago when the central North Island line was nearly complete. Its surface is a mix of hard, fast-biking grit and the muddy Skyline section.
The development of the cycleways and the flowering of local business it has encouraged has helped cement the Tongariro-Whanganui area as a leading mountainbiking destination. Darren Gamble reckons the Manga-purua Track will become "the North Island's premier mountainbike ride".
* The Herald received assistance for these trips from Mountainbike Station, Spirit of the River Jet, and bike carrier rack company Freeload.
MOUNTAIN TO SEA
Four tracks, a boat ride and roads from Mt Ruapehu to the Whanganui coast through two national parks. Nearly 320km over 4 to 6 days for the full tour, but most may prefer to do a series of day rides with shuttle and jetboat transport.
Old Coach Rd: Horopito to Ohakune, 15km, 2-4 hours, easy/moderate mountainbiking.
Fishers Track: National Park to Upper Retaruke Valley, 17km, 1-2 hours, easy/moderate.
Mangapurua Track: Ruatiti area to Mangapurua Landing, Whanganui River, 38km, 3-6 hours, moderate.
Kaiwhakauka Track: Whakahoro to mid-Mangapurua Track, 16km, 3-4 hours, moderate (some upgrading yet to be done).
Amenities on offer: Mountainbike hire, track shuttle vans, jetboat pick-up, accommodation.
More information: nzcycletrail.com, nzbybike.com, visitruapehu. co.nz, nationalpark.co.nz, mountainbikestation.co.nz, spiritoftheriverjet.co.nz
ON THE TRAIL
Boxing Day: Progress report
Tuesday: Twin Coast Trail
Wednesday: Hauraki Rail Trail
Yesterday: Waikato River Trails
Today: Mangapurua and Ohakune's Old Coach Rd
TOMORROW:
Moving the roadblocks - Weekend Herald Review