# Building a Dirt Jumper Wha Do I need



## FordRaptor (Jul 28, 2014)

Hi ere guys I am building a dirt jumper I am wondering if any body could supply me wit a list of exactly what I need to build it all of the parts need for he build and I would like the rear gear not to be incredibly easy when pedaling. Thanks


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## jaykay (Jul 1, 2010)

A list you say, well, this is the parts list from my latest street/dirt jumper I just built. You can swap out those parts with the equivalent from any other brand - just make sure the sizing matches the frame. You don't need a front brake either, I got that for my street stuff.

Oh, and regarding pedaling, I think you probably wanna work out the gear inches you are comfortable with and choose the equivalent chainring/sprocket that will give you that - a good calculator is here:

BikeCalc.com - Bicycle Gear Inches Chart

The list:

Dartmoor Two6Player Frame - 2100g
Spank 777 Bars - 318g
Primo Boy Grips - 15g
Twenty6 F1.2 Stem - 118g
Chris King Headset - 230g
Fox 34 831 Forks - 1930g
Chris King Hubs - 164g + 411g
Titanium Spokes - 270g
Dartmoor Raider Rims - 1100g
DT Swiss Rim Tape - 20g
Michelin C4 AirComp Latex Tubes - 260g
Continental Race King Tires -1100g
Formula R1 Disc Brakes - 534g
Raceface Bottom Bracket - 92g
Raceface Next SL Cranks - 400g
Raceface Next SL Chainring 28Tooth - 25g
Chris King 12 Tooth Sprocket (calculated with hub weight)
KMC X9 Super Light Chain - 242g
Twenty6 Predator Pedals - 340g
Twenty6 Seat Clamp - 18g
Nukeproof Warhead V2 Seatpost - 235g
Octane One Rocker Saddle - 295g


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## FordRaptor (Jul 28, 2014)

Thank You very much


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## FordRaptor (Jul 28, 2014)

How do I use the chart or what gearing would you suggest


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## jaykay (Jul 1, 2010)

FordRaptor said:


> How do I use the chart or what gearing would you suggest


It's pretty easy really. Just choose your rim size - so for a dirt jumper you'll want 26 inch MTB. Then you need to choose your tire size, in my case I am using 2.2, and then you need to work out what you would want your minimum chainring/cog and maximum chainring/cog sizes to be.

The important thing here is that you need to know what gear inch you are aiming for. What is a bike you ride that has the right amount of resistance to your pedaling? Punch in the chainring/cog/rim size/tire size data and then you'll get your gear inches. You just need to aim for that number with the new bike then.

For example, all my bikes are between 60 and 68 gear inches, that's what works for me for my style of riding, but it may not work for you. They all have different rim sizes/tire sizes etc. But I always aim for something in the 60s low or high depending on the riding


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## cglasford (Sep 26, 2011)

60-68? dang hulk legs! 

For a dj style bike most people run 54-56 gear inch and that is what most bikes are spec'd to. 

you can use that calculator or you can just take your chain ring/cog x wheel size, They say the sweet spot is 55....

I run a 25x12 on my BLT and it works great for me.. I ride park and DJ.... other common sizing is 28x13


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## FordRaptor (Jul 28, 2014)

I am looking at biyung this chainring but how many teeth should I get 30t 32t 34t or 36t

Blackspire Mono Veloce Narrow Wide Chainring | Chain Reaction Cycles


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## cglasford (Sep 26, 2011)

what frame do you have? what cranks do you have ? what is the rear cog going to be? my frame wont fit anything larger than a 28t, make sure you look at that before you buy components


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## jaykay (Jul 1, 2010)

Depends on the cog on the back. Like cglasford said, he's running 25/12. I'm running 28/12 which is harder to push depending on your legs. 

I wouldn't recommend anything over 30. 26, 28, or 30 are fine, but you really need to decide on the rear cog at the same time.


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## FordRaptor (Jul 28, 2014)

how can I tell if it will be hard or easy to pedal for both the front and back


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## jaykay (Jul 1, 2010)

Easier pedal is 56 gear inches, you prolly don't want to go too much under that. What size chainring can the frame take up front? So put in the size chainring you'd like, and the cog up back into the calculator and you'll work it out


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## FordRaptor (Jul 28, 2014)

This is what I have right now

Nukeproof Solum Dirt Jump Frame 2013 
Octane One 3-PCS Pro Crankset 2013 
Nukeproof Warhead 44IETS Headset 
RockShox XC 30 TK Coil Forks - 9mmQR 2014 
Shimano XT Disc Hub Front 32H
Halo Spin Doctor Disc Rear Hub 32H
Ragley Stubbing Evo Stem 
Ragley Wiser Alloy Riser Bars

And I want to run a DMR Single Cassette Sprocket | Chain Reaction Cycles

and a Animal Bikes Sprocky Balboa Sprocket | Chain Reaction Cycles

and do I also need a chainring or no because on other forums people just said I need a front sprocket and rear sprocket


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## jaykay (Jul 1, 2010)

Front sprocket = chainring. Rear sprocket = cog. Amongst other names for both, depending on where you are in the world.


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## FordRaptor (Jul 28, 2014)

how can I find out what size spokes I need


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## jaykay (Jul 1, 2010)

You don't really need to know that detail unless you are personally building your own wheels. I wouldn't recommend that unless you really know what you are doing.

Just drop the hubs into a shop that has the rims you want and choose the spokes there, they'll tell you what they have available or not. For example, I use Hobson Cycles for all my wheel builds: Wheel Builds : Hobson Cycles | Bike Shop Liverpool | Repairs | MTB | BMX | Marin | GT | Saracen | Claud Butler


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## cglasford (Sep 26, 2011)

Yeah wheel building isn't for the faint of heart!

So I would get the 28t sprocket/chain ring you have there Animal Bikes Sprocky Balboa Sprocket | Chain Reaction Cycles

and get either the 12 or 13 cog that you showed here: DMR Single Cassette Sprocket | Chain Reaction Cycles

Depending on what you like for ease of pedaling... I would run the 28x13 personally but Jaykay likes the 28x12... you will get use to what ever you choose rather quickly...

good luck


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