Friday, August 21, 2015

29+ and full suspension - BRAAP

Yes, correct saddle height. I'm a freak.

A few days ago I posted a quick picture of the bike I'm calling "BRAAP". I'll let you decide if that's an acronym, and if so, what it stands for (Big Rowdy Alces Alces Proletarian?) But I can say that taken as a whole, it stands for super, super fun. And yes, full custom full suspension frames are now officially available (priced the same as the Ventana/WW configuration for now at $2500 w/shock), drop me a line for details.

First, the basics. Here's the bike:


The executive summary here: modern XC geometry, 100mm travel, lots of standover, pretty darn short stays, pretty darn low BB. Designed to just *barely* allow the use of a Thomson dropper post with the saddle clamped at full ~28 degree downward tilt.

I wanted a long-day go-anywhere bike that would be fun for exploring rough/undeveloped trails, as well as snappy and responsive enough to be fun on a lunch ride. It's built super beefy (all Supertherm all the time!) because 1) I wanted to be able to loan it out to buddies/customers without worrying about how big they were, and 2) I crash. Sometimes hard. There's also the fact that honestly, being a weight weenie about a 3" tire bike when you're approaching 40 and have 2 small kids is ridiculous. If I wanted to be faster I'd drink less beer and ride more. The complete bike weighs about 28 pounds with fairly nice but not crazy parts.

And, I'll be blunt: I got what I was going for. And then some (with some inevitable tradeoffs, of course). This is my favorite full suspension bike ever, and I must have owned 30 or so by now.

Loads of Chupacabra clearance
I'll do another post next week for those folks who are interested about the nitty-gritty of the swingarm and seatstays. Suffice to say for now that they're a mixture of straight-gauge 4130 and 304 stainless (for bearing fittings) along with a LOT of probably unnecessary work to attach everything to the dropouts (I'll use rockers next time and for customer bikes - much simpler/lighter/cleaner).

So, how does it ride?

In a word, it's like having a short-travel DH bike on the downhill, and a really capable (albeit not all that light) XC bike on the climbs. It has insane gobs of traction in even the worst off camber gravel type situations. It wheelies and manuals and pops around really nicely (though not as nicely as Stupidmobile, since that bike has a wheelbase that's almost 3" shorter!) It's extremely capable on steep terrain going up or down - no wander on slow techy climbs, tons of confidence on steep roll-ins and rough fast descents.

There are tradeoffs, of course:
-3" tires are pretty slow going uphill unless the terrain is really rough. You won't be getting any Strava PRs on your local dirt road climb on this bike.
-I wanted a very low bb, because I love how low bb bikes ride. In technical stuff when pedaling, pedal strikes can be pretty frequent (and potentially dangerous if you're going fast!)
-They are intact so far, but the bike demands to be ridden really fast on rough gnar, and I'm guessing I'll eventually shred my probably too-light Chupacabra tires.
-Chupacabras (and 100mm travel) aren't great for going off big drops or hitting big jumps at the bike park. To be fair, though, this bike was never intended to be a full-on DH sled and doesn't have the travel or geometry to be ridden that way.

Curved bridge next time!
Some people will also find the combination of larger tires and suspension to be just too much damping out of trail feedback - the ride can feel "numb" on smoother sections of trail and while you might be going really fast - in some cases it actually doesn't feel very fun because the bike is doing so much of the work. That's a line that everyone has to find for themselves, though, and on the trails I tend to like best (rough XC) this bike is perfect.

I'm pretty excited about this bike, not just because it's a blast to ride, but also because I can now do really fun and weird stuff with full suspension bikes (FS fatbike? FS 29er with 400mm chainstays? Super low/high/long/short/fat/whatever? All doable) and let the geek flag fly. Not everyone is going to prefer 29+ (or even fit on it) but that's the nice thing here - I can do 27.5+, 26+, 24" fatbike, 20", mixed wheel sizes... anything.

I'm not about to stop riding Stupidmobile (currently set up as a rigid singlespeed with, natch, a Chupacabra on the front) since Park City has a metric ton of trails that are way too smooth for any form of suspension at all. But when I wander into the shop, this is the bike I usually grab.


Anonymous said...

That is pretty cool, Walt! Looking forward to seeing the write up on the suspension pieces.

Andy D. said...

I love the concept and execution. My Krampus has certainly changed the way I ride and even the way I think about trail surfaces, but I have thought about how it might be even better with some squish. You build some pretty amazing bikes.

Just curious, but why a design with so much seatpost sticking out, instead of having the frame come up a little higher? Seems like there could still be plenty of stand over clearance for someone of your apparent height. I'm no bike builder or engineer, but I am a scientist, and wonder about the potential stress effects of the increased leverage of a greatly extended seatpost.

Walt said...

It's pretty common these days to use 400+mm seatposts with a lot of extension, so no, I'm not particularly worried about the leverage. I've done at least several hundred bikes with seatposts extended in this sort of range without trouble. But great question!

Spiff said...

Walt, have you had much time on the Maxxis Chronicle? I'm curious how they compare to the Chupas.

Walt said...

Spiff - not enough to draw any conclusions (I have only ridden that tire on a rigid singlespeed - hard to compare to a full suspension bike). I do know that it's quite a bit heavier (~1050g vs ~850g) and the tread pattern is (small knobs) pretty similar. I'd guess that durability is improved over the Chupas (which have been fine so far, to be fair) at the cost of extra sidewall material.

Andy D. said...

Thanks, Walt. I figured you knew what you were doing, but genuinely wondered. It's great to live in this new golden era of plus sized tires, multiple wheel sizes and widths, and the creativity and fun that such things seem to foster.

Walt said...

Indeed. The last 15 years or so have seen so much amazing (and fun) innovation!

Giff said...

Would these work? Zank has been using them on his aluminum frames and really likes them.