# Want to build a dirt-jumper 29'er



## 2tallrid3r (Aug 24, 2009)

*I am cross-posting this just to confirm what the 29'er folks told me... which is basically that building a 29er for Dirt Jumping is a bad idea. Just wanted to get the freerider's thoughts on this to confirm if that is true..*

So i have been spending a lot of time lately at a dirt-jumping track at the Golden Bike Park in Golden Colorado with my 11-year old son... my kid has gotten so good he is going to start competing in Resort 4-cross this season. Here's a pic of the kid in action...


























As for me, I have been trying to keep up on my 23" fully-geared 29'er, and needless to say it isn't quite cutting it. I can do okay as I have a lot of motocross background. I can clear quite a few of the jumps, but completely absent of style and grace of any kind. it doesn't help that everything about the bike geometry is wrong. I love the 29'ER wheels but I need to start over and build a bike from the ground up to keep up with my son... It also doesn't help i am really tall (6'6") and about 230 lbs to begin with, so this could be a daunting task...

What I am considering is a couple different paths... buying an inexpensive single-speed 29'er with a smallish frame and building up from there, or starting with a custom geometry-corrected for 29' wheels frame built by Salvagetti's in Denver...

Some basic criteria for the build... probably 20mm thru axle up front, long travel front suspension (at least 130-150mm travel), bombproof hubs, at least 2.25 tires front and back with aggressive tread, and that's about it. These are pretty simple bikes with a very simple purpose... bombing down smooth trails with big jumps.

I found a few posts on pinkbike about what a bad idea it is because of the risks of taco'ing the bigger wheels under load, but I think 29" wheels have come really far in a short amount of time and are almost as bulletproof now as 26" wheels. So my question is... any of you guys done this already? If so, any tips or tricks on parts, frames or geometry?

By the way, there IS a 29'er dirt-jumper out there that I have found, but it is a BMX bike, which is quite a bit different... the PK "Big Ripper" shown here:










What I envision building is something like this:

Niner's Concept Dirt Jumper Bike


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## SHIVER ME TIMBERS (Jan 12, 2004)

honestly, I wouldn't build a 29er jump bike...but that is just me because I weigh too much.

the spokes are extra long making the wheelset weaker...and even yourself said the bike is hard to throw around and have style. 

Get yourself a 26 inch bike and it will be easier flickable in the air....


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## 2tallrid3r (Aug 24, 2009)

I am having a heck of a time finding a 26" bike that fits... do I need to go custom?


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## Lunchbox362 (Jun 27, 2009)

2tallrid3r said:


> I am having a heck of a time finding a 26" bike that fits... do I need to go custom?


What do you mean "fits"? Like, long wise? Because if you mean leg extension while pedaling....


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## IdleHands (Aug 6, 2010)




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## k1creeker (Jul 30, 2005)

May I suggest a large Giant STP with BMX stem and bars to get the bar height you would need?

The large STPs run a bit larger and longer than most DJs and as stated earlier, you really don't need to be concerned with seat to pedal length, just standing reach and bar height.

http://www.giant-bicycles.com/en-us/bikes/model/stp.frameset/7325/44735/

Not to be another Debbie Downer, but a 29" DJ doesn't make a whole lot of sense.

Best of luck with the build.


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## david8613 (May 31, 2005)

niner is working on a dj bike that looks like a niner rip 9 minus the sudpension. niner bikes really know about 29ers, geometry and fit. here is the link...
http://www.bikerumor.com/2010/09/28...e-concept-bike-new-colors-and-other-trickery/

dont worry about 29er rims not being strong enough, check enve carbon rims stupid strong...
http://www.envecomposites.com/

29ers arent for everyone but for a big guy like you its logical...


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## SHIVER ME TIMBERS (Jan 12, 2004)

2tallrid3r said:


> I am having a heck of a time finding a 26" bike that fits... do I need to go custom?


something to think about...

I have seen a 6 foot 3 guy riding a 20 inch bmx bike on the jumps absolutely killing it...you should fit a 26 inch dirt jumping bike or slopestyle bike....but again it is about preference...


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## newskoolbiker (Oct 17, 2005)

There's a difference between an AM hardtail and a DJ hardtail. There are several AM 29er hardtails, such as the Banshee Paradox, available, and they can certainly strong enoungh to be jumped. DJ 29ers just don't exist. Even that Niner that was mentioned is an AM hardtail. AM hardtails having a little different geometry. While a 26" DJ is more readily available, cheaper, and will come in your size (Jeff Lenosky is like 6'4" or something, pro trials & street rider, and basically designed the Giant STP); if you're good and comfy on the big wheels then get an AM 29er. If have a whole lotta cash to burn, you can get those Enve rims, or you can save a ton and get just as strong Sun MTX 33 29er rims. As for a fork, make sure you get something that can handle the abuse; such as a Manitou Tower Expert with an X-Firm spring and 20mm through axle. So there you go...a tough as hell 29er.


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## kenbentit (Jan 2, 2003)

Canfield's the only one I can think of...


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## NorKal (Jan 13, 2005)

Whatever you do I hope you come back here and post a ride report :thumbsup:


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## False (Feb 18, 2011)

I don't really know what you mean by "can't find a 26" that fits." I'm 6'2" and jump an NS Suburban; hardly one of the longer DJ frames. Apart from strength issues a 29er DJ is never going to have really good jump geo and, IMO, will probably always feel awkward in the air.


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## lelebebbel (Jan 31, 2005)

On a DJ bike you want short chainstays, low frame, small wheels that don't get in the way.
The main advantage of 29er wheels is that they roll better over obstacles, which is of absolutely no concern when dirtjumping... 
As for wheel strength, I'm not going to go into a debate about how strong 29er wheels are, but lets agree that they are definitely not STRONGER than a 26" wheel when built out of the same sort of parts. You'll be landing sideways, casing jumps, crashing. You want the strongest wheels possible. 
In other words, I can't really see any advantage to a 29er DJ bike, but plenty of disadvantages.

Average sized people dirt jump on 20" BMX bikes and 24" mountainbikes, so frame geometry should not be a problem for you with a 26" bike. I'm 6'1" and ride a medium frame with a 23" (584mm) top tubeHeck, DJ frames are built so low that they make 26" wheels look huge...
All you need is taller bars (quite a few models out there) and maybe a longer top tube, 24" (600mm+) or so. Again, quite a few frames to chose from out there.
Don't go too long though, just enough so your knees don't get too close to the bars when pedaling (standing up, of course)

Oh and don't get a 150mm fork for DJ. 80-120mm is plenty, more than that and it'll soak up too much energy when launching off the ground. Also, you don't really need huge tires if the jumps are smooth.


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## joelalamo45 (Aug 3, 2006)

6'6" isn't that tall for a 26" bike... there are several bmx pros in the 6'4"-6'6" range that roll 20's... maybe look into an Atomlab Trailking with the 23"tt and some 3" riser bars. 29'ers for dj's? Not so much IMO.


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## Twisted1 (Aug 24, 2010)

Your son is pretty awesome! How old is he?


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## dirtyknobbies (Apr 19, 2011)

here is my take. 29'ers are just awkard ( have ridden a spec epic 29'er, SE Big Ripper, voodoo rigid 29'er, SC tallboy, Niner WFO). For the record, the Voodoo and SE was the worst of them all, with the WFO right behind them, and the SC Tallboy was actually very nice riding.

In order to make lager wheels work the geometry has to be quite tweaked. This is fine and and a beneficial thing when talking XC geometries. Add the 'fling-ability' now it get's tricky. Once that geometry get's more slack the bikes feel more awkward. The more technical, more high speed cornering the worse these bikes begin to feel. The WFO made me really appreciate and love with a whole new respect my 26" AM bike. Just before the WFO I spent 5 hours on an Ibis Mojo HD which really made the WFO feel like a clumsy incapable bike on the same terrain. Like riding an 18 wheeler I guess...Rubber Ducky!!! 

The ones that I see truly ripping 29'ers in a non XC way are guys that just rip period like Wade Simmons, the dude test riding the Intense DH proto... the guy in the Canfield video. They can just rip and will rip anything with two wheels. Hell even Travis P could probably rip a 29'er on some dirt jumps...they just have natural mad skill.

Not sure what my point is, have had a few beers and can only say I've seen tall dudes above the 6'4" shred 20" and 26" bikes in dirt jumps. So maybe my point is 29'ers are a marketing scheme that is selling right now and not really what is the practical bike for the riding discipline you are seeking. This would be a great question for 'Chopper' in Bike Magazine...seek his knowledge


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## m-dub (Apr 22, 2005)

I have taken my Canfield to the local DJ spot and it works. Its never going to be a DJ bike but its a blast and super stable in the air. My biggest issue is the rear tire buzzing my arse ( and Im 6'2")I buzz my butt when I tuck on my 26" DJ bike but its rare. If your all about straight airs, they work fine and are pretty confidence inspiring. Its just cool that your spending time with your kid no matter what size your wheels are.

Ps. The Canfield has a really low stand over for its length. The problem with going with a shorter frame is tow over lap ( I had issues with that on another frame and it sucks mid air to hear your toe hit the front tire.) Tapered HT is nice also. I wouldn't go over 120 for a jump HT. The more travel makes the geo wacky when hitting rhythm sections and you loose pop ( look at most Dj bikes 80 to 100 is the norm for good reason) If you go custom, chromolly, single speed, 69 HA with a 100 fork would be pretty dialed.

That being said, I still rock a 26er at the jumps/street. Parts are cheaper, tough and so much easier to whip around.


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## chauzie (Mar 8, 2010)

and if you do go custom and go chromoly, just make sure the frame builder knows what he's doing. While chromoly is stiff but it's also hard to weld, and that's where the failures are gonna be.


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## DSFA (Oct 22, 2007)

As mentioned there are tons of tall BMX riders on 20"ers. I'll put a vote out for a long Black Market Mob frame and as also mentioned don't run more than about a 100mm fork for DJ.


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## m-dub (Apr 22, 2005)

chauzie said:


> and if you do go custom and go chromoly, just make sure the frame builder knows what he's doing. While chromoly is stiff but it's also hard to weld, and that's where the failures are gonna be.


Chromoly is usually chosen for its "give" as in a bit of flex (also depends on the wall thickness and series used) As far as welding, in my 10 years as a welder I found nothing unusually hard about the process, its actually a bit easier than other metals? But yes, make sure the builder knows you want it DJ tough and not XC light


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## frorider (Apr 2, 2005)

hucknroll had that size L rocky mountain flow on sale for $699 last i checked. the TT on that bike is long, and the bars have plenty of width and rise...that's just one example of a DJ bike that would fit you.

don't get me wrong, i really dig my canfield yelli screamy...it explodes most of the myths of how 29ers handle...for xc/am riding it rocks..but there is no point that i can see to trying to build a 29er DJ bike.


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## sonic reducer (Apr 12, 2010)

I'm not sure because I've never ridden a 29er on anything but a singletrack, but you may find one harder to pump on some tighter woops and doubles than the smaller wheels. I have noticed a 20" pumps into some stuff a lot easier than 26 so I would imagine the same applies to 29.


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## m-dub (Apr 22, 2005)

sonic reducer said:


> I'm not sure because I've never ridden a 29er on anything but a singletrack, but you may find one harder to pump on some tighter woops and doubles than the smaller wheels. I have noticed a 20" pumps into some stuff a lot easier than 26 so I would imagine the same applies to 29.


I have jumped on my pump track a few times with big wheels and it fits fine. Its a bit slower than a 26" but still fun.:thumbsup:


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## Transition Bikes!!! (Apr 19, 2011)

It will work but its not preferable


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## sriracha (Jun 23, 2004)

i've got a surly karate monkey, 4130 steel. the thing feels like a 26" bike when riding and jumping. they manipulated the seat tube, to achieve extra short chain stays for a 29er.

i laced up some halo rims for the wheel set. they are light and really strong.

i don't go huge on the bike, but i definitely hit jibs on the trail, and it feels quite natural and fun.


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## Axe (Jan 12, 2004)

Why?


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## Pau11y (Oct 15, 2004)

Besides fit, what possible benefit could someone realize w/ a 29" wheel that would supersede a 26" one? Seems every dirt jump track is groomed smooth, minus the airs... Also, wouldn't the larger wheel make things difficult to throw the bike around in the air? Is it a, "because I can"?


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## essenmeinstuff (Sep 4, 2007)

IdleHands said:


>


duno, almost looks like the rider is doing all the right body motions for whips and tables, but the bike refuses to follow...


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## davec113 (May 31, 2006)

Pau11y said:


> Besides fit, what possible benefit could someone realize w/ a 29" wheel that would supersede a 26" one? Seems every dirt jump track is groomed smooth, minus the airs... Also, wouldn't the larger wheel make things difficult to throw the bike around in the air? Is it a, "because I can"?


I agree.

The advantages of 29" wheels will not be noticed on smooth jumps, and the disadvantages will be more noticeable vs. using a 29er for xc.


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## William42 (Oct 29, 2006)

joelalamo45 said:


> 6'6" isn't that tall for a 26" bike... there are several bmx pros in the 6'4"-6'6" range that roll 20's... maybe look into an Atomlab Trailking with the 23"tt and some 3" riser bars. 29'ers for dj's? Not so much IMO.


listen to this guy. he knows what he's talking about. I got a buddy who's 6'6" on a bmx bike, and a 26 should be fine. Small bikes are the way to go for jump bikes, you don't need something that opens you up for pedaling all day, you need something tight and close so its easy to torque and throw around.


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## droptopchevy (Sep 3, 2008)

Twenty Nine Inches from Brian Park on Vimeo.


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## jbsocal (Feb 12, 2011)

I don't know anything about dirt jumping, but when I was researching 29er models, I only came across one that mentioned dirt jumping (and Mountain Cross racing), the Lenz Sport Spankster MTX...

It caught my attention because it was the only model I saw that is available with either 26 or 29 inch wheels.


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