What happens when a mountain bike takes inspiration from a trophy truck?
The BREWser: an experimental belt-drive, gearbox, 190mm front and 184mm rear travel bike with a 62.5-degree head tube angle.
Adam “Prosauce” Prosise, the mind behind the BREWser, is a machinist at REEB Cycles who describes his riding style as “smashing into things.” He grew up dirt jumping and racing BMX in Iowa with his two older brothers, and he says Rule Number 1 was ‘keep up.’ Now, he’s a regular on the Big Mountain Enduro circuit and consistently places in the top third of the pro field on bikes he built himself.
The BREWser is a collaboration between Adam and a handful of willing friends: Chris Sulfrian, who taught Adam framebuilding; Tyler Brady, who helped with suspension kinematics; Steve "The Space Cowboy," who helped with engineering and aesthetics; and Pinion Gearboxes and Gates Carbon Drive, who helped figure out the whole belt-drive gearbox situation.
Details:
4130 Chromoly/7005 Aluminum Frame Construction
Pinion P1.12 gearbox, 600% range
Gates Carbon Drive belt system
RockShox ZEB 190mm 29” fork
Super Deluxe shock variation
Industry Nine Grade Hydra wheels. 29” F/R
Industry Nine stem 32mm
RaceFace Atlas Bars 35mm x 820mm
TRP DH-R EVO brakes. 223mm F, 203 R
Vittoria Mazza Enduro 2.6” tires F/R
OneUp 210mm dropper
Fizik Saddle
Oury Grips
HT Components pedals
Geometry:
Size: XXL
Seat tube: 450mm
Effective top tube: 680mm
Reach: 515mm
Stack: 660mm
Effective seat tube angle: 76 Degrees
Head tube angle: 62.5 degrees
Chainstays: 445mm
Head tube: 125mm
Axle to crown: 606mm
Offset: 44mm
Wheelbase: 1341mm
BB Drop: 23mm
Weight: "Doesn't matter where we're going." (It hasn't been weighed.)
The BREWser was built to be low-maintenance and indestructible, so the belt-drive and gearbox options were no-brainers for Adam, who fell in love with gearboxes a few years ago when he tried one at a bike park. REEB already builds belt-drive and gearbox hardtails, so Adam had friends in the right places, and the fact that the gearbox only needs an oil change every 10,000 kilometers fit right in with his vision for the bike.
Settling on the BREWser’s geometry was a bit more of a process. Adam has dialed in his preferred geometry numbers on several race bikes over the last few years, and has found that for him, longer and slacker is the answer. As he pushed the geometry a bit farther on each of his versions of REEB’s full suspension bike, he rode faster and faster until he and his coworkers had to redesign the rocker link to take more abuse. In designing the BREWser, Adam took the geometry numbers from his favorite bike, including his preferred 62.5-degree head tube angle, added a bit of chainstay length, and created a long-travel monster.
As for the material, the aluminum and steel combination was inspired by a trophy truck Adam saw at the Baja 1000 that had a raw Chromoly 4130 chassis with machined aluminum swingarms. Since Adam was already on a path of reducing unsprung weight by eliminating the derailleur and cassette, it made sense to keep the swingarms light and made of aluminum. The steel front triangle made for high strength and relatively easy fabrication.
| This isn't just a bike. It's a trophy truck. Suspension is meant to keep your tires on the ground and in traction. One way to improve that is to decrease the unsprung weight. Since I was already losing the weight of the derailleur and cassette, the aluminum swingarm helped keep that weight down.—Adam Prosise |
The most difficult part of the design was making sure there was enough belt clearance on the chainstay and that there was enough travel in the belt tensioner for a full 180mm of travel. Luckily, Adam said, Pinion had a full CAD package of information about those components, so with some extensive modeling and a bit of luck, it worked out.
The result is a bike to rival the Grim Donut.
The BREWser is about as custom as it gets.
I have a soft spot for raw metal bikes. This one has a gorgeous industrial look.
This bike has just the right amount of flair.
When it all came together, Adam was blown away by how dialed it felt, he said. He takes pride in everything he makes, but he's glad he didn't waste everyone's time, given that he leaned on a variety of people for help with the project. He wants to thank everybody who believed in the BREWser, and also those who didn't.
| Have you ever been on a downhill bike and wish it could be efficient uphill? Have you ever been on an enduro bike that you wish had a little more downhill prowess? Well this does both. It doesn't feel any slower uphill, and on the downhill, it’s straight comical how fast this thing can go.—Adam Prosise |
The BREWser in its current form likely won’t ever be for sale, Adam says, because those numbers are not for everyone and aren't the most marketable. Still, it is being used to develop a similar but less out-there REEB frame that we’ll likely see in 2022.
In the meantime, look for Adam on the BREWser at Big Mountain Enduro races, the TransBC (pending access to Canada), and any rowdy trails near you.
After riding the Zeb, I'm not convinced the boxxer is any stiffer. Plus that review pb dropped this week wasn't exactly flattering....
...I bet he weighed it and my guess is around 20kg.
I find it a bit annoying when reviewers slam bikes (like the Norco Shore) because they are 37lb which to me isn't stupidly heavy considering how capable the bike is.
www.youtube.com/watch?v=8DWpgP-KqiQ&feature=emb_logo
I'm poking fun at the new culture rising here in Utah- the economy is on fire and there are peeps in the late 30s and 40s coming up in managerial and executive positions, and they don't want to golf. Mountain biking (and road biking even more) is the new golf here, and every one show up at the ride bringing their ultra competitive business mentality to the trailhead. you have to stand around and admire everyones bike setup (and car that it came in) to try and impress everyone else before the ride starts. Since you work 50+ hours a week, not everyone can find time for fitness so they have to compete in other ways (of course some do, and I get dropped by 50+ year olds on the road rides all the time).
19.5kg
That's more my speed of Space Cowboy. Jamiroquai over Steve Miller Band any day.
DVO metric coil shocks can have the stroke changed just by swapping out the spring clip. I've just got a DVO jade x coil and done it.
Interesting that it can be used on the Rockshox. This might be useful info for anyone with looking to change stroke on their Rockshox easily!
Were you involved with producing or testing this bike?
How do you know?
Looks like it fits fine...
Haha just realised its actually your bike.
Did you use it to change the stroke at all or just what you had at hand?
Xups in race runs? Yeah that guy.
If I wasn't on a Guerrilla Gravity, I'd totally own a Reeb.
If anyone has the time and is curious to what level of nerdom the folks at Reeb put into their bikes, check out this vid from Jeff Lenosky youtu.be/_dNw6KO4Qd0
They go into detail about design and fabrication, setup, fixturing, tolerances, etc...aerospace manufacturing level of thought. They also go into why some mass produced frames may experience issues with wear or breakage. Pretty interesting stuff.
Also, take a look on the second hand market and don't be afraid, because these frames are basically indestructible
Get a G1, wild good fun. Do everything on it from shuttling to all day rides.
I'm 6'2 and have an XL. Crazy big but super stable though and starting to be able to corner it like I did a small bike. The ability to switch geometry and wheel sizes is amazing. Mullet is real for gravity tracks. I swap between 29 and Mullet alot.
EXT shock blows everything else out the water. Current build weight 39lbs. Robust.
Unless its SX, then it just exists for whatever reason.
Either way, for bikes that arent super light xc/downcountry machines, I've been convinced gearboxes are the way to go
I personally ride a 200/210mm dual crown, high pivot, dropper and dual bottle cage equipped downduro bike. Climbs well and descends like any other downhill bike.
Thanks for showing us something different AND exciting.
Boner +++
One question on bikes with geometry like this, how do you keep weight on the front wheel? I recently sized down from a 480mm reach to 460mm reach on a bike with 433mm chainstay and 64.5degree HA because I wasn't happy with the front end grip, I had before this gone for a 50mm steam over a 32mm. Both the stem and the smaller frame both helped a great deal on increasing my front end grip.
How does a 515reach, 62.5degree HA and a 32mm stem work then? Sure the longer 445mm chainstays help but still the differance in front and rear centers must be huge? Adam is obviously a more skilled and faster rider than I am and this is a custom frame for him (by him!).
First, most frames aren't stiff enough to keep alignment under max torque scenarios. REEB frames are some of the few that actually pass Gates stringent testing. When I raced cross, I hopped on one of the Raleigh cross bikes that was the factory Gates team bike. In the first lap, I skipped the belt multiple times. This was in a cross race. Nothing crazy steep, just putting power down out of turns. Since working for REEB, I have never skipped a belt on our single speed frames.
Second, I have put this through some of the steepest, hardest climbing we have in the front range of Colorado. Typically I run a 36t ring with a 50t in the back. The gearbox offers lower ratio than I typically run, and while standing in the lowest gear, I have never skipped the belt. Its not a problem.
This bike is a work of art- plus it’s nice seeing experiments in design that will get tons of real world use and abuse.
Sure is! Need to tell some of the authors\editors around here.
Do you need to dismantle the swingarm though, if you want to take the rear wheel off (i.e. take the belt off)?
Fair point about the wheel removal, but you need to faff with the belt tensioner at some point I imagine, hopefully enough belt length to get on/off the rear cog.
In short, from a practical standpoint it's a niche application that's several times more expensive (check out prices for sprockets and belts) to run than a standard chain. You do have to keep the system clean (and apply lubricant if it squeaks)
The biggest issue is that the primary market is commuters who can't be bothered to look after a chain, and figure there will be no maintenance. You can guess what happens when they get their first flat tire and have to properly align and tension a belt without mishandling it. And how often they clean it. Not to mention their expression when they find out what it will cost to replace it.
Good work sir , that’s a very nice looking bicycle you’ve made .
If you're tall enough, take it out for a ride even!
Ps. when is the wireless electronic braking arriving?
my size: reach 460mm and seat tube length max 420mm
costs? delivery?