Ron - done

29 with clearance for 27.5+ seems to be all the rage these days. Fun way to have 2 bikes in one (though IMO the 27.5x3, 29x2, 26x4 bike is the way to go if you really want the Swiss army knife effect!)

This one is an all-arounder with Rohloff capabilities as well as the usual stealth dropper, loads of tire clearance, etc.

Still all fluxy

I can't resist putting curved bridges on these bikes with big tire clearance...

Random photos for Ron

29/27.5+ with Rohloff/SS/geared capabilities, fun times.

Cleaned up and vented for DT welding-in

Fluxy

Like a boss

Front end

Toptube oxide rainbows

2015 Build Kits: Dirtbags rejoice!

Everything good enough to ride like you mean it, but nothing blingy. Monday: Dream Build!

2015 Dirtbag Build: No pedals, no saddle, shipping not included. If you already have some parts you want to use you're not obligated to buy the full kit, as always.

Geared: $2900
Singlespeed: $2700
Full squish: $3900

Frame	Waltworks Custom
Fork	X Fusion Slide or Velvet
Shock	None/hardtail
Headset	Cane Creek 40
Stem	Kalloy Ultralite
Handlebar	Truvativ aluminum flat
Brake levers	FR-5
Shifters	GX
Front derailleur	None
Rear derailleur	GX
Bottom Bracket	w/cranks
Chain	GX
Cassette	GX 10-42
Crankset	GX w/BB and 32t ring
Pedals	None
Cables/housing	Included
Seatpost	Kalloy
Brakes	Avid BB-7
Skewers	Included w/wheels
Wheelset	ZTR Crest/Arch/Flow
RimStrips	Included
Tubes	None
Tires	Maxxis Ignitor folding
Grips/tape	WCS
Saddle	None

What you've all been waiting for... 2015 build kits: Smart Money

Hey, 2015 is... more than half over. And I finally got around to doing a new set of build kits.

Here's this year's "Smart" money kit. Notes: no pedals or saddle, shipping not included. GX cranks may be unappealing to some, but you're better off spending that money elsewhere IMO. Front derailleurs are still dead.


Smart Money 2015:

$3600 geared

$3200 singlespeed

$4600 full squish

Replace that old-school rigid post with a Thomson dropper for an extra $200!

Frame	Waltworks Custom
Fork	Rockshox Reba
Headset	King
Stem	Thomson X4
Handlebar	Easton EC70
Shifters	X1 trigger
Front derailleur	None
Rear derailleur	X1
Bottom Bracket	w/cranks
Chain	X1
Cassette	X1 10-42
Crankset	SRAM GX w/32t ring and BB
Pedals	None
Cables/housing	Included w/shifter
Seatpost	Thomson Elite
Brakes	Shimano XT w/160mm rotors
Skewers	Included
Wheelset	ZTR Crest/Arch/Flow wheelset w/XD driver
RimStrips	Included
Tubes	None, tubeless!
Tires	Bontrager XR team series TLR (I like the XR2 for all-around fun)
Grips/tape	Ritchey WCS

Sunday Quiz!

Which frame is for a 6'10" rider, and which is for a 4'10" one?

Hint: Purple=normal size person.

Joe's Geometry Jamboree

By popular (ok, one person) request!

Executive summary: short and semi-slack racey bike for attacking the twisties in TX.

New bandsaw says, "I am not impressed"

-69.5 HTA and 90mm trail, designed for a Niner carbon rigid fork or 80-100mm travel suspension

-60.5cm ETT, 66.9cm front center, 107.8cm wheelbase. 

-42cm chainstays, plenty of room for a 2.3 and a 34t oval chainring (lotsa runout on those bad boys - I had to have Joe send me the crank and ring to double check clearances)

-295mm BB height. Just a smidge on the low side if you were running suspension but with a rigid fork you can go a hair lower and Joe likes low.

-Curved seat tube for tire clearance. Joe took it easy on me and let me use straight tubes for the rest of the front end. 

-Built for a nice normal 27.2 post and using nice skinny-ish 35mm/28.6mm down and toptubes for a steel-is-real ride with a little give. Joe is not a huge dude either, so fat tubes were never on the radar.

-Paragon rockers for SS fun if needed, plus chainstay length adjustability.

Ken, 148x12, the future, Keanu Reeves

As promised, here's part 1 of my thoughts, musings, ramblings... incoherent gibberish about new axle standards.

I'm not even going into the new 110x15 fork standard right now, we'll concentrate on 148x12.

First, remember: if you are buying a hardtail, a through axle has no actual benefit over a QR unless you weigh 400 pounds or are constantly forgetting to tighten your skewer. Your pathetic excuses for legs won't get any more power to the ground than they did before - the rear end of a hardtail really doesn't flex much, so adding a big fat axle make zero difference in how the bike rides. Of course, I build them all the time, and if/when I get around to building myself a new bike, that's what I'll do. Why? Because time marches on, and it's harder and harder to get nice QR parts - just like it's hard to find a really nice set of v-brakes these days. C'est la vie. Take the red pill. Or maybe the blue one? I can't remember, the sequels have caused me to block all Matrix-related knowledge from my brain to avoid the pain.

142x12 came out about 3 years ago and quickly took the world by storm. Why? It promised a bit stiffer rear ends on FS bikes, compatibility via adapter for most existing hubs as the cassette and disc rotor stayed in exactly the same place, and something new to sell to the bike-buying public. Which I would roundly condemn, except that I'm one of the purveyors of said new stuff.

27.5+? My doing.

As a giant world of diverse wheel/tire and drivetrain options has opened up in the post-29er glasnost, lots of manufacturers realized that cramming 3x29/27.5" tires into frames built around 73mm BB shells and 50mm chainlines (just a quick pause for a definition here: "chainline" here means the distance from the center of the frame to the center of the middle chainring, though these days that mostly means the *only* chainring. Here's Sheldon Brown's definition) would cause some terrible problems fitting everything where it needed to go. The chainstay, tire, and chainring all fight for space on a typical mountain bike frame (FS or hardtail) and if you have to give too much to the tire - you've either gotta lengthen the chainstays or do *something* to move the chainring out of the way. As more and more gears get crammed onto cassettes, the flanges of the hub have also gotten closer together (this has been going on for 20 years, really) which is generally bad, as the spoke tension between driveside/non driveside gets out of whack and the wheel gets less laterally stiff and weaker. Bigger rims (ie 27.5, 29) exaggerate these problems. Something had to give (well, ok, maybe "had" is too strong a word). Something is giving, anyway.

Enter "Boost" (why didn't 142x12 get a cool name?) 148x12 rear ends. The idea here is that you move both the cassette and disc rotor outboard 3mm, and move the flanges out to match. Result, you can move the *chainring* out a bit to make more room for the tire, keep a decent chainline, and end up with a bit stronger rear wheel to boot.

Now, there's another solution out there that I've been doing for over a decade along with a few other weirdos. It's to stick with 135x10 (or now142x12) spacing, but move the *entire* rear end (meaning, the hub/dropouts/stays) about 5-10mm to the driveside (the exact amount depending on application). This gives you a great chainline for single ring bikes and loads of room for short chainstays and big tires. It's also a near-dishless/even tension rear wheel. Great stuff, IMO. Cannondale ripped me off this year with their "AI system" (here's C'dale's explanation of the setup). Stupidmobile (you know, the 29er with 40cm chainstays?) was built this way. So are many bikes I build for customers, because it gives you a ton of benefits and really only has a few drawbacks. You can also do fun stuff like an 83mm low-q-factor fatbike by using various amounts of rear end offset (Felix's runs a 135x10 rear hub offset 10mm).

Whew. Did that all make sense? No? That's what I run into a lot. Many people don't like the idea of asymmetry, so the whole idea is off the table. I think that's a big part of the 148x12 idea - easier to explain, inherently less weird and threatening...but we don't do normal and unthreatening around here!

Ken wanted it *all*. 148x12, lots of tire clearance (in his case 27.5x2.8-3 or so) and short, short chainstays (well, not totally insane - we did 41.5cm). So we went nuts and did an *offset 148x12* setup. In this case, it's just 2mm of offset to get the chainline we wanted, but it still felt weird to take a brand new Anvil dummy axle and chuck it up on the lathe!

So long story short, Ken's bike is weird but should be awesome. Your bike can be awesome too if you think outside the box a bit and let me get creative - it's custom, folks. The world is your oyster.

Or we can just do 148x12, because what the heck, I already paid for the dummy axle, and the writing is on the wall...

Pictures from Minh

Minh says: "shamefully, that's a gold chain to match the kashima". Details and geekery here.

Minh's garage is a bit cleaner than mine.

At least the tires are dirty.

Totally Unbiased Review: Stupidmobile

First off, just to make sure we're clear - the manufacturer of this bicycle made me do something like 10 hours of work, for no pay, just so I could ride it. The company made me pay for all the parts as well as powdercoating the frame and didn't even give me an employee discount. Apparently if I break it, I have to fix it myself.

Bastards.

Sorry about all the shadows. 

So I decided to name it "Stupidmobile". Why? Well, mostly because this bike has the most ridiculously short chainstays you've ever heard of (40 cm, or 394cm if measured horizontally). A 2.1" 29er tire only has 15mm of clearance to the BB shell itself. There's not much way to go a whole lot shorter and for someone who has a 36" inseam, the whole idea of chainstays this short is... well, stupid. Right?

Well, not so fast. My first ride (around the block, in the rain) had me pretty worried - so much so that I pulled out the angle finder to check things over, because it seemed MUCH too twitchy for a bike with a 69 degree head tube angle. After confirming things were right, a little cogitation solved the mystery: I had been riding exclusively on the cargo bike (7' wheelbase!) all winter. Any "normal" single bike was going to feel weird.

Nevertheless, I was still nervous last week when the trails dried out enough to get some real rides in. I set out to find out just how stupid Stupidmobile actually was by riding a number of variations on our local (literally a 10 minute ride from the door) trail system. The Shoreline trail is mostly bench cut singletrack on steep, semi-rocky (limestone) soil. It occasionally wanders up a drainage (the Dry Creek section is a classic) or a mountain (Mt. Van Cott is a fun way to cough up a lung) and it features what might be the most fun section of singletrack in Utah - the Bobsled (yes, it's really berms the whole way, yes, those guys are jerks for riding it when it's muddy). Long story short, it's got most of your types of XC terrain to test frame geometry.

I have to admit that at first, I wasn't riding the bike very well. I was oversteering everything due to the super short wheelbase - the bike steers much quicker than you'd expect from something with a 69 degree head tube angle and coming from an FS bike (my main ride in 2012) with almost an extra 1.5" of wheelbase, it was a bit of a shock. If you leave your butt in the saddle over any kind of rough terrain the tucked-under rear wheel will let you know in a hurry by attempting to eject you. I managed to not crash up the Dry Creek climb and figured I'd take it easy on the Bobsled. Unfortunately, I was with my buddy Paz Ortiz who is not only the only non-douche realtor I know in SLC but also a really badass descender and enduro/SuperD racer. He and I always duke it out on the descents so I ended up riding way faster than I should have.

Man, that rear tire is close to that bottom bracket. 

The results were stunningly awesome. Stupidmobile's short wheelbase let me rip through the berms and the slack front end made things manageable on the rougher and straighter stuff (though to be fair I think a longer bike would be better on the rough/fast/straight sections). I've got experience with this type of geometry and in fact I've been riding similar bikes for years - but I figured there would be diminishing returns under 42cm or so of chainstay length and 42" wheelbase (at least for me). I was wrong. The bike is probably not *faster* on most terrain but it's not slower than a longer bike either and it's super, duper fun for trails where jumping, flying, and general silliness are your goal. Would you be faster in a race? Probably not - the bike is pretty unforgiving of mistakes and a poorly executed bunnyhop that comes up short over a log or rock is going to result in an ass-over-teakettle disaster. I don't even want to imagine how hard it would be to keep things under control after a few hard climbing efforts with your whole body exhausted and your brain on autopilot. It would be bad.

But for rides under 2 hours, or short races, or anything where the goal is fun and not playing chicken with your lactate threshold? Awesome. I love it, I don't regret a thing. I'd recommend it to customers, even, with a few caveats (see the bullet points below).

Awesome stuff:

-Very "intuitive" and hip/lean steering action. If body english is your preferred steering method, this is the kind of bike for you. If you like to jump over/wheelie over/roll up the berm to the side of obstacles, this geometry will help you do it.

-Great climbing traction whether standing or sitting. Man, there's a lot of weight on that rear wheel.

-It's very easy to unweight the front wheel (shocking, I know) for getting up over obstacles whether you're going uphill or down.

-Just plain fun. But then again, it's a mountain bike. Pretty much all mountain bikes are fun unless you're a seriously grouchy individual.

Not much creativity from the Waltworks photography div. on display here.

Not so awesome:

-Mistakes will be punished severely. If you come up short on that jump over the little rocky section your dentist will be getting another mistress and/or boat, probably. Kidding aside, this is a terrible geometry for riding where you'll be trying to go fast when you're not fresh and alert. You need to be on the gas and be paying attention to your lines because the bike won't bail you out of a lot of mistakes that a longer one would.

-Unless your technique is very good or you run a very low bar position, it's hard to keep the front wheel down on some steep climbs. The lack of weight on the front wheel and general high trail number mean that this bike does want to wander on slow technical climbing - those who really enjoy that type of stuff may want an adjustable travel fork or a bit different geometry. It's not unmanageable but it's also far from a perfect climbing bike.

-This frame requires a zero-dish (hub offset to the driveside by 5mm) rear wheel and you can *only* run an outboard position (~56mm chainline) ring. That means no crank mounted bashguard (ISCG can be done, though) and no front derailleur. XX1 cranks are a no-go. A Rohloff hub could work reasonably well as they use a 54mm chainline if you are a planetary gears kind of person.
EDIT: Actually, with a 28t MRP bling ring running at 51mm chainline, XX1 will work. In theory you could avoid the offset rear end here.

-Even with the whole rear end moved outboard to line up with the ring the chainline is not especially good in the highest or lowest gear. The stays are so short that the angle just gets extreme. I've had good luck running 9 out of 10 cogs on a 10 speed cassette, which is plenty for me, but those who want a full range will not be happy with the drivetrain performance. Singlespeeders will have no problems. EDIT: With a 28t Bling Ring, chainline is much better and I get full use of all 10/11 gears.

-Tire clearance is somewhat limited - a 2.3 will fit fine but anything bigger is a tight squeeze. Adding 5mm to the chainstays or using an 83mm BB shell (which brings another set of issues that I won't go into now) would take care of this.

So bottom line: I love this bike. I like it even better than my previous short-stay setup from a few years ago and for the right rider (ie more interested in having fun on 2 hour rides than absolute speed or 24 hour solo sufferfests) I think this sort of geometry is a great fit.

I should also note that the new Paragon Polydrops (which Mark asked me to test prototypes of with this frame) are working great after probably 15 hours of riding and I'm happy to build with them (no extra charge) for anyone who is interested. They are probably not the ideal dropout for this bike due to their length (makes it hard to use the second bend on s-bend chainstays to get any heel clearance) but they offer some cool flexibility in terms of bike setup and I have had zero problems with them thus far. Most riders may prefer the low mount or classic DR2010 (or sliders for the singlespeed crowd) but that's a decision that's complex enough that I'm not going to go into it here.

Don

Don's mostly a singlespeeder and he's got a SS I built for him 7 or 8 years ago, but he wanted a geared bike with a suspension fork for longer, rougher rides. Or maybe he just got old and lame like me and figured out gears and suspension can make up for creaky knees and wrists a little.

In any case, it's a big bike for a tall fellow, built to handle everything the Wasatch can throw at him. Geometry:
-69.5 HTA, 73 (effective) STA
-For a 100mm travel tapered steerer fork
-65.5cm effective toptube, 71.3cm front center (yeah, that's long!), 93mm trail
-43cm chainstays, clearance for a 2.4" tire, no front derailleur
-Curves (toptube, seat tube, stays) for tire clearance and fun.
-32.5cm/12.8" BB height (Don uses 180mm cranks and doesn't like to hit his pedals on stuff)
-Supertherm front end mostly with Deda chainstays and trusty Paragon DR2010 dropouts. Frame weight is about 2300g.

So basically, a bike built for all-around XC adventure, on the stable side for long days in the saddle and rough terrain. Should be a blast!

Nick, this picture is for you - big as a garden gate, as you like to say!

More belt drive thoughts

A fun weekend is almost behind us - I am finally not sick, and (kinda) not broken, so I was actually able to bandage up my bum wrist and go for a road ride both Saturday and Sunday. Sweet! It's not improving as quickly as I'd hoped, so I think mountain biking is done for the year, but if I can get out on the road at least, I can keep my sanity.

Spent some time this morning playing with belt drive parts and plotting. After looking at the info from Spot, and mounting up the drive cog/chainring on an LX crankset (ie, 50mm chainline) to do some real-world visualization, it appears to me that I can, with some tubing manipulation and trickery, manage to build a singlespeed 29er with 445mm (or about 17.5") chainstays, clearance (just barely) for a 2.1" tire, and clearance (again, by the skin of my teeth) for the chainring thing. It's not anything like what's doable with a chain, of course (you could probably get the stays down into the 425mm range pretty easily) but I'm a big guy and really prefer the stays in the 440-450mm range as it is.

This is a good sign, because last I looked at it (without actually mounting anything up) it really appeared to me that there was no practical way to get any kind of mountain bike tire onto a belt driven bike without making the chainstays super duper long (this is the solution that Spot seems to be using - 18.5"+ chainstays) or doing something really weird with elevated chainstays (barf).

I'm cautiously optimistic that it's doable - but it'll require several tweaks:
-2mm spacers between the crank spider and the chainring/cog to offset the beltline outboard and make extra room. Yes, this is a little bit sketchy as it puts all the force on the bolts instead directly onto the spider, but I think it'll be fine.
-Fairly significantly crimp some S-bend stays for tire clearance (this will get me another 2mm or so on each side of the tire). I do this anyway on a lot of bikes, but never bothered with my current singlespeed, because I don't personally want super short stays or huge rear tires.
-Narrow the tire clearance (at the widest point on the knobs) to somewhere around 60mm. This of course leaves very limited room for anything bigger than a ~2.1" tire (no Weirwolves on the rear of this bad boy) but since I hate using big tires on the rear anyway, it shouldn't be much of an issue. I just better hope there's no mud...

In any case, it's looking like I might actually start this project in the next few days, so stay tuned if you're interested in this sort of thing. I'm also attempting to do a seat tube that will take a 30.9 (Speedball!) seatpost, as well as a few other fancy bits. My loss (wrist injury) is your gain (more framebuilding posts), loyal blog readers!

And yes, I'm aware that this is several consecutive posts with no pictures. Sorry. I'll try to do better.