Specialized Stumppumper Concept Bike - The Ultimate Pump Track Weapon

Feb 6, 2012
by Mike Levy  
 
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First Look
Specialized
Stumppumper
Concept Bike
WORDS Mike Levy

The popularity of pump tracks has skyrocketed over the last few years, with more and more of them popping up in not only backyards, but also at major events around the world. While banging out laps on a pump track is a great time, it doesn't take much for it to turn into a competition of sorts; inevitably the stop watches come out and riders are battling each other for the fast lap times. That, of course, quickly led to ever advancing pump tracks that grew is size and difficulty. What hasn't evolved much, though, is the bikes being used. Show up at any track, be it a local hidden gem or a world class monster like the one at last year's Kokanee Crankworx, and you'll likely see the majority of riders on their dirt jump bikes. But what if someone put some time and resources towards assembling a purpose built pump track weapon that is designed solely to rail berms and pump rollers? Specialized's Jason Chamberlain did just that when he set out to build the ultimate pump track bike. Behold the Stumppumper.

Specialized Pumptrack concept bike. Photo by Ryan Cleek.
  The Stumppumper concept bike is a purpose built pump track machine that weighs just 17.9lbs, but its light weight is only part of the story.

Focused intention: Chamberlain is well aware that the Stumppumper concept is a single minded approach to a niche aspect of our sport, but that didn't stop him from exploring the idea of a purpose built pump track bike. It's from exercises like these that he and Specialized learn about what works and what doesn't, and Chamberlain knows that what works on a pump track is the BMX approach. "It occurred to me that most pump track guys simply ride dirt jump bikes that are far from optimal," Chamberlain explains "If you want to go fast, then you need to look at BMX bikes, so that is where I drew inspiration. Rigid, stiff wheels, and light weight". The finished bike, weighing in at just 17.9lbs and using a rigid carbon fiber fork, reflects the single minded approach to looking for the fastest possible lap time. No, this is not going to be a bike for everyone.
bigquotesThe Stumppumper is intended for advanced riders only - it's fast, and twitchy like an F1 car. It's ultralight so it gets up to speed quicker, but may not hold momentum as well as a heavier bike. - Jason Chamberlain

Specialized Pumptrack concept bike. Photo by Ryan Cleek.
  Chamberlain built the Stumppumper up with Specialized's own BB30 carbon cranks, installing them onto the bottom bracket spindle in a drooping, offset postion that emulates a bottom bracket height 22mm lower than stock. With little chance of catching a pedal, low equals fast on a pump track.

Offset cranks: Carrying speed through a pump track's rollers and berms is key to a fast time, a feat that is always going to be easier to do on a bike with a low center of gravity. A ground scraping bottom bracket height is crucial to having a low CoG, but you'll never find an extremely low BB height on a bike that has been designed to excel at other types of riding. For example, a dirt jump bike will typically spin easier in the air if it uses a slightly higher BB, while a true mountain bike must also take pedalling clearance into consideration - neither fact making for an ideal, super low BB pump track setup. Chamberlain wanted to assemble the Stumppumper around a stock Specialized P.3 frame that uses 26'' wheels, but that would mean that the bike would use a rather mundane 301mm (11.8'') bottom bracket height.

The answer came to him in the form of installing the crank arms in an offset configuration, effectively lowering the bike's bottom bracket height by 22mm. The crank arms literally hanging down, or droop, from the BB spindle when at the 3 and 9 o'clock position. The result is an effective bottom bracket height of just 279mm (10.9''), nearly a full inch lower than the stock number. While the obvious benefit is the lower CoG, the offset configuration should also help to keep the arms from wanting to rotate as the rider makes their way around the track, likely relieving fatigue. Chamberlain claims that another advantage is the "balancing effect that the offset cranks have on your left and right legs, which stabilizes your body under high cornering Gs." While it may sound odd at first to run such a setup, one has to remember the Stumppumper is intended to spend its life on a pump track and nowhere else. "There is no drawback since tracks are smooth and you aren't turning your cranks - you don't risk clipping a pedal," Chamberlain explains when I questioned him as to if the Stumppumper's drooped cranks give it an odd sensation when pedalling. The drooped crank arms mean that they have to be set up for either left or right foot forward riders, otherwise the cranks will be angled up, defeating the purpose of the offset layout.

Specifications
Release Date 2012
Price
Fork White Brothers Rock Solid Carbon Fork
Crankarms Specialized Carbon BB30 w/ Home Brewed Components custom 25t chainring
Bottom Bracket Zipp Ceramic BB adapter cups
Pedals Specialized
Handlebar Specialized Carbon Enduro
Grips ESI Silicone Foam
Brakes Avid XX World Cup w/Shimano ICE 140mm rotor (rear only)
Hubs DT road front hub (wide flanges), DT Single Speed rear hub (wide flanges)
Spokes 32x 1.6/1.8 spokes with spoke head washers (preferred with 1.8 elbows)
Rim DT EX500
Tires Specialized Renegade 2.3, Control Casing
Specialized Pumptrack concept bike. Photo by Ryan Cleek.

Light, stiff build: While the Stumppumper's components are, for the most part, readily available to any consumer, Chamberlain has carefully chosen the bike's spec with its intended purpose in mind. The most obvious difference between this machine and a common dirt jump bike is the lack of front suspension, with the front of the concept bike sporting a White Brothers Rock Solid Carbon fork. The sub-900 gram fork employs 34mm diameter carbon legs that are bonded to an aluminum crown and dropouts. White Bothers offers two axle to crown length options to preserve the bike's handling, a short 425mm or 445mm length that simulates a suspension fork under sag, with Jason opting for the longer choice to keep the Stumppumper handling as intended.

After talking to Chamberlain about the project earlier in the season we had fully expected the finished bike to come complete with a carbon rimmed wheelset, but that isn't the case. The Specialized Renegade 2.3 Control Casing tires are inflated quite high for maximum rolling speed, so he chose to build the wheels with a set of DT's EX500 rims because they are more suitable for high pressures. A DT road hub is employed up front due to its wider spoke flanges that should improve wheel stiffness, while a wide flanged single speed DT hub is used out back. Chamberlain even took the extra time to use brass washers a the elbows of the 1.6/1.8 spokes, a recommended step when using the smaller size spokes in standard 2.0 flange holes.

The bike's drivetrain is about as exotic as a single single speed can get, especially considering that it isn't intended to be pedalled much. A set of Specialized's BB30 compatible S-Works Carbon crank arms are fitted up in the previously mentioned offset postion to imitate a lower bottom bracket height, and a custom made Homebrewed Components 25 tooth chain ring is slid onto the crank's spline in place of the stock spider. Light and simple, just like the rest of the bike.

Specialized Pumptrack concept bike. Photo by Ryan Cleek.
  ESI's Silicone grips are a popular choice among gram counting riders, but are also said to be quite comfortable and long lasting.

Form follows function, and the function of the P.3 Stumppumper is to be simple, light, and fast as hell. That's why you'll find a set of ESI's 50 gram Silicone non-locking grips on the Specialized Carbon Enduro handlebar, a favorite choice of riders in the know. The pairing of Avid's top of the line XX World Cup brake with a 140mm Shimano ICE rotor (the DT 240 Single Speed hub uses Center Lock rotor mounting) may seem underwhelming at first, but remember that the brake is likely only going to be used to slow down at the end of your run.

Photo by Ryan Cleek
  Specialized's Brad Benedict is a world class downhiller and all around animal on a bike. He looks to be getting on quite well with the Stumppumper on Specialized's private pump track.

Chamberlain and Specialized are well aware that the Stumppumper is about as a specific tool for the job as one can get. "It's a bit of a tough sell because it is so different. I am certain that it is faster in the hands of a rider who can capitalize on the design, though," Chamberlain continues "However, most guys are going to be more comfortable with what they are used to".

In short, it's unlikely such a bike would ever be made available as a complete package. But that's not to say that a dedicated pump track rider couldn't build up his own version, given that both the P.3 frame and all of the components are production items. The chances of you seeing sub-20lb pump track bikes that use offset crank arms at your local track are pretty slim, but I wouldn't bet against seeing Troy Brosnan or Sam Hill aboard such a machine come Crankworx time.

www.specialized.com
Photos by Ryan Cleek


248 Comments

  • + 122
 It`s a p1 all day long with other forks and goodies. Plus the bike industry is becoming like the auto, expensive like hell. Thousands of dollars for a bike, in the end it`s a bike that everyone should afford to buy, not if only u r a spoiled brat. have a nice day and keep it real
  • + 147
 It explicitly states above that it is a stock P3 frame with other production parts...
  • + 29
 It was intended to be available to the general public in the first place anyways though. The only way you can relate it to the auto industry is by comparing it to a concept car. Neither concept cars or this bike are likely to be made available to your average joe so you argument isn't very valid in all honesty.
  • + 30
 So pretty much all it is, is a p3 with s-works cranks and a carbon fork?
  • + 28
 @mtbforlife4 you betcha. I personally think its a load of bull, since my dirt jumper is perfect for flowing through a pump track, so I don't see the point for this...
  • + 9
 I think the main point is the rising cost of bikes and parts seems to be more than the cost of development and materials etc.. the truth is cycling is becoming more popular and we're all hooked so they (the man) knows the prices can climb.
  • + 7
 Well what they said in the beginning of this article is that they wanted a porpoise built pump track bike, not a dirt jumper. I thought that was going to mean a totally new frame design. Turns out that in an attempt to make a pump track bike, they successfully made a really really light badass dirt jumper that happens to ride good on pump tracks. Haha it's pretty sweet though and a really cool idea.
  • + 11
 This is probably not a bike that you would ever build up for yourself, but if you were at a pump track and someone said, "Here, take it for a spin", wouldn't you want to rip a few laps on purpose built, 17 lb, PT Ripper? I know I would.
  • + 2
 Would never own it unless it was one of a fleet of and i'd somehow got mega ££££. As Sniggled says, I'd love to have a blast!
  • - 3
 Why would they call it a "Stumppumper" when it in fact has NOTHING to do with a stump? Why not like P.pump or something? I know that sounds horrible, but at least it has something to do with the niche riding they would be doing.
  • + 6
 If you had your own backyard pumptrack or rode pumptrack several times a week you might consider a pumptrack specific build. I know somebody who has a purpose built pumptrack bike for instance. You can see why specialized have bothered to put one together. If you look at the leader board at many pumptrack events the lap times are so close that a bike like this over a normal DJ set up could be very beneficial...

Also, if I was in charge of building this bike it would have KHE mac2 tires. Shave a bit more weight. The knobblies are unnecessary... Smile
  • + 5
 The Stumpjumper is Specailized most iconic bike. It represents a lot of first for the company, first mass produced and affordable mountain bike, first to use FSR; there's even one on display in the Smithsonian Museum. Its like their flag ship bike.
  • + 5
 It's not like they're actually going to produce this bike. It's just a play on words...
  • + 9
 It's pretty simple to me, I don't know why everyone is complaining, it's a super cool idea. Crankworx created the 'world championships' for pumptrack racing, so if you were a big company and could make a world championship machine so simply that would be better than anything else for it, why not do it? Very cool article, I enjoyed it. Now, is anyone going to buy this? Probably not, and they know that...will you see alot of riders of them at crankworx? You bet. I just hope they have one to demo at the sea otter pump track!
  • + 0
 Stupid name, but a legit concept bike. I'd like to try it, without the plastic parts and stiffer wheels. Should also have 160 mm cranks. Lowering the cranks is nothing new single speeders have been doing it with eccentric bbs. But perhaps this is the first good use of BB30, since otherwise it is a crappy, creaky design. Don't attempt to build a bike like this or Mike Sinyard will sue you.
  • - 1
 It doesnt have an eccentric BB. He's just fitted the crank onto the splines wrong; basically he's tried to make an assembly error the main feature of this "concept" bike.
  • + 1
 People need to stop giving specialized crap for making this bike! It's made for people who want it and have the money to buy it. Just cause its hell expensive doesn't mean it shouldn't be on the market. Stop bitching and start riding!
  • + 3
 But it's not on the market, nor will it probably ever be.
  • + 1
 Holy shit. The bike is on the market. It is a stock P3 frame with readily available parts. You could go out tomorrow and build one of these if you wanted to. People, please stop being so ignorant.
  • + 4
 agreed with bubbaleech, were trek, giant, transition or any other company going to do this they wouldn't get near the hate this is getting... this isn't for your still in high school dirt jumper/park rat. This is a purpose built machine much like any other "race" bike.

if you take a look @ bmx racing/parts. Many parts and/or frames have rider weight limits because they are so light and they are like that for one reason, to go fast.

and like was said in the article, were i to have the cash, i could go over to my local bike shop and have one of these spec'd out with in 1-2 hours. The parts are out there, just need the coin to pay for them all.

Salute
  • + 0
 "This is a revolution" Steeve Jobs says...
  • + 2
 its not made to be a production bike, so theres no need to complain about how expensive it is. they know no ones going to drop that kind of money on a bike to only use on the pump track. but specialized has the money and resources to do these kinds of projects, and by doing this they learn things that they can use on their production bikes. this is just how innovation happens. and while none of us are ever gonna own one think about how much fun that'd be to ride.... looks damn fast
  • + 1
 all you need is a small frame, fast rolling tyres and a rigid fork, oh and no chain, lol. my identiti dr jekyll works fine. also, these parts cost nowt to produce, the only reason they cost so much is because mountain biking is a niche sport, usually undertaken by men who like kit, and will pay for it, how come they can afford to offer such huge discounts on last years bikes, its as if they didn't expect to get that much in the first place?
  • + 2
 because floor space is more valuable to the shop than making a huge profit of it. Remember shops dont pay NEARLY as much as we do. Having worked in my LBS for a few months for my co-op placement i know what its like to have a bike sit and have no one want it. But they price the bikes they way they do cause people DO buy them trust me, even during the slow season most shops in the area will sell 1-2 bikes a day on average, and closer to Christmas and February its around 4-5 on most days. Offering huge discounts on last years bikes its just clearing them out for the new model year. The auto industry has been doing the same thing since the 50's and 60's.
  • + 1
 I wonder if these projects are more so to inspire interest for the P3 frame in general rather than for the interest in this specific model, a sort of marketing plot.
[Reply]
  • + 43
 WHAT THE HELL YOU GUYS DON'T UNDERSTAND IN CONCEPT BIKE? This is simply a project they had in mind, they might not even sell this, they were simply trying things out. How do you guys think we have double-crown? Hydraulic brakes? Gears? Rear shock. It's all about creating new ideas. Putting ideas on the table. Brain-storming..
  • + 1
 You have a point there but... can avoid be a little disappointed to see that they didn't make anything new other than combining some parts that we don't usually see out there... But, still love the final result! One of those bikes that rationally I wouldn't buy but... definitely want it!
  • - 1
 it clearly says it will be released in 2012... So it's not that much of a concept anymore... but I don't see any problem with releasing this bike.
  • + 3
 all it is is a bike that only two types of people will have. sponsored racers advertising the product and spoiled ass rich kids that think the product will make them a better rider then there skills will. you can put a pro on a NEXT 29" mountain bike from walmart on the same track as a rookie rich kid on this bike and if they raced the pro would still stomp him. i love having nice bikes and components not only for effectivity but for looks as well but if i had my choice to sit on the seat of this bike or ride a stock p2 all day at the pump track i would ride not flash!
  • + 0
 This is exactly the kind of bull you hear everytime Shimano and SRAM introduce new technology into their top level line ups. "Oh its only for pros and spoilt rich brats!" "I'm never going to be able to afford that, why do they bother?!" "Oh now my bike is completely obsolete, why don't i just throw it in the bin?!?" Yeah and while you're at it, you can throw yourself in the bin too with your retrogressive ideas about the bike industry.

Seriously if you guys were in charge, we'd still all be running triple cranks on rediculously heavy freeride bikes with sh*t suspension design and sh*t tyres and f*cked shocks and forks.

The point being all of these "NEW", "CONCEPT" designs are there to make the bike industry more accessible and easier to make use of. IT MAKES BIKES BETTER! TRICKLE DOWN!!!! All of these kinds of tech will be available in 5 to 10 years at an affordable level and you won't be complaining about it then! This is why Shimano (for example) will be releasing shadow plus into their lower level groups in the next couple of years - so we don't all have to shell out £150 for a new derailleur!

Alternatively you can just bury your head in the sand and ride around on a 20 year old heavy as f00k steel XC frame (which will snap) with 15 gears, crap tyres and rims, canti lever brakes and no suspension. Enjoy.
  • + 1
 Amen to that.

Oh and Ninjanate, I'm not spoiled nor rich; have you seen my bike? (I don't smoke, I didn't go to parties every weekend, and I sold my 5D mkII with 3 L lenses) Everyone can make the kind of money to buy the most expensive bike, it's just about priorities and how much you're willing to do so.

Don't hate man.
  • + 1
 I'm not a rich kid either. Look in my profile and you will see I am sporting some of the best bikes available and rocking a brand new truck I bought with cash! You know how I did that. I spent 6 years working my ass off in the active army and did 2.5 years serving my country in Iraq! You wanna talk about priorities. All I am trying to say is I love riding. Period! I'm all about the progression of the sport and components. All I'm saying is people now adays are way more into what the brand name of there bars are then actually riding there bike and just having fun!
  • + 2
 If a good looking handlebar makes them go out, ride and have fun with their friends, then what's the problem? I'm sure that kids, even spoiled ones, don't build their dream bike to leave it in the garage.

We worked for our bikes and we know what they're worth. Kids may not do that, but it's not at puberty that you start thinking about what money is anyway... You just want the best stuff so you can impress your friends and get the prittiest chick.
[Reply]
  • + 24
 it's things like this that bring progress to the bike industry i reckon. good work spesh
  • + 5
 Thats exactly right! Things like hydraulic brakes, when they first came out they would have cost a fortune. The guys that have lots of money buy these things before anyone else and then the company can afford to make more and more therefore making it cheaper (or something along those lines), then everyone does it and it is affordable for everyone. Its like hydraulic gears that are coming out, they wont stay £300 for a derailleur forever, give it a couple of years and they will be much much cheaper. You see the same idea everywhere, tv's washing machines etc etc
[Reply]
  • + 24
 readers have to under stand that this is a concept. not a production model. Stop complaining and take it for what it is.....
[Reply]
  • + 14
 Nice concept but frankly lacking some attention to detail. It's a pump track bike so: Why the drivetrain? Why the seat? Is the brake really necessary if you are only going to use it to get out of the pump track? Use you feet to stop?

Further improvements:
- Remove the chain and rear cog and make bb bearings run less smoothly so the crank arms dont spin as much.
- Make a frame without a seatpost and saddle
- run a short fork 400mm like on a trials bike and built a frame around it so you get the geometry you want. You'll end up with a REALLY unique bike instead of a tuned dirtjump bike which is what we have here...AND even lower weight
  • + 4
 I disagree about dropping the brake, because if you dont want it, you can take it off and only have an extra couple of grams in frame tabs and in a disk hub. but completely agree with you on everything else. would be sweet to see a start from scratch design carbon frame with no seatpost or saddle, super tight geometry and sold with two left hand cranks (no drivetrain.) guess it would end up looking a little like an Onza trials bike...
  • + 6
 You still usually need a pedal stroke or two to get started - that is why we kept the drivetrain. Though there are some rumblings of making certain comps chainless to reduce cheater pedaling.
  • + 8
 Seatless - I like that - like the Monty Carbon mod trials bike. For now, I put on the lightest thing I had so you at least had somehwere to sit between runs. It's also nice to have a rear brake in case you come in too hot and need to scrub a little speed.
  • + 2
 A BMX is the best improvement surely?
  • - 1
 bigburd; I couldn't have said it better myself! We clearly have our brains switched on today!
  • + 6
 You want the chain because it gives you tension, if you've ever ridden without one you know what I mean. I think that the biggest thing they missed out on was making the frame out of carbon. If its purely for pump tracks its not going to need to withstand any serious impacts, so they could get it seriously light by carefully controlling the thickness of the tubes.
  • - 2
 Seatless won't work - you use the seat to hold the frame in the right position with your thighs. Take the seat off and you will find it rides worse. Someone made a BMX once that had no seat as they thought the seat was redundant and they found out they were wrong. I do agree with bigburd, if you want the ultimate pumptrack weapon, BMX is it.
  • + 2
 I beg to differ about the seat. Look at BMXers these days - seats by their ankles and still doing barspins!
  • + 2
 yea but the seat is CRUCIAL to cornering technique.
[Reply]
  • + 15
 If you need to beat someone on a pump track, just start drinking more beer.
[Reply]
  • + 15
 Stumppumper - sounds like some fetish porn site.
  • + 20
 Amputee erotica?
  • + 0
 hahah classic
  • + 5
 I don't know what that video is of, but I sure as hell am not going to click on it here at work after that brief conversation Smile
  • + 0
 Yeah, that's probably best. Especially if you are at work or in the vicinity of any children or having dinner with your nan or at sunday mass...
[Reply]
  • + 8
 Interesting article. I assumed that this was just a concept bike, until I saw a release date. talk about a niche market! getabmx.co.uk
  • + 3
 It is just a concept - not really intended for sale.
  • + 0
 But it says release date: 2012 ?
  • + 0
 Not sure why that is in there.
  • + 1
 It is in there as to when it was made - the current year is 2012. But like Jason said it is not going to market.
  • + 0
 OK! Thought it meant that 2012 was the release date for the bike. n.m!
[Reply]
  • + 6
 I cant beleive how much all you guys are crying about this bike. You clearly didnt read the article you looked at the pics and started bitching. Props on sounding like a bunch of highschool girls.
[Reply]
  • + 5
 "White Bothers offers two axle to crown length options to preserve the bike's handling, a short 425mm or 445mm" Actually we have three currently (425, 445, and 465mm) and there is a fourth on the way (490mm). Cheers
[Reply]
  • + 8
 Should be called the P.Pumper!
[Reply]
  • + 4
 there's nothing 'concept' about this. Anyone can get a stock p3 frame, fudge some carbon cranks onto it and fit a carbon fork.
The reason most people use dirt jump bikes for pump tracks is because they're perfect for it. Pump tracks are built around the bikes, not the other way around (seeing as DJ bikes came before pump tracks did).
  • + 0
 Very good point well made.
  • + 0
 agreed...all they did was turn a DJ into a damn bmx...nothing "new" about the concept
[Reply]
  • + 4
 I think people are looking at this wrong. Don't look at it as a new bike (we all know its just a P3), look at it as an addition to the P range, if not just a variant of the P3. I would buy one as its a pretty good build, I don't know how much it will cost and get a feeling it probably will be pretty damned expensive with the S Works stuff but still, I like it and think it looks pretty good, and if I had the money would seriously consider buying one!
[Reply]
  • + 3
 You actually just built a BMX Cruiser. Cruisers originally had 26" wheels back in the 70's through the early to mid eighties. As tracks got more technical, with more jumps and closely spaced rollers, more people switched to 24" wheels to get more "pump" and precise control. A smaller diameter wheel allows the bars to get lower and closer, horizontally, to the bottom bracket. This gives the rider more leverage against the pedals for more "pump". Leverage is also increased by having a long font end and short rear triangle. The smaller the wheel, the shorter the rear. Increased stiffness of shorter spokes helps too.
  • + 1
 Props on trying to invent another "new" category though! It worked with the whole "DJ" bike thing. You can charge twice as much for a product that works half as well and breaks twice as often.
  • + 4
 I meant to write "vertically" not "horizontally", up there. I just woke up. Kind of ruined my whole smarty pants comment.
[Reply]
  • + 5
 So Fox and Specialized have PRIVATE pump tracks, that 's great, what about building a real bike park for everyone else in the bay area?
[Reply]
  • + 3
 As far as riding with the offset cranks... you could ride with them in the standard position and when you get to the pump track, take off the left arm and set it in the offset position. The tools would easily fit in your pocket or under the seat. Pretty damn light, nice "concept".
  • - 1
 Offset cranks is the dumbest thing I've ever heard. What a joke!
  • + 2
 Not really. It doesn't influence the pedal stroke nearly as much as you would think. In fact, I would still say the bike would be maybe 75% as efficient for normal riding. It would seem the handling benefit easily out guns any downside. Especially considering that offset cranks lower the 'effective BB' without adding any additional pedal strike

I actually inadvertently made an 'offset crank', I was just messing around, jumping an old BMX one day, and gradually twisted the one-peice crank about 20 degrees. It didn't ride half bad, in fact I didn't even notice immediately. Honestly. It's no big deal.
  • + 0
 You do notice it and it feels bloody awful!
[Reply]
  • + 4
 in the uk we have the DMR pump track challenge about 5 times a year and with £500 for first im sure someone could make this bike and its costs work for them
[Reply]
  • + 5
 Put some 831 s on it and that would look sooooooooooooo good Big Grin
  • + 22
 Then it would be a regular P.3 lol
[Reply]
  • + 2
 a dont care about the dimesions and statistics about this concept bike am goin to get one for the summer to got to work on then as soon as i finish work playtime for a wee bit every freaking day trust me watch this space.
[Reply]
  • + 4
 Very nice concept! Again, they may not ever make this, but you can basically build it yourself! BIG RED S FOR LIFE!!!
[Reply]
  • + 1
 Bring on the hate, but I honestly don't think this is practical for many people, despite being light, and probably riding nicer on pumptracks than most dj's, I'm going to make the assumption that most people would get far more use and value out of a dirt jump bike that can ride more than one discipline extremely well. I'm sure it will work really well for some though.
  • - 1
 Just look at the "offset crank" and the justification behind it - total joke.

April fools day isn't until 2 months time!
  • + 1
 You should perhaps try the crank set up before dismissing it. Some very fast people have said it works. You are welcome to try it if you are ever near Morgan Hill or at Sea Otter.
  • + 3
 Really? I have a bmx with 48 spline cranks and a pump track nearby, however I've never thought of deliberately misassembling my cranks and I know loads of engineers who ride and they have never done it either.

I've ridden with bent cranks before and TBH I never found it an advantage.

Surely you should just be running a frame with a lower BB height or 24" wheels?
[Reply]
  • + 1
 Nothing like putting stuff together with only a vague idea of the final outcome. It's funny how some of those things actually work out pretty well. Now hook me up with a job as an engineer so I can frankenstein a bike with you haha.
[Reply]
  • + 1
 GREAT......................ANOTHER CASH GRAB. At the end of the day the big S now wnts more cash for yet more SPECIFIC riding bikes. I guess they want me to buy e quiver of ONE USE ONLY bikes. A DH, track, all mountain, XC, psycho X, time trial, urban, 29ers and now there is a street/park/jump bike....now not good enough for a pump track so we need a stumppumping money grab.
  • + 4
 It's almost like they run a business which needs to make a profit!
  • + 0
 No!! Evil business trying to turn a profit, give us variety and stay afloat so we can have bikes to ride. Evil, evil, evil, haha.
  • + 2
 i will stick to my all mountain killing machine thanx
  • + 0
 Do the words concept mean any thing to you? Even if they were going to produce this bike I'm sure they would simplify it and make it affordable. Who knows maybe the coolest thing to come out of this is a quick adjust crank that you can ride normal to the track then off set for your run; then back to normal for the ride home. It's called R&D and Specialized was cool enough to let us see how it's done.
  • - 1
 "Who knows maybe the coolest thing to come out of this is a quick adjust crank that you can ride normal to the track then off set for your run; then back to normal for the ride home."

AHAHAHAHAHAHHA!!!

If it's so cool then how come you can do it with nearly every crank ever made? Like square tapers or Profile BMX cranks? 48 settings - woohoo!

The reason no ones done it before is its a bloody stupid idea which is also known as an assembly error!
[Reply]
  • + 2
 "but you'll never find an extremely low BB height on a bike that has been designed to excel at other types of riding."
Right Razz

www.specialized.com/us/en/bc/SBCBkModel.jsp?spid=39175&menuItemId=0
  • + 0
 christ alive, my old riding buddy had one of those for 2 years and i never noticed how horrendously low that bb was. like, i knew it was low, but... Eek

no wonder the thing that finally convinced him to sell it was taking it to a skatepark.
[Reply]
  • + 2
 Nice concept. While I would never buy one if they did ever start selling them, I would love to test one on a pump track to see exactly just how much difference there is compared to my dj.
[Reply]
  • + 5
 8 kg ?? am i right ? thats awesome
[Reply]
  • + 1
 It's cool to see it and it's definitely worth Specialized's effort. I'm sure we'll see something like this at big pump track races. A lighter, lower, rigid dirt jumper really is the ultimate pump track bike. I am glad that it's not going to be available to the public. If you have enough money to have a carbon specced bike for every subcategorization of mountain biking, then you should spend more time with your family and give more money to charity.
[Reply]
  • + 1
 I feel like theres places to made it lighter. if its a pump track bike, why not make it chainless? anyone who is good enough to get this isn't going to need a chain.
and chop the seat tube and drill the steerer.
[Reply]
  • + 2
 Ultimate Weapon? don´t thinks so... horrible crankset... in my opinion, there are best components out there than those showned in picture
  • + 2
 I'd love to hear what parts you like better and we can discuss.
[Reply]
  • + 1
 Anybody have a phone number for HomeBrew Components? I ordered and paid for a chainring and its been 2 months now and I haven't received anything or gotten a reply via email.
[Reply]
  • + 0
 So this is more or less a setup rather than a new production bike . I can not understand why companies persist in making the same geo and trying to change parts to improve what can't be fixed . I in the article it states that most of us are using dirt jump geo's at pump tracks. but the p3 is a dirt jumper . So how does changing parts make it not ? Also dirt jump geo's are designed for pumping are they not ? Head back to the drawing board and design a new frame or just claim setup and not a new bike :/
[Reply]
  • + 1
 Amateurs don't use Stumppumpers Brian, I've the seen the way to ride kid, you've got a heavy foot, you'll blow your self to pieces"
[Reply]
  • + 2
 When I started reading, I just thought it was done to be a joke. I think it's pretty funny, but kindof cool at the same time
[Reply]
  • + 1
 If you want a bike that pumps good you need the center of the BB higher than the center of the axles...which is not a P bike right now at least.
[Reply]
  • - 1
 Just wondering, why use a drive train if:
A. It's a pump bike (I've never ridden pump tracks, but I assume they don't pedal)
B. Has anyone ever offset their cranks? I have (by about 3 splines on 48 spline cranks) for laughs, and at a certain part of the revolution, it becomes extremely hard to pedal.

So why put a drive train on it? Could've saved a lot more weight. Wink
  • + 1
 Chain for little cheater pedal kicks, and offset cranks because you dont actually pedal.
  • + 1
 I see, but aren't cheater pedal kicks, well, cheating? Razz
  • + 2
 Have you never borrowed an answer from the dude sitting next to you during a test? I would still say you earned your grade.
  • + 7
 You still have to get the bike to the pump track. No one wants a bike that you cant ride down the road. Isnt a bike without a drivetrain just a scooter?
  • + 2
 little "cheater" pedal kicks are sometime nessecary for positioning yourself on the bike and pumping.... you wont even notice your doing them. try riding with no chain to see what i mean
  • + 2
 Normally you put in a couple pedals strokes to get started.
  • + 1
 @Dirt-Street-Park "Has anyone ever offset their cranks? I have (by about 3 splines on 48 spline cranks) for laughs, and at a certain part of the revolution, it becomes extremely hard to pedal."

Funny that!
[Reply]
  • + 1
 I think P.3 Evo is more appropriate. Offset cranks are pretty genius out of the box thinking. always wanted to do a super light build on my P.3.
[Reply]
  • + 1
 How Does that BB30 bottem bracket work??? Is it concentric and you could use it to have a rear offset to have a shorter effective chainstay length??
  • + 1
 It's not a concentric BB.

They've just mis-assembled the crankset (not lining up the cranks properly at 180 degrees on the splines) so that they point down at the 4 and 8 o'clock positions.

Bottom bracket is standard BB30 that you can buy in any store :-)
[Reply]
  • - 1
 Have fun trying to do anything with this bike but pumping yourself at the "track". Who cares about pump tracks and times etc? We more interested in jumping and race tracks. Build up a 16 lbs bmx race bike and destroy this toolbag at any track, even a pumpy track.
  • + 1
 Indeed. I ride my cult deathrow (23 pounds complete) at the pump track and it feels better then my dj hardtail.
[Reply]
  • + 2
 if this bike is for pros, why not make it drivetrainless, save weight and make you more skilled
[Reply]
  • + 2
 6 months too late big'S. check out the pumptrack NS majesty i built last year Smile
[Reply]
  • + 0
 haven't read much of the other posts - but why do I / or anybody want to have a carbon fork/cranks on a pumptrack bike?

"normal" bikes with normal prices would be of more use for anybody
[Reply]
  • + 3
 I like the dog in the first picture!!!!
  • + 3
 that dog is fantastic.
  • + 1
 You should see him in real life. His head is as big as an aligator's. And he has this amazing purple-ish hue to him. Most unique dog I've ever seen.
[Reply]
  • + 3
 Pump track bike with a drivetrain? Surely that's cheating?
[Reply]
  • + 2
 Really guys... back on topic here... that dog is REALLY COOL!!! Smile
Basset Hound/Pitbull?
[Reply]
  • + 1
 When I first saw this on the home page and read the name I thought it was for sure a joke. Seems like a pretty legit article, interesting idea. Very much a niche market!
  • + 6
 I think it's a pretty cool idea, but it's a bit overkill too. Most people buy a jump bike to do it all pumps and jumps. Unless you have money to throw away why would you buy a extra "pump bike"? Unless you were a pro pump rider of course haha!
  • + 8
 For me, the whole point of building and riding pump tracks is that you use your cheap jump bike to have fun riding with friends while improving your skills...
Making a serious sport out of that is just killing the fun "factor" Frown
  • + 1
 I think it has a market for people who want to use pump tracks to improve bike handleing skills and fitness, but don't have much interest in dirt jumping or big air. I have a DH bike and an XC rig, neither is really that good on a pump track. If they can make ~$500 rigid trials bikes overseas, I'd like a similarly priced semi-light good pump track geo rigid to train on a pumptrack. I think exploring pump track geometry is a win win all around, but mega $$$ ultra light bikes seems like BS.
  • + 1
 Buy a jump bike for 1/2 the price then you can do jumps and pumps....
[Reply]
  • + 1
 nice idea but it has a brake www.facebook.com/GravityProjectGP we were there first ,spesh only had to ask us and we would have told them what they need to know
[Reply]
  • + 1
 idk about this, i like riding all kinds of genre's with my p2, street, park dj. but if someone would buy this, the would be stuck with just riding pumptracks,
[Reply]
  • + 1
 Those grips are not "long lasting". I have used mine for two rides and I am already creating a good thumb groove..
[Reply]
  • + 1
 Has anyone heard of the Red Bull Mini Drome? This would be perfect for that
[Reply]
  • + 1
 low bb, just run 24's! lol, think my pump track bikes better. Smile

www.pinkbike.com/photo/6428306
[Reply]
  • + 1
 cool idea.. i mean the p3 is sick as is. this is just way too specialized (pun)
  • + 1
 and a horse with a cow suit on is still a horse.. stumppumper? i beleive its a p3.
[Reply]
  • + 2
 that's not brad benedict.... it's clearly matt west from adelaide....
[Reply]
  • + 1
 if its gonna get to pump track specific bikes, i want world cups and champs Smile
  • + 2
 The have unofficial World Champs for a couple years now, right?
[Reply]
  • - 2
 Why make something that was already really suited to pumptracks even more specific? Would have much rather seen the time and money spent trying to adapt something like Josh Bender's Karpiel to pumptrack use! Now that would be an achievement Razz
[Reply]
  • + 1
 this is the test bed...your input will shape their decision on how expensive to make the production model...
[Reply]
  • - 2
 "The answer came to him in the form of installing the crank arms in an offset configuration, effectively lowering the bike's bottom bracket height by 22mm. The crank arms literally hanging down, or droop, from the BB spindle when at the 3 and 9 o'clock position."

BAHAHAHAHHA I just read about the offset cranks! I.e. he deliberately put the crank onto the spindle wrong.

What idiot had a brain fart and came up with that!?!
[Reply]
  • - 2
 It seems like a pretty lame idea for some to put these components on a p.3 frame, but I like to see it as new beginnings for a sport. Now that Specialized opened this idea to the bike industry, there might be more bikes to come that fit this genre of the "pump-track bike". I hope to see more of this coming in the future because nothing is more fun than a good pump track.
[Reply]
  • - 1
 I would have expected more from company like Specialized, heres a better idea why not make a mountain bike with a sealed drive? I could show you how its done!!
Was this idea done when the designers were out to lunch?
  • + 2
 Precisely - all my good ideas occur when I am at lunch, riding. Smile
[Reply]
  • + 2
 All that weight saving but 10lbs in hair...
[Reply]
  • + 2
 If you build it, they will come.
[Reply]
  • + 2
 Why a bike especially for pumptracks? What's next, a bike only for 360's?
[Reply]
  • + 1
 I think you'll find the ultimate pumptrack weapon has 20" wheels and is called a BMX...
[Reply]
  • - 1
 Looks like a specialized employee had a spare frame laying around with some uber nice parts, put it all together, and are debating about marketing it as if it were a bad april fool's joke.
[Reply]
  • + 1
 Change all carbon parts(especially cranks and fork) and it's just perfect dirt-4x machine.
[Reply]
  • + 2
 fantastic dog
[Reply]
  • + 1
 Eww wast of money us a rigid 24 or 26
[Reply]
  • + 1
 cool bike could use like dj2 bombers
[Reply]
  • + 1
 Anyone know the possible price of this? Razz
[Reply]
  • + 1
 i don't get it why buy a separate bike for the pump track
[Reply]
  • + 1
 I want, I want, I, want!!!
[Reply]
  • + 1
 soooo its showing you what you could do to a p3 if you already have one
[Reply]
  • + 1
 Can anybody tell me what pedals those are ?
  • + 1
 Those are the new Specialized Bene pedals. Green color and Ti spindles are custom
[Reply]
  • + 1
 i think specialized should just send me that frame
[Reply]
  • + 1
 I would use this for street riding.
[Reply]
  • + 1
 looks ordinary jump bike but because it's Specialized it must be good!
[Reply]
  • + 1
 Specialized Stumppumper. Absolutely specialized.
[Reply]
  • + 1
 Didn't somebody have this like 2 months ago? Razz
[Reply]
  • + 0
 another crappy frame from specialized this whole true about specialized and mass taiwan production bleeee puke>
[Reply]
  • + 1
 That's a light bike ! Smile
[Reply]
  • + 1
 The frame looks pretty dam good to me
[Reply]
  • + 0
 errr off set cranks?.............
so the bikes gonna pedal like a pogo stick
[Reply]
  • + 1
 I'm curious about the pricing...Like waaaaaay too much
[Reply]
  • + 1
 i would love to ride this
[Reply]
  • + 1
 wow....OO
and also like green color on p3 frame)
[Reply]
  • + 1
 i hate to say it but the name sounds...
[Reply]
  • + 0
 "purpose built pump track machine" - That is the dumbest thing I have ever heard.
[Reply]
  • - 1
 I've never seen anyone on a bmx go as fast as a dirt jumper through a pumptrack.
  • + 3
 open your eyes then
  • + 1
 a bmx bike cant keep the momentum of a 26 inch wheel, or pump through a roller as quickly. those guys look fast cuz theyre putting twice as much effort manualing through rollers youd fly through on a bigger bike with longer reach so your bike moves forward instead of up and down. i wanna ride that bmx track though
[Reply]
  • + 0
 sick looking bike and i like the name of the forks: White Brothers Big Grin
  • + 1
 Dude, white brothers are quite famous!
[Reply]
  • + 0
 should be called the pumphumper
[Reply]
  • + 0
 I don't like the fork, but otherwise a nice bike!
[Reply]
  • + 1
 will mitch ropelato be riding this at crankworx pump track challenge this year?
  • + 1
 No, he didn't. Funny that!!!
[Reply]
  • + 1
 17 pounds!!!! Wtf
[Reply]
  • + 1
 nice trials bike
[Reply]
  • + 1
 no one will buy this
[Reply]
  • + 5
 It's just a concept to explore what is possible, what works and what doesn't. It was never intended for sale.
[Reply]
  • - 1
 riding pump with a rigid sucks at all. sorry.
  • + 1
 tell that to millions of bmx'ers rigid forks are awesome for pump/bmx tracks, just my opinion Smile
  • + 1
 for bmx - agreed. but nothing else.
  • + 2
 well i'd have to just agree to dissagree Smile i ride rigids on my NS majesty built for pump/bmx track street an park. i just didnt see the pont in having a couple extra pounds on the bike slowing me down
  • + 1
 damn skippy! rigid all the way for a park/DJ/pump track rig. rigid forces you to ride smooth, which is pretty good to learn how to do.
  • + 1
 yes of course, but it also ruins your wrists...
  • + 2
 yeah OK.....
[Reply]
  • - 1
 holy wide bars! what are those like 38 wide!?
[Reply]
  • - 2
 Do not make it rigid! It's just not right! Otherwise I like it.
  • + 0
 Just put a super light suspension fork on it.
  • + 1
 100% agreed
[Reply]
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