Bike Check: Stout Sigma 13.6

Jul 21, 2012 at 17:40
by Dialed Suburban  

Bike check: Stout Sigma 13.6

My short trials bike
A little back story:

First things first. The frame- Stout Sigma 13.6. Haven’t heard of it? It's a custom frame welded up my Matt Boeckman from Stout bikes (you can find him as Mattty on pinkbike). It was funded by an $800 grant from my school and features the shortest chain stays ever (13.6in slammed) on a 26 in bike. My grant proposal was as follows:

I would like to design and build a prototype Dj/MTBMX frame from the ground up. This would involve redesigning/finding workarounds for problems I believe I can remedy, and finding and purchasing materials to bringing these designs to life. I have plans to increase stiffness, strength and maneuverability of the bike through innovative geometry and metal work. My main goal is to modify the geometry and design to allow for difficult maneuvers to be easier and feel more like they are being preformed on a smaller bike. I plan to devise a method to shorten the chain-stays as short as possible to allow the bike to be nimble and quick and increase the strength in the head-tube area. I also have plans to allow for more tire room in the chain stay-bb junction area. My plans also consist of many small details that will further the strength, durability and practicality of the bike. As the MTBMX/DJ/26in BMX industry is relatively small, radical innovation in frame design is rare. I believe that with my designs I can further the sport by improving on the design of the bike frame. The finished product will be an ultra strong, super durable and nimble bike frame. I have owned more than three bike frames for the same purpose and they have all been lacking in some way or another.

So that was back in March. 2 months later and boom:


I thoroughly enjoy riding Mtb Street and I experience a definite sense of satisfaction when landing a trick or long line. I find this sensation highly addictive and strive to create a frame that is more purpose built and can make street riding even more fun. Not to say that other frames are inadequate, or don't do an excellent job, but I felt the need to push the boundaries and actually make something different. There aren’t a lot of MTB frames that feature sub 14in stays, with a +15 (or more) bb, clearance for an 831 sus fork and have full toe clearance, a low stand over and feature a more than 71* HA. This frame would have to be street. I wanted to design a frame with the tightest geometry physically allowed and still keep a 26-inch wheel.

So the build was going to happen. I finalized the geo and sent it off to Matt so he could use his amazing set of skills to bring it to life.

Geometry is as follows:
HA: 71.75* (at 450 axel to crown)
SA: 75*
ST: length- 230mm
ST: inner diameter-27.2mm
ST: offset- 15mm from the bb
TT: length-22in
TT: angle-27.5
Head-tube length: 110mm
Chain-stay length: 345mm BB height: 360mm
BB width: 83mm extra thick scalloped Spanish bb
Finish: Matte Dark Purple

To elaborate on that a bit: the frame features an 83mm scalloped bb so that the tire can physically enter the bb shell. Ever seen this on a street bike before?

In conjunction (haha get it?) with that, “s” bent chain stays for chain stay clearance, and bent seat stays, which drop into the chain stay. A couple reasons for that:

First: it makes up for some loss of strength and stiffness because of the lack of the chain stay brace.
Second: it makes the bike more vertically strong and laterally stiff.
Third: it’s unique and looks sweet

In addition, an oversized head tube gusset modeled after the one features on deity’ lineup. The main purpose of which was to provide ample clearance for the big knobs on an 831.

A month or so later and photos began to trickle in…

A 83mm scalloped spanish bb!
Matt from stout bikes beautiful metal work. 83mm spanish bb with scallop to allow for 350mm 13.8in chainstays. Absolutely nutz.



Spec list:
Frame: Dark Purple Stout Sigma 13.6
Fork: 2010 Fox 831 (non kashmia) at 100mm
Seat/seatpost: Eclat Complex Combo in black
Wheelset: Atomlab superlight wheel set with titanium spokes.
Crank Arms: Deity vendetta 3 in black 170mm
Spindle: Deity 6in ti
Sprocket: Grape Profile 25t elite spline drive
Bb: Polished profile Spanish bb with custom wide bb spacer for the bb
Chain: Odyssey bluebird
Pedals: Animal Ruben Graphite PC pedals in purple
Valve caps: Deity crown in purple
Seat clamp: Integrated
Bars: Deity topsoil in black
Brake: 2010 Shimano Xt with a 160mm Avid Cleansweep G3
Stem: Thomson x4 elite in black
Grips: Odi Longnecks super soft (flangeless) in black
Headset: Odyssey zero stack integrated in black
Front Tire: Maxxis DTH 2.15 Kevlar
Rear tire: 2.1 KHE Mac 2 Park
Front Tube: Maxxis Ultra light Schrader valve.
Rear tube: whatever shop bontrager tube

Warning: this is all completely biased and most likely hype. Did I expect this frame to make me a better rider? No. Did it increase my performance? Yes. Could it all be hype? Possibly.

In terms of components, my goal was to build a light and strong versatile bike that I can keep without flaking out on parts wise. I want parts that are durable, reliable and easy to maintain. I figured there are certain places where you should not try to save weight, and for me those places are almost always: bars, tires, grips, and frame. With this build and some help from my school, and Matt from stout, my goal was fully achieved. The bike is perfect in my eyes, and at 22.56 pounds it is plenty light with a brake and suspension.


First of all -quality. The frame quality is excellent. The welds are extremely clean, and the metal work is all crisp and symmetrical. The drop stays are dead sexy and both feature the exact same smooth curve down into the chain-stays. The flattened ends of the chain-stays are dimple free. The scallop is smooth all around, and there is zero warping of any of the metal plates. The bb shell snugly fitted my Spanish bearings and the head-tube tolerances are spot on with an almost press in effect with my integrated headset. I will admit, the paint job is not as clean as my deity. But for any of you who do not know, the deity has one of the nicest paint jobs out of all production frames, with a dead even coat and smooth as glass Finnish. The paint on the sigma is more homey, it's very similar to the matte finish I had on my red pincher; slightly inconsistent spray, but only discernible from about 3 Inches away. Other than that, the custom decals are nice and clean and look sweet on the frame. I absolutely love the dark royal purple and it looks insane in daylight. The matte finish does show a lot of show scuffs though, but nothing a Mr clean magic eraser couldn't handle. For a one off custom frame, the quality has exceeded my expectations.

UPDATE: I've had the frame for around 6 months now and its holding up beautifully. There are some little nicks and scratches around, but nothing I can complain about. The headtube is has not ovalized or stretched at all, and the bb area is sound and surprisingly clean. THe dropouts have held up super well, no pinching, bending, paint flaking, and the paint hasnt faded or discolored in any way whatsoever.

The ride. Well, in summary the ride is insanely good. Its really like nothing I have ever ridden before. A coworker of mine, formerly a pretty big bmxer took it for a ride and loved it too. Jokingly attempting a 180 after 5 years off the bike, he was very impressed to see how well it spun. The bike pops of the back like no other. I just recently got my 180s pretty dialed, decently high, quick and doable at nice speeds. In order to get my 180s faster, I normally ride up my driveway at a quick speed and then get the spin down, land, and the upward slope gets my fakie under control. In a very similar practice session (the day after receiving the frame) when I went to spin, I ended up over rotating an extra 90*. Just a few Runs later and I could 3 tap. All that in like 30mins. My spinning also improved at a local bank where I normally ride (not a money bank, a banked wall). I used to hit the bank at really mellow angles to compensate for my under rotating alleyoops. I would go up the bank at like 45* and come down at 90. I know that's not a full alleyoop. Well now, I can hit the bank with the same speed, pop up more and spin faster. Effects? Full beautiful, smooth alleyoops. Same thing on a wedge. Tried and tested compared to my sweeper. Nothing can come close.

Reasons for this are pretty clear. The rear end is nearly the same as the majority of BMX frames on the market. With nearly slammed 13.7 in stays and a short seat tube the back end is extremely maneuverable. That coupled with a high bb, and a lightweight rear wheel, altogether allows the back to lift up extremely high with minimal effort.

The frame also improves my hop height. And not just by a few inches. I'm talking 10+ inches on average. I mainly attribute this to the extremely low seat-tube. I can suck the bike up higher, not unlike a trials rider. The bb height helps me to pop off the rear end and level out in the air, while the short chain-stays keep the rear wheel close to help pick up quicker.

Manuals are super easy now as well. I used to have to kind of pop up and stay way back to keep the bike up, but now, I can do them "bmx style". By that, I mean I can basically just lean back and get low and manual with the front wheel about 2/3 as high as usual. Its nice to be able to do that, especially as a rather small person at 5'8 and like 130 lbs.

All in all, I can’t even compare this frame to anything else I have ever ridden. It’s like nothing I’ve ever experienced. And I’m not over hyping it, I swear. It’s ridiculously agile, quick and low. User effort for nearly every maneuver (except sitting) is DRAMATICALLY reduced. It’s at a level where I can go at the same line for longer, with less fatigue and enjoy myself more. It comes up, and picks up so easily I have difficulty finding an analogy. I’m not trying to stress the reduced user effort aspect of the bike, but it deserves recognizing. Its just plain fun to ride; you can mess around on it like you can on a BMX bike.

UPDATE: In the last 6 months i've gotten pretty good in my eyes, the best ive ever been for sure. Ive been focusing a lot on really placing the wheels and making my riding super clean. I like to do longer lines, and try to always have a plan. I've had a lot of fun with my increased ability to bunny-hop higher. The front wheel maneuverability is really excellent, as i've started doing a lot of nose bonks and foot jams. I have since gotten flat 3s and experimented with alot of different tricks such as oppo alleyoops, G-Turns, tail taps (like trailsy stuff) and other fun things. The bike feels really maneuverable and as ive grown (im about 5'9" it hasn't felt too small or cramped in any way).

The fox 831 is an excellent choice in fork for this particular build. It is extremely smooth (although not important for street) and for the price I got it for, it is actually much more preferable to rigid. The bike seems to have more energy, and the user effort (not to put to much emphasis on this aspect) is reduced for must hops, spins and definitely manuals. As I have been getting better I’ve been starting to realize why people recommend a lowered 36 over the 831. The RLC, although not needed, is cool, but I would rather have high-speed compression adjust (RC2 for fox) to control high-speed compression. The fork valving doesn’t seem as progressive as it could be and it seems to not use full travel. When doing front wheel involved tricks such as foot jams and variations, nose bonks etc, there is a small amount of detected flex. The flex is not so much bad, but is kind of uncomfortable especially when doing say, a foot-jam on a bank and pushing forward and hopping to get back in. The arch is also kind of small for foot jams, but that’s probably me just being really picky. In the future, if the opportunity ever comes, I will opt to trade the 831 for a 36 as I feel that the durability (although not necessary) is much better, and the stiffness and pimp factor are sweet. With a setup as light as I consider mine to be, the extra pound or so in the front end wont do much. On this frame on particular i would like to spend a bit of time on a rigid fork. I believe it would be an interesting experience especially considering how similar the geometry is to a BMX bike. I borrowed a friends for about 2 hours and it was okay, but the bike did not feel as lively or poppy.

UPDATE: THe fork has been serviced relatively recently and it is feeling smooth as ever. I find myself running it slightly stiffer and with more low speed compression each time I mess around with it, and i am thoroughly enjoying its abilities as a fork. I have not lowered it to 80 (which i originally planned to). I feel like it is perfect where it is, and that if it were any lower, I would have to run it too stiff for my liking, and i like a relatively supple fork (as far as street riders go).

The Atomlab Suprelight wheelset with titanium spokes (which i believe i am a pioneer for in the street world) has been quite excellent. The hubs are cleanly designed and spin well, and the engagement in the rear is super solid and not too loud. I much prefer these hubs over the profiles on my rigid setup. The rims are also awesome, a bit narrow at that, but when kept at proper tension they will stay true at anything i can throw at them (limited to big bails and 3 attempts). The spokes however, are a bit flexy and have tended to spin while I true/tension (an odd thing) but they are frickin rainbow and save weight so I cant bitch about that. Recently, well a couple weeks ago I have started to have problems with the rear wheel. It tends to come out of true rather easily and its usually one spoke that just gets looser and looser and throws the wheel off. To remedy this I just true it regularly at the shop and it’s been holding up just fine. In the upcoming weeks I plan to replace them with some classic steel DT champion 2.0-1.8 in black, as from what I have read, they cope with spins and large impacts much better than ti spokes.

EDIT: I tacoed my rear wheel. I replaced the rims with some graphite dartmoor raiders, which have proved to be tons stiffer, stronger, and better looking with only a mild weight penalty.

UPDATE: Ive been on the new rims for a while now and i really, really love them. They feel so much stiffer and when landing back wheel first are very confidence inspiring. The wider tire profile has reduced the amount or pinchflats i get (it could be luck, but i have only gotten one). The finish has held up superbly well and they stay true for ever.

Super amazing. I have the ti spindle and while installing them with the giant steel install tool, I had to put a 38 inch breaker bar at the end of my wrench because the tolerances were so tight. I was surprised to find that the spindle was plenty long to work with my 83mm bb. They look amazing, are light, stiff, and I really don't want to have to take them off. I recently ordered new bolts for them after they were damaged in the installation process. I’m assuming that was because of my extreme methods, but hey, as long as they stay on.

I wanted a sprocket that was spline drive, purple, sold by QBP and came in 25t. Well what a perfect find. The profile elite spline drive is definitely an excellent sprocket. The steel splines hold the spindle tight and give the drivetrain a nice solid feel. This is the second one I have owned and it is just as good as I remember. It looks awesome too- the purple is perfect with the frame and the smooth gloss finish glimmers in the sun. The teeth grab my 1/8 chain well and the weight isn't bad either.

The bar setup feels amazing. The topsoil feel right at home with the frame and the curves and angle allow for an aggressive, confident feel. I get a lot of turning leverage, and they feel great at full length. The dual finish ano is also sweet with the matte and gloss that contrast each other in the light. The bars are nice and stiff and being only 310g, I cant really complain in the weight area. Only real draw back is that they are not very relaxed, which sometimes tires my arms (not much back-sweep). In the future I would want to try out something like an NS roof or even a district bar. I like the swoopy curves of those and could definitely see a high rise bar complementing the frame geo.

UPDATE: Im definitely going to go for that higher bar. I just want something a bit more comfortable, with more sweep and height. The deity bars are great, but with the bb as high as it is, the distance between your feet and the bars can feel a bit short at times.

Its a Thomson elite 4x- probably one of the nicest stems available. Extremely stiff, light, and strong. Very durable finish and I love how clean the CNC work is. The 3mm bolts have yet to be a problem, and only once has it slipped on the steerer. It holds my bars onto the bike; looks sweet, and doesn’t brake the scales.

Shimano Xt 2010 with 160mm g3 rotor. Strong, comfortable lever, reliable, easy to bleed (or so i have heard) and had lots of pad space so rotor rub is a thing of the past. Extremely strong for abubacas and fufanus, although I sometimes find it not as grabby as I would like it to be. That could be the pads, but I’m definitely going to try some organic koolstops next.

UPDATE: Recently its been acting up a bit. It could be the colder weather, but its not feeling very smooth or grabby. i know those are kind of contradictory but bare with me. I like my brake lever to have little travel with a stiff feel and grabby yet smooth modulation (haha still kind of oxymoronic). Whatever. I want it to be better than it is, and i think i might get an XTR brake in the spring. I've been doing alot of weird taps and stall things, and i dont want to kill my index finger by holding the brake so tight.

I've wanted to try these grips for the longest time. I used to ride animal edwins but wore through those super quickly. Then I tried some deity enkois and those were pretty good to me. They were nice, but once a drop of sweat got on them they immediately lost a lot of grip. These ODI longneck super softs are insane. They would be grippy under water- swear to god. Even during these long rides in the summer heat and with greasy hands, they never slip or get that slippery feeling. They look nice and clean, don’t leave residue on my hands and preform great. 10/10 for sure. In regards to durability, I cannot say- only time will tell.

UPDATE: I dont even know how grips could possibly last this long! mabey its my supple hands, or recent glove wearing riding, but they just dont wear. I swear they look brand new, apart from some gouges and scuffs from falls. Great grips.

I saw these pedals, and got them just on an impulse buy. On sale for $18? How can you argue with that? Well, they aren’t just cheap... In addition, they are excellent pedals. I would go as far as to say, that they are the best plastic pedals I have ever used. In the past I have owned odyssey twisteds, Fantastic plastics, premium slim Pcs and some welgo whatevers. These are by far the grippiest and most comfortable of all. To begin with, they have a deep concave and a wide platform. They really cup your foot and the square pins dig into my 510s like sharp metal pins. They are also extremely light at 360g per pair, and the subtle pastel purple goes with my color scheme.

UPDATE: im really easy on pedals and these show hardly any wear. Some of the knurled texture has gone away but all of the grippy square pins have stayed intact. THey dont sheer off like they did on my premium PCs. I have since started wearing vans to ride, and that could change some of the wear properties, but all is well in the pedal department.

Front tire:
DTH are amazing. Probably one of the better tires I have used. It’s great as a front because it has some tread for decent grip, and is pretty soft as well. My favorite thing about DTH is definitely the puncture resistance. The puncture resistance factor is not really advertised, but I find it to do an excellent job. I have ridden on DTH tires back since the pinscher days (last year) and not once (not even once!) have I gotten any type of puncture or pinch flats. It’s amazing that I still have my ultra light tube in there. And I certainly can’t forget the weight. At 567g (confirmed) these things are light. Only drawback is the maxxis logo size. It’s gigantic- huge. I'm okay with it, but after seeing the nice understated logos on the MAC 2, the DTH looks kind of silly.

Rear tire:
I see the hype. I understand now. This is a sweet-ass tire. I originally purchased it so I could have even more tire clearance, but found that this tire is better for much more than that. The rubber compound used is extremely different from a DTH (or so it seems). Initially, I found that the tire was a bit slippery and didn't grip well, but after about 5-6 miles, this thing has really come to life. It actually makes me want to go brakeless so I have more reasons to do brakeless whip skids. The tire skid is so smooth and there is zero chatter. Its kind of more a "slide when you want to grip when you dont" duro.

UPDATE: Um... it kinda split on me. I dont think that it is a problem, but it looks like the casing just kinda pulled apart. I'll keep my eye on the "rip". I cant see the tube, but there are some fraying exposed threads and it looks kinda sketchy.
Must Read This Week


  • + 8
 Trying to snag some more views from reddit?
  • + 3
 Yeah. I want to get some more publicity. I'd like to get a well known rider on it to kind of validate the effectiveness of the design. Mainly to justify a V2 (more production friendly design) as a senior project.
  • + 2
 Sweet write up man! Glad to hear the bike is what you wanted! It makes me want to build up another dirtjumper... If you spruce up the write up a little bit more I wouldn't be surprised if you made the home page!
  • + 2
 that'd be awesome. I definitely think this frame deserves some more attention, even if its just some good publicity for stout.
  • + 1
 Haha, its on homepage under "user generated". dope.
  • + 1
 Nice check bro, as usual. I don't suppose the frame would be the first place you'd notice flex with ti spokes in the back, but are you satisfied that your oversized BB and curved/ovalised stays gets rid of any rear-end flex?
  • + 1
 Well, i havent noticed any flex, so i suppose so.

so yeah, +i definitely agree about your statement about the ti spokes.

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