So by now you’ve hopefully read through PART 1 of this Fat Bike Saga. Welcome back – if you haven’t though, you really should read that first as it gives you some back story with where I have been, and how I came to arrive where I am now. Up above is where I am now and as noted in the previous post, below in the next 4 images is my Fat Bike Prototype #3. I rode this throughout the entire season of 2013. I built it using Paragon Machine Works Sliders to really hone in on chain stay length and wheelbase as it related to two different wheel sizes (5″ fat and 29+) as well as what happens when conditions change throughout the season of winter and snowfall, is there an “ideal” chain stay length coupled with head angle, bottom bracket height and tire size? What’s interesting is I started long, went short and then kind of fell somewhere in the middle. What I really found was that when the wheelbase got shorter, the ride naturally got a little more choppy, traction was good, but handling wise, it felt as though a little more length would help to stabilize the handling characteristics in snow. Shortness didn’t really equate to the quickness that is related when out on dirt like it does on a 29er for example. The biggest factor was really dialing in where the riders center of gravity needs to be. Lowering the bottom bracket even more in the above build made a huge difference getting myself physically even MORE into the bike. I found by lowering the saddle height, I was figuring out where the saddle really needed to be in relation to the bars for me, and with this build, I could get it where it needed to be and still get proper leg extension. But again, more set up refinement from brakes, to cranks, chainring choices and tire choice and air pressure.
You can see how things really started to get dialed below:
The big thing with this one above when compared to the next beast I’m about to show you is rear end spacing, fork setup and head angle (I think I’ve got the bottom bracket drop nailed). You’ll note that I’ve swapped over to flat bars from risers too. Still sporting mechanical actuated disc brakes. Why? Hydro’s have been known to stick or become slug gist in really cold weather and yes, I’m out there when temps dip well below 0. I want my brakes to work when I need them. A big part of riding in cold weather and snow is also your gear setup on your person. (I’ll get into this one sometime this winter btw.) With setting up all the tooling for fork production, I am now not beholden to what is on the market – now I can create exactly what I need to deliver the ride characteristics I want given the terrain and usage. So here goes nothing:
Right out of the gates we’ve moved from 170mm rear axle spacing to a 190mm rear axle spacing powered by Industry Nine Torch Hubs mated to HED’s Big Deal rims (Tubeless…). This is an 85mm rim and really opens up the tire profile. That 5″ tire now is a monster – if it wasn’t already! Race Face’s Turbine Cinch cranks sport a spider less 30t chainring (will be ridden with both a 30t and 28t setup as I want to see what the best balance is for this new to me XX1 1×11 drivetrain). Race Face’s cinch platform actually has two spindle options for both 170 and 190mm rear end spacing. Out of the box, these suckers mount up smoothly, an offer GOBS of clearance between chainring to chain stay, and crank arm tips to chain stay. The spindle on the 190mm version is massively long. So much so, I could have honestly given myself more clearance at the chain stay / tire area (next time right?). The I9 sports an XD driver to accept Sram’s XX1 cassette. Top end is a 42t cog and mated to a narrow wide chainring and appropriate X1 rear derailleur which has the same tooth profile… AND has the correct chain line, any chance of tire rub to chain is absolutely gone. Chain crossover from the previous version is just not present like it was (another thing to note with shorter chain stays…). Bottom bracket is low. With sag in tires compensated, it sits around 11.25″. Parking lot we’re looking more like 11.5″ bb height. Yeah. That’s low for this neck of the woods but it really sets the stage for technical trail riding IN THE SNOW. Head angle was slackened up, and I moved from a 450 axle to crown measurement up to a 460mm A2C. A little change brought the bars almost dead even with the saddle. Gone are the sliders. Hope does duty for keeping the wheels in place while Avid BB7’s do time with stopping power. Simple. Clean. They work in any temp’s and they’re black…
Fork is sports a tapered steerer. Chainstays are flattened for added lateral stiffness and both are formed appropriately to add heal and tire clearances. Internal cable routing keeps the top tube running clean. Head tube is matching 44mm. And what’s this? A Cane Creek 40 Series head set? Actually, I have a Cane Creek 110 sitting here as it’s replacement. But here’s the story on that: I had a King I7 in there before. Swapping parts from the previous guid it seems that the top cap cover assembly just would not want to let go. A mallet was involved to get it to break it’s death grip… Everything went back together easily enough but when it came to putting that top cap cover assembly onto the new set up, the green rubber o-ring JUST WOULD NOT COOPERATE with me. I think I was at it for over an hour even making a special shim out of composite material to help compress the o-ring back into it’s position and maybe JUST maybe, get the heck out of the way and let me slide everything back together. Well… that just did not happen. So out came the King (almost threw it out my back door as far as the eye could see) and in went the old trusty, beat to hell but still working smoothly Cane Creek 40. And you know what? That top cap cover which sports a slightly different o-ring compression assembly slipped on slicker than snot. So thank you Cane Creek. I am now officially a REALLY loyal customer (don’t get me wrong-I’ll put a King on for you if you must have it, but from here on out, I’m pushing Cane Creek…). So that clears up that debacle.
But here’s the funny news: I found that a chain stay length of 17″ both in snow as a 5″ fatty and 17″ as a 29+ trail bike kind of were the best of both world scenario. Wheelbase was long enough to maintain good stability in snow, but with 29+ wheels in place, I found that the choppy feel was gone and there was this incredible “smoothness” that appeared. Like buttery smooth and very unique in combination with that lower bottom bracket height. This really set the stage last season for how this bike above was forged. What I’ve been doing is slowly stretching out the wheel base, lowering the rider center of gravity, pushing myself down and into the bike and getting that front wheel out in front of me to promote that float. With all this the spec of components has really changed dramatically as technology AND options for fat bikes really has come to reality. Much lower tooth count chainrings are available with a really diverse cluster of cogs in the rear. 190mm spacing for 5″ tires gets the tire rub issues and chain crossover issues wiped clean (chain stay length also played a big role here too). Yes that tire is getting close to the seat tube, but again, there is still lots of clearances down there in every which direction (image is deceptive, but above the tire is more in line with how the clearances look all the way around the tire):
In summary: I can’t wait to ride this bike when the snow comes. The snow naturally can wait. But I’m feeling really ready and confident with this refined set up this season. Flat pedals (45 North Helva Pedals) will be employed – not the crank brothers you see in the pics. A left over from displaying this bike at the New England Builders’ Ball and naturally, forgot to swap them out when I took the pics! The real big things to consider when looking at all these fat bikes I’ve built is this: Bottom bracket height, wheelbase, chain stay length, saddle to bar height comparison, tire size and tire pressure, head tube angle, rim width, rear wheel axle spacing depending on tire size, and last but not least: TIRE PRESSURE. Out of all these, if I were to pick a top 3 in order it would be: Bottom Bracket height in relation to rider center of gravity, head tube angle in combination with fork rake/length and tire width in combination with pressure as per conditions. Those 3 in that order have the biggest impacts on how a fat bike handles. From a “stock” look, the rider has more control over the setup, wheel choice, tire choice and tire pressure as well as drivetrain gearing. You can really dial things in just with the component spec actually no matter what the actual geometry is.
My spec has been pretty nit-picked and dialed over the course of several seasons. I also was refining my approach too as new components and needs actually came into production, so in many ways, what I’ve been doing was sort of at the fore front of what was available at the time and what I had at the time. As things became available like true 1x setups, larger cassette cogs with more teeth, bigger, wider tires with more bite, wider hub spacing, etc. I was able to incorporate that with what I was building immediately. Build. Ride. Repeat. In that order. But what you see is years of selection, use, refinement and more use. I choose components that work for what I’m riding. Carbon takes the sting out of the contact points so it’s a must for me on all my builds when it comes to handlebars and seat posts (ENVE is the only choice IMO). ODI Yeti Lock-On grips offer a really aggressive and soft compound that is tacky enough to work in many conditions, but soft to keep my hands happy for long miles. They wear well and don’t twist. These are made in the USA. (Look closely, it’s printed on the grip). Thomson takes care of stem duties with their X4 mountain stem in a 90mm / 0 degree rise offering. Black. Simple. Beautiful. Made in the USA. Saddle was a bit of an experiment but I’ve come to like Selle San Marco’s Zoncolan. Salsa keeps my seat post from slipping and I typically swap this one out in the winter for a quick release type just in case I ever need to drop the saddle to gain a lot of traction when conditions change that much where tire pressure changes, and weight distribution changes are at their limits. Tread wise, Surly’s Bud/Lou combination is THE combination. I know Schwalbe has a tire out, but first glance the knobs look like they are very spaced out – is that a lot of dead space and traction issues? Don’t know. But maybe I’ll get a set and try them out. Maybe not. Drive train this one’s a Sram 1×11 (and a mix of X1 and XX1). I’ll test out different chainring sizes and tooth counts throughout the season. I’m really curious about the ability to go tubeless with this setup and what that means regarding losing an extra 2 pounds which puts me into the 27-28lb range… That’s a game changer right there with how this bike will ride and feel.
So yes, there’s more to come. For now, over the course of several seasons of riding straight through the winter and into the spring, I’ve tuned, refined and honed each build to perform better than the last and passed on what I’ve figured out to my clients. I’m just that much more informed when someone comes to me with a set of wants and needs, I can stand on my own experience and help steer them towards Fat Bike bliss and hopefully, to look for short cuts of their own…