[fitek]

How much difference does a few pounds make on a DJ for park riding?

I got into BMX a couple years ago but it beats up my knees (nearing 40). I also have a P.Slope for dirt jumping which I just tried at the skatepark... way easier on the knees but at 28 pounds and change, and bulkier in general, it's a lot less flickable.

I watch the Godziek brothers video blog and in a recent one Dawid says his new DJ feels almost as good as his BMX. The geo doesn't look hugely different, but his bike is six pounds lighter.

NS Decade: https://nsbikes.com/decade,116,pl.html
P Slope specs: https://www.specialized.com/us/en/p-slope/p/115499

I also happen to have an Octane Zircus One frame I never built up.

NS P Slope Zircus
Wheelbase 1026 1070 1033
Reach 405 423 ?
HT 70 69.5 69.5
ST 70 78.5 72.5
Chainstay 381 389 385
BB -14 -16 -25

 

[slapheadmofo]

Most of the 'less flickable' is due to size more than weight IMO.

 

[93EXCivic]

Most of the 'less flickable' is due to size more than weight IMO.

And geometry.

 

[slapheadmofo]

And geometry.

Yes, that too!

 

[One Pivot]

My bmx race bike was about 28 pounds in the 90's! Thats not light, but I was about 10 years old and still did pretty well on it. All the kids had bikes around that weight though.

Its definitely not the weight.

 

[slapheadmofo]

My bmx race bike was about 28 pounds in the 90's! Thats not light, but I was about 10 years old and still did pretty well on it. All the kids had bikes around that weight though.

Its definitely not the weight.

Yeah - my kid's non-race BMX bikes when he was younger were around 30lbs (better than half his body weight at the time) and it was no issue.

 

[fitek]

I decided to find out myself so I finally built up a cheapy but fairly light DJ. It's about 24 lbs right now and similar geo to my P Slope which is 27 lbs.

My 21.25 TT, needlessly heavy trail BMX is still easier to throw around.

I also rode around two heavier DJs but with different geos-- a long Transition PBJ and a Slater bikes custom build, both about 27-28 lbs.

Geometry wins. The PBJ, which is way longer (40mm extra reach?) and a degree and a half slacker HA than the other bikes, as a DJ for MTBers, works great, but coming from a BMX it feels alien. On straight jumps its fine but riding park stuff I did not like it at all. The Slater weighs the same but felt fantastic-- but it's shorter and has a steeper HA.

Now my skill level is not so great, so the ride is pretty rough and I'm not throwing triple tail whips. Dawid Godziek might need super light wheels to nail a quad whip, I can only get about 270 degrees of one rotation so it doesn't matter But 26" sure is gentler when I case.

The 24 lbs DJ does feel pretty neat and it is still far easier on my knees than the BMX. I built it from a bunch of spare parts so it's a little goofy right now; I'm looking forward to tweaking the setup. One note, it's fairly inexpensive to drop weight by just switching pedals and tires. My crummy pedals are 540g and a $45 raceface Chester is 340g. My tires are 880g each whereas the lightest Maxxis Ikon is sub-500g. That's a weight saving over 2 lbs for $130, a lot cheaper than new wheels!

 

[fitek]

Also, in terms of weight, rotating weight matters more and the further from the center of rotation the weight is, the more it matters. So for wheels, lighter rims matter more than lighter hubs. If you're spinning the bike around in the air, all the bits further from the center of rotation matter more. I tried to order a Tubolito for my rear tire but with shipping from Europe it's not very cost effective.

I also picked up a Chromag Overture seat and really dig it.