INTO THE RIDE #86
Alterra: a New CF Geometry
by Randy Schlitter
The Alterra pushes the CF concept as far upright as possible. It is a bold design, asking to be as much like two things possible at once. With 3 years of road testing, we now bring this bike to market with confidence that it will find ample appeal.
What the bike does is do both jobs very well with only minor trade-offs, which I will cover later. From the tech end of things what makes the Alterra a different bike from our other CF models is the subtle tweaks in frame geometry, tube sizes, and seat shaping.
With a steeper seat tube, the Alterra ends up closing the cockpit, bringing the handlebars in better reach. The trade off is a less flat-footed stance when stopped, but most who have tested the bike still comment on how easy it is to mount and the lack of tippy-toe antics at stop signs.
To the comparable Zenetik the 3/8” shorter top tube is just enough to make a difference. I prefer a forward facing curved riser. This allows plenty of room for off-seat riding, and still keeps the bar reach ergo. I also prefer the lower position for tucking under the wind.
One other nice tweak is the increase toe clearance from the front wheel; this has helped the trail riding of the MTB version and keeps the toes clear on 700c versions of that frame. The trade off is more palm pressure if you run the bars low.
With the trade-offs behind us, let’s talk about what I feel is a very magical riding bike. In testing the road verison, I have grown accustomed to attacking the hills doing very long off-the-seat climbs. Doing many seated and off-seat climbs, I concluded there is an advantage, just like a regular DF road bike, to making that grade level out. Also, off-the-seat gives you a chance to air out your bottom – things get sweaty if you stay in one place hours on end.
The bike frame is constructed of 7005 aluminum alloy, computer mitered, TIG welded, heat-treated, powder-coated, and finally assembled. The decals go under the sparkle clear coat, and are there to stay. The finish is typical amazing RANS colors, in this case what we call Rush Red. The Road is coming in at 24.15 lbs. with stock spec. It is a nice bike, with a lovely feel both in stability and handling. It is happy at any speed, from under 3 MPH to screaming above 50 MPH downhill. The ride is unlike a typical big tube aluminum DF frame, due to the longer wheel base and cantilever seat post.
I think many traditional cyclists will be surprised at what is familiar as opposed to what is not when they ride an Alterra. What they will not be accustomed to is the CF seat. When you design a bike around a seat, it eventually all comes back to that. The slanted seat tube, the longer wheelbase, and the tube sizing, all are dictated by the seat type and placement. The Alterra seat is made by removing parts of the existing CF seat. Of course a custom cushion is made to fit. The surprising outcome is how little difference in comfort there is over the other seat; however, the trimming was required due to the steeper seat tube angle.
Being a bit less in wheelbase opens up a more compact travel package. This was proven with a TR version I toted around in the back of one of my planes. I really enjoyed having a decent bike at airshows. Riding to and from the site is a great way to unwind and get in a daily work out. A steel verison of both MTB and road Alterras should happen sometime in 2010.
Mixing into our CF line-up a third geometry was a bold move, thus the 3 years of testing. At this point we plan on keeping all three geometries going. They all have their place, and work to provide various degrees of entry into the world of CF riding. The Alterra will appeal to the DF rider looking for more comfort and not willing to make that trade-off in performance.
Until next time ride safe and stay into the ride!