Bike Check - Matt Jones' Marin Alcatraz

Feb 4, 2018
by Jay French  
Marin Alcatraz Frame designed by Matt over a year ago hasn t gone into full production yet

Returning for a third shot at victory, Matt Jones came prepared for battle with his new Marin Alcatraz. Matt's been instrumental in the build of this bike, everything from the design of the frame to his choice of goodies. Concentrating on weight, this new ride allows Matt to do crazy new things, like send a flip in which he lands on his feet, on a log. Haven't seen that yet? You're missing out.

S2 Bar and S2 stem Bars 730mm wide with a low rise.
S2 Bar and S2 stem. 730mm wide, with a low rise.
ODI sensus grips
ODI Sensus grips

Maxxis DTH usally an Icon on the front but seeing he s riding peoples hand made jumps he wanted slicks not to do damage Tubeless 80psi front and rear Fox 36 831 forks 100mm with factory team orange.
Maxxis DTH tyres - Matt usually runs an Icon on the front, but since he was riding someone's handmade jumps he wanted slicks to avoid doing any damage. Tubeless, 80 psi front and rear. Suspension is handled by a Fox 36 831 fork set to 100mm.

Hydraulic brake with full length hose instead of a gyro 2m long. Approx. 12 bar spins. Grew up racing and using proper brakes no point in putting a BMX gyro on an expensive mountain bike.
Hydraulic brake with full-length hose instead of a gyro, 2m long, or enough for approximately 12 bar spins. Matt grew up racing, and prefers using proper brakes; in his words, there's "no point in putting a BMX gyro on an expensive mountain bike".
This is what that brake hose looks like unravelled.
This is what that brake hose looks like unravelled.

Raceface 6C cranks 165mm long. 1 pound lighter than the cranks Matt used to run. Been running oval chain rings on his enduro bike so trying one out on the dirt bike just for the last minute pedal strokes. Used for consistency across all his bikes no chain growth can run it with a tight chain.
RaceFace SixC cranks, 165mm long. These are one pound lighter than the cranks Matt used to run. He's been running oval chain rings on his enduro bike, so he decided to try one out on his dirt jump bike to have consistency between all his rides.
Gusset Nitro pedals
Gusset Nitro pedals

Gusset S2 seat. grip pads on the seat for bar spins Cut tyre behind the chain ring for crank stoppers.
Gusset S2 seat, with extra grip pads on each side. There's also a cut tire behind the chain ring to slow down the crank rotation when his feet aren't on the pedals.
Halo wheels with super drive rear hub Chaos rims wideboy front hub. Ti bolts weight conscious as light as possible.
Halo wheels with Supadrive rear hub, Chaos rims, Wideboy front hub. There are ti bolts too - Matt is weight conscious, and tried to get his bike as light as possible.



69 Comments

  • 46 1
 Perfect. You don't even need to get arrested to go jail after you ride it, you're already there. #MarinAgainstMTBs
  • 6 6
 Haha. This is clever and funny!
  • 1 0
 I feel like I missed something???
  • 9 0
 Considered the birthplace of mountain biking, Marin county is the place you’re most likely to get arrested for riding on the trails. I think. @stefanfresh:
  • 1 0
 @Triber66: aha... that sucks, big time
  • 2 0
 good one, comment of the day
  • 34 1
 Also how the hell does an oval chainring work on a single speed? Won’t the chain alternate between being too tight and too slack?
  • 6 3
 @employee7 , if your oval is centered properly, the slack and tight spots are not much different to those of round rings on SS setup . Also Absoluteblack rings have great N/W teeth design , that keeps the chain on at all times
  • 2 0
 @samsquamsh: I guess if half the circumference was the same at all points of rotation it would work.
  • 5 0
 yeah...this made my brain hurt
  • 4 0
 @ccolagio: very interesting! You can see a video on the absolute black website that shows cranks spinning and chain tension remaining constant! Mind melting!
  • 3 3
 Erm no not really. It’s a nice theoretical exercise. I have the Absolute Black 34t and I damaged a hanger mid ride on my ht. So had to shorten the chain and go singlespeed. Difference in tension is noticeable. You may possibly find a good middle ground but the oval on SS idea still cries for the answer to the question: WHY?!
  • 1 0
 If you really need your chain length to remain constant you may want an additional fixed pulley to keep the top and lower half of the chain parallel. But if this works for him, why not. Just make sure you just enough slack and the narrow wide chainring will probably keep it on.

I've got an oval chainring too from Blackspire, 32t. But my steel hanger is not replaceable (so probably a bit tougher) and I don't run a clutch rear mech. Not sure if that matters much but I don't think I've damaged anything.
  • 2 1
 @WAKIdesigns: I agree, on a typical SS maybe, but on a jump bike... just WHY!?
  • 1 0
 @SonofBovril: to even out power delivery to the back wheel when pedalling?
  • 1 0
 @WAKIdesigns: Sorry, I misinterpreted your post. No I haven't ridden it single speed (without tensioner). Still, if it works for Matt then great. I'm only going to ask WHY?! once someone mounts one of these to a gearbox bike. That's the far end of my tolerance to "ehrm, yeah, innovation and performance gains".
  • 4 5
 32 teeth are 32 teeth, why would the chain length change if the ring is slightly ovalised?
  • 5 0
 @b45her: If set up properly, the chain doesn't completely wrap the chain ring. Because of the symmetric shape, the chain still covers 16t if it covers half the chain ring. However, on a single speed setup the rear sprocket is often smaller hence the chain covers slightly more than those 16t. So depending on whether it has to cover two high spots of the ring or only one varies to amount of chain it needs. I didn't expect this to matter but according to WAKI it does.

Heck, if this wasn't clear already we really need a graphical interface here in the comment section or just refrain from anything remotely technical. There is only so much I can discuss with words only.

On a related note, in other discussions it seems like the comment section also needs a way to exchange physical violence. I frequently put my head between my laptop and slam it shut to completely experience the vibe going on, but it still isn't quite the same.
  • 1 0
 b@45her - that would be true if rear cog would be as big as the chainring, but since he has 16t back his chain wrap around let’s say 16 abd 17 teeth of a 32t chainring depending on it’s location. Just put a chain on smallest sprocket on a cassette/ derailleur equipped bike and you’ll see the cage moving a little bit back and forth. The effect disappears when on largest sprocket. Difference is little but it exists and you just give yourself a bit of additional pain in the arse when setting up your SS, which I personally hate on bikes with non integrated tugs
  • 1 0
 @vinay: actual lolz
  • 2 0
 @employee7: if the circumference is the same at all points of rotation then it’s not oval :p
  • 1 0
 @TheLongMan: if The Creator exists, he just got a seizure
  • 1 1
 The chain should have the same tension with the oval in a vertical position as it will in its horizontal position.
  • 1 0
 @TheLongMan: You're getting circumference and radius confused. You could have an identical circumference on both an oval and a circle, but the oval will have varying radii at a given point while the circle won't.
  • 1 0
 @WAKIdesigns: He doesn't so he didn't.
  • 1 0
 @bvd453: you talk like a preacher who is as certain that he exists as you are that he doesn’t... makes me think you both look at the problem in a wrong way...
  • 1 0
 @WAKIdesigns: I'm not certain that a creator doesn't exist, but I'm certain there's no evidence one does. That's a major distinction.
  • 1 0
 @bvd453: good. Existential angst is a fantastic thing
  • 24 2
 Oval chainring for more efficient pedal stroke. Cut tire behind chainring for less efficient pedal stroke.
  • 4 0
 Oval on single speed.....?
  • 5 0
 @nojzilla: is it a single speed with an oval? I think more of a 1.5 speed.
  • 3 2
 I don’t know how is it with you guys but I’m waiting for oval SS cogs. And then Oval cassettes...
  • 16 0
 @WAKIdesigns: Still waiting for oval wheels to sort the wheel size debate once and for all.
  • 1 0
 @vinay: yes that would be better than modern short travel bikes squeezing juices out of your local trails, since it would make them more bumpy...
  • 5 0
 Did everyone missed the point that he decided to run this because he is used to it on his other rigs? It sounds to me that he just wants to get the same feeling, maybe it's even only psychological
  • 3 0
 @vinay: 26" horizontally, 29" vertically, 25.7 somewhere in the middle to please everyone.
  • 2 0
 @davidrobinsonphoto: with a 28.99 ratio?
  • 13 0
 "Matt designed the Marin Alcatraz frame over a year ago, but it hasn't gone into production yet.".... you can buy the frame from Marin, its on their website...
  • 2 0
 the article stresses weight savings a couple of times. Where's the weight of the complete bike then? Agreed it has some super light components but some others are relatively heavy. How does that compare e.g. to Rogatkin's bike?
  • 3 2
 How much designing can you really do on a DJ hardtail? He probably went- yeah I've been using this frame for ages - can you make me the exact same thing with a Marin logo on it? Maybe choosing the colour counts as design these days?!!
  • 3 0
 I mean it's still a bike. Subtleties in bb height, stay length, stack height, etc. I agree though, it probably took him a couple hours on his couch and three or four emails with the engineers.
  • 1 0
 How did he get tubeless to work? No one noticed that?

When I ran tubeless on my dirtjumper, my tires would just roll in on bank and spins, leaving me with 15 out of 80 psi... I have learned some tubeless tricks since then, but still, I am dumbfounded...
  • 2 0
 I’m running tubeless on my dirt jumper. Works like a dream, however I have stans wheels so.
  • 3 0
 "No point in putting a BMX gyro on an expensive mountain bike", couldn't agree more!
  • 6 3
 Pointless application of oval chainring.
  • 7 4
 He's brave running Raceface Carbon cranks.
  • 5 2
 Needs a Harry Main respray.
  • 14 2
 Harry Main is a muppet. He goes on about how he's too busy to clean his bikes properly but he finds time to paint his hardtail twice and make it look shit!
  • 1 0
 @gavlaa: I knew that would annoy people. Nothing wrong with being a muppet as long as you're harmless. I'm not that au fait with him to decide either way. Just prefer alien puke fluo green to these graphics.
  • 2 1
 I hope Harry starts doing some MTB comps soon.
  • 3 0
 @cains08: I'm not sure he'll get very far right now.
  • 3 0
 Supadrive
  • 3 2
 I want a dirt jumper really bad, but I’m on a XC team, and I need a new bike. So maybe In a few years.
  • 3 0
 Do it and then race it at a laid back XC race... that's always a good time. Check the pinkbike buy/sell. I've had good luck finding things there and I never can justify buying a new DJ bike since I'll just trash it haha. Considering you are supposedly in Utah I'm sure you could find something for a reasonable price.
  • 2 0
 Yeah I picked up a trek ticket frame for 250 in the classifieds. Do it!
  • 3 1
 Get a bmx if you can't afford a DJ. It's more fun overall and you won't feel bad bashing it about
  • 2 0
 Yeah if you're in Utah just scan KSL, I got a complete DJ for $125 on there!
  • 2 0
 @taquitos: I have, but I’ve got to earn enough money first. But thanks! And I’ve been checking KSL.
  • 2 0
 Looks weird without the big WD40 sticker.
  • 2 0
 Love a straightforward DJ
  • 2 0
 80 psi?! Concrete rubber!!
  • 1 0
 80 psi? i thought running on the low teens with 2.8 tires was the fastest for everything.
  • 1 0
 Frame already sold in Europe. Does anybody have an idea where I still can get one?
  • 2 1
 proper brakes, give me a break
  • 7 0
 Probably doesn't want to spend money on dental surgery, teeth are XTR.
  • 1 0
 That brake hose seems legit
  • 1 0
 Matt's gonna escape on that Alcatraz... Sweet bike.
  • 1 0
 Looks like Polygon Trid / Cozmic DX on Dropout
  • 2 5
 #fakenews

Post a Comment



Copyright © 2000 - 2020. Pinkbike.com. All rights reserved.
dv56 0.018152
Mobile Version of Website