[Closed] Building an octane one Dj bike with a RS Judy

I think the damping send spring rates would likely be bad, having a lockout is super useful too for harder pump tracks.

Thanks 5lab
Maybe the Judy silver at £110 that has the turnkey lockout
https://www.chainreactioncycles.com/rockshox-judy-silver-tk-solo-air-boost-forks/rp-prod196057

I presumed the Judy gold would come with the same lockout

I should image the fork would be fine if you keep the jumping smooth or small.plus as its air you can stiffen it up easily and try different rates.

@trumpton thats what i thought the frame can take upto 130mm fork so the geometry depends on the fork.

looking at the ebay sellers of said judy silver / gold, the gold needs the silly remote bar lever, hence its still on sale, rather than the blue lockout switch at the top of the fork, may go for the cheaper Silver. or an recon 120mm is on offer too

I might be tempted to go for the silver over the gold for the steel stanchions in that application. I use an old 32mm stanchion recon with a 20mm bolt through on my zircus and it is fine for bmx tracks, pumptracks etc.

ordered the judy silver £100, thanks Ianpv

Now £90 with code CLEAR2020, crc are issuing me a credit 🙂

Well done.hope you enjoy your build.

thanks @trumpton

i was until i started looking at cranksets, i forgot the majority start at 30T, so likely need a race face aeffect.

and then integrated headsets gets complicated. my head hurt last night.
tapered steerer
i have in my spares bin a new cane creek10 IS41/8.6 & IS52/40 and a hope crownrace.

this bike needs IS42/ IS52
looing at IS41 versus IS42 they appear very similiar (is41 is cane creek 1 1.8 <> is42 is italian 1 1/8)

on the IS52/40 i'm guessing 40 is the depth (of 4mm), recommended for the bike is either IS52/30 or IS52/39.8

Think i'll just get the recommended £13 brandX integrated headset. and mix match..

confused

Use BMX cranks?

Definitely use BMX cranks on a DJ bike. You can run the correct (small) sprocket and a decent (fatter, stronger) chain. This might prevent you from being fired onto your face when your little MTB chain snaps while you're cranking into a big booter. Ask me how I know.

Just avoid the cheapest-of-the-cheap kind where there's a pinch bolt on the axle.

Something like this would be fine- LINK

Then you want what BMX'ers call a Euro bottom bracket which will fit the regular MTB shell on your frame.

Look for wheels which have a dedicated SS rear hub and you can run a tough little BMX style sprocket which will fit your BMX chain perfectly. I've got NS wheels from Pinkbike classifieds but look for Halo and DMR stuff which is similar.

Definitely use BMX cranks on a DJ bike. You can run the correct (small) sprocket and a decent (fatter, stronger) chain. This might prevent you from being fired onto your face when your little MTB chain snaps while you’re cranking into a big booter. Ask me how I know.

A set of HT2 with a 30T ring would be fine unless you want to go microdrive. You can still put a fat singlespeed chain on either way, the pitch makes as much as no difference.

thanks sharkattack, looks a good set of bmx arms, do the euro/spanish BB last well, as i'll likely get it muddy/wet now and again

I've ordered an octane one SS pro 135x10mm which comes with a 10t sprocket, so maybe too higher a gear with a 30T, hence the thinking behind the aeffect as they do 26t and 28t direct mounts.

was looking at this aeffect race face 24mm spindle fits regular BSA 68/73mm
https://www.bike-discount.de/en/buy/race-face-aeffect-sl-24-34-boost-crank-957153
71 euros, compared to £100+ for the arms on most uk sites

only downside is its 175mm arms, would prefer 170mm and it also states boost, so im thinking the Q factor maybe be too far out. As a bonus can sell on the spider and chainrings it comes with.

You can get a cinch chainring in 24t which would be better suited

yeah i'm now thinking a 28t / 10t rear will be far too high a gear. [2.8]

do you think i can change the 10T sprocket on the rear hub to a 14t on the octane one pro SS rear hub

I've just been to check what's on my bike. It's currently 25/10. When I built it I guessed and went 28/10 and it was useless. Hilariously fast on the move but I could barely get going.

You can probably change the rear sprocket but have you seen how much those little one piece drivers are? I think a replacement for my NS hub is about 80 quid.

I'd just keep the 10 and go 25 max on the front. No idea what MTB cranks that restricts you to.

Thanks for the advise on gearing ratios, I think I.ll hold off the crank purchase till i get the rear hub and frame.
I can see bmx sprockets for the £10-15 mark on tredz so could up the rear
And stick with a 28t, but as you say ignorance I get an octane or ns the part could be expensive.

I’ve got a spare mt800 bb so a raceface aeffect come in
But I like the look of those bmx cranks you posted earlier

I have no idea on bmx chainrings are they all the same fit

I have no idea on bmx chainrings are they all the same fit

Hell no! That would be too easy.

That link I posted earlier is a small BMX shop in Sheffield I'd give them a ring and tell them what you want. They'd make sure you get the correct combo of cranks, bb and sprocket. It saves you from gambling on different mail order places and buying the wrong piece.

Ask for a matching chain as well. They come in 2 different widths and obviously I bought the wrong one first time. I thought it would 'bed in' but it actually snapped a few miles from home.

Next time I’ll stick to building a regular hardtail 😂

You can't change to a different sprocket on the solar pros. If you can get the aeffect and a 24t chainring cheap(ish) go for that combo if not give source or alans BMX a call and they'll be able to put the right combo together for you

i managed to get an octane one SS pro on a german site and its been shipped, amazing they had stock when octane one/distributor couldnt tell me when they would get any in.

its 135x10mm with a 10t, i'll wait till it arrives and see if the sprocket is replaceable, like you say it probably isnt.

once i know that I'll get some wheels built up and i'll have time to decide on crank/bmx chainring etc.

You haven't said what your local trails are yet. Where are you going to ride this thing?

leeds bike park, manchester dirtfactory, and local woods, and to go see the wife/ and her horse in summer. plenty of west yorkshire hills..

a 24T / 10T will be a good option by the sound of it if i cant find a bigger sprocket to fit

I quite like the look of these and could move most parts over from a dailled love/hate but can you not just use bigger rings front and rear , 40-16 (both of which I already have) looks the same gear inch as 25-10

Edit: ohh that's why --Biggest Chainring: Up to 34T

You won't find a bigger sprocket, I bought a pair when wiggle were selling them for £99 a few months back and it's not possible.

Edit* first thing you should do is completely desticker them as they look ridiculous. Solid wheels though

Update, found a saint BB in garage so ordered an aeffect crank £66 from Germany, will sell on the double chainring/ spider and looks like a 26t snaggletooth ,
Judy silver fork arrived a bit basic, but hasn’t a blue crown lockout, unlike the Judy gold with the oneloc crown that needs a £55 lever remote to work it, plastic turnkey rebound feels like it’ll snap as does the maxle lite., 2.3kg but feels sturdy otherwise and £90

Frame and rear hub should be hear in the next few days.
Seen lots of singlespeed cogs in the past few days so will disassemble and see if anything looks like it’ll fit

Got some freebie wheels

Those Judy's are kinda irresistible with another tenner off.
Oops pressed buy

Watching with interest as my Octane One Zircus frame arrived yesterday, intention is to ride it on local pump tracks and my youngest will probably use it as well as me.

Torn between BMX crank or RF Chester crankset which i've seen someone build an Octane with, quick Q, is 27.5/26" mulllet style common on DJ/pump track set ups?

no, just stick with 26" wheels. If anything, 24" is more common than anything bigger - the only larger wheels I ever see is people failing to get normal mountain bikes round the track (too long, tyres too draggy, too much suspension, etc)

The raceface Chester’s will only allow a smallest 28t/30t chainring , so bear that in mind when buying cranks, as the singlespeed hubs 135mm/10mm all come with a 10T, So it may be best to get a single speed conversion kit onto an old rear hub..

I’ve bought a raceface aeffect crank on bike-discount £66 with the intention to sell on the spider and chainrings, and get a blackspire snaggletooth 26T,
it’s 175mm arms though,
Set up a load of eBay saved searchers

So I may go for the bmx arms instead, lots to think about on this build

I've never seen a mullet jump bike and in general bigger wheels are just harder work on track. Plus you'll be stuck for tyres. Lots of smooth, fast DJ style tyres available for 26" wheels. The DMR Moto is an old favourite.

I haven't seen a 24" bike anywhere for years.

Lots of great info here.

I am currently building a DJ/pump track bike up. I know mountain bikes.... I don't know DJ bikes! its a whole new world.

I have a Saracen amplitude frame. Have sorted a headset and manitou forks for it.

next up is a set of wheels. Most seem to be sold out at the moment. But I can get some Halo T2's which should do the job. front's are in stock, rears are in stock with a single speed, or on back order for a freehub. I was set on waiting for the freehub, but after reading the above, should I just get the single speed that is in stock? It comes with a 10t sprocket. which then makes me wonder what size front I would need to run?

I haven’t seen a 24″ bike anywhere for years.

I bet you've seen a Danny Macaskill or Fabio Wibmer video, right?

I've not looked but I bet you can still get plenty of 24" DJ style tyres, even if only from trials shops.

I was set on waiting for the freehub, but after reading the above, should I just get the single speed that is in stock? It comes with a 10t sprocket. which then makes me wonder what size front I would need to run?

Do it! Dedicated single speed wheels are just nice to me than MTB hubs with ugly conversion kits on, maybe I'm a snob but why not have the right tool for the job? Then get BMX tubular cranks with a euro BB and a 24 or 45t sprocket.

I’ve not looked but I bet you can still get plenty of 24″ DJ style tyres, even if only from trials shops.

Well maybe you can, but we've got a bunch of people here building their first pump-track and DJ bikes so why complicate it? It's pretty much 100% 26" wheels out there.

I know one person on a 24" bike and it's some kind of gusseted, gas pipe monstrosity from 2004 that weighs about 40 lbs. He only rides it because everyone hates it.

@sharkattack cool, I appreciate the advice and it makes sense. I kinda thought about the freehub as it would give me more 'options' in future. but the reality is, I wont ever change it.

I also assume you mean a 24 or 25t front sprocket... not a 45 🙂 haha

Yes! Did you see my post above? I went 28/10 first time and had to pull away using a Fred Flinstone technique. Do not buy a 45.

my jump bike (which was a complete) is a 28-12 ratio, on 2.3" dth tyres (which are great), and I'd say the ratio is perfect. So if you're on a 10t rear, you probably want 23/24t front ring. if you're running 32t front, you probably need a 14ish at the back.

I wasn't suggesting that anyone should build up a 24" bike, but DMR and NS still sell brand new 24" dirt jump frames (ns one might be for kids, not sure) - and there's loads of 24" bmxs around. I've never seen a 650b jump bike.

awesome, thanks for the advice guys! And apologies to the OP for the thread hijack!

Now thinking bmx arms I do like the look of those blank generation tsc bmx cranks
I notice they are a 19mm spindle so will
These fit the FSA BB-4000P megaexo 19 cartridge BB
It’s threaded and 19mm

Also will the salt gateway 25t sprocket fit
(It says it includes a 19mm spindle adaptor so presumably does

V7fmp hack away the more info the better I know my mtb but not DJ/BMX standards ;0(

cool cool.

my wheels are ordered! yay.

just need tyres now... something good for pump tracks, dirt jumps and street riding.... an all rounder??

I have DMR Moto Diggers on mine since they were there when I got it and haven't worn out yet. I think I'd get the RT version if I was replacing them now since I'm only really riding it on hardpack

maxxis dth here, I'd get them again based purely on name (which I had always assumed was 'down to huck' - but apparently its 'drop the hammer'. sadface). comes in skinwall, which looks nice on a tidy dj bike

@v7fmp - Interested in your wheel/hub choice, could you share?

I'm lookng at re purposing the wheelset coming off my old Intense 6.6, Mavic rims with Hope Pro 2's - Unsure if I can convert the rear hub to BMX/singlespeed freewheel you see...

@theperfectkiss - went halo T2's. maybe not the most flash wheels, but trying not to spend a fortune. Got them from www.slam69.co.uk who are one of the very few places to have stock.

Unsure if I can convert the rear hub to BMX/singlespeed freewheel you see

You don't have to.

One of these will fit on your existing freehub body,

Amazing, thanks... Just need one of those in Shimano freehub version

and then a Hope Pro 2 conversion kit to 10mm bolt in, just need to find stock now!...

you might want to budget/find chain tugs as well. its possible to set up a rear wheel without them, but much easier if you've got some. not sure if they come with the frame or not

Judy arrived today ... now waiting for a mystery frame to arrive to see what else fits.

yes, you'll want chaintugs. Bit of a pain on the zircus as the sliding drops are so short but I managed to find one in the end. I think I'm only running one on the drive side, can't quite remember!