Dissecting the Surly ECR

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Above: An off-color Surly ECR on the AZT near the town of Pine.  The ECR continues in the tradition of Surly’s adventure touring bikes, including the Troll and Ogre, each of which fulfill some of the promise of early mountain bikes, once clad with useful features since forgotten on many modern machines.  This frame is a different shade than those being released this week, also shown with 29×3.0″ Knard tires mounted to ‘skinny’ rims, a temporary situation.

Introducing the Surly ECR

The Surly ECR is an off-the-beaten-path touring bike designed for 29×3.0″ tires, dubbed 29+, a platform first released on the Surly Krampus last year.  The frame features attachment points for racks, fenders, water bottles, and lights.  The geometry is characterized by a low bottom bracket and long chainstays, for a supremely stable ride, with or without a load.  A short top tube affords a comfortable upright position for long days in the saddle, a touristic vantage, and a good climbing position.  Versatile rear dropouts allow a conventional derailleur system, an internal gear hub (including a unique mounting point for the torque arm of a Rohloff Speedhub), and singlespeed or fixed gear systems.  The frame accepts normal hubs, bottom bracket, and headset.  Three-inch tires– the main feature of the bike– provide an assured, lightly suspended ride, offering traction and flotation on a variety of surfaces.

However, with some sweat and imagination, the ECR could be: a personal escape vehicle for overnight rides into the mountains; a comfortable long-distance Great Divide tourer; a cast iron and case of beer hauler for you and your friends; a sorta-fatbike for those few winter days where you live, when things pile up more than an inch; a sorta-fatbike, for the BLM ‘road’ that spends more time in the arroyo, than out of it;  the bike that puts your other bikes out of work; the reason you don’t need suspension on tour; or, the reason you absolutely need to go somewhere you’ve always dreamed.  On paper, it’s a practical rig with a promising host of features.  In person, it simply asks to go somewhere.  The ECR is an exploration camping rig, nonpareil.

The ECR is designed to go almost anywhere.  However, there are a few technical caveats for the would-be ECR owner to consider, including:

3.0″ wide tires, which require some special equipment to engage a full range of mountain touring gears

-a low bottom bracket, which promotes stability at all speeds in all conditions, but limits the capacity to fit ‘normal’ sized 29″/700c tires, without challenging pedal-to-ground clearance

-traditional headtube dimensions, which abide by the longstanding 1 1/8th inch standard.  But, future suspension forks with 3.0″ tire clearance will likely feature tapered steerer tubes, and will not fit.

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Frame highlights:

The ECR frame features larger-than-normal 3.0″ tires.  Normal mountain bike and touring components can be used throughout the bike– unlike most fatbikes– with a few exceptions.  The crown jewel of the frame construction is a one-piece chainstay yoke that provides clearance for a 3.0″ tire and a full mountain bike crankset.  That is, the parts technically fit onto the frame.  But in use, modern double or triple cranks will force the chain to rub against the tire in the easiest gear combinations (no clearance issues exist when using standard sized 29″ tires in the frame).  Several solutions exist to avoid conflict, such as using a 1x drivetrain, an offset double, or an internal gear hub.

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Cro-moly steel tubing is used throughout the frame and fork, with more attachment points than is common on even the most full-featured tourers.  The frame is ED coated to resist corrosion.

Eyelets at the top of the fork blades allow the use of a top-mount rack up front.  Mid-fork eyelets support a low-rider rack, while triple water bottle mounts behind the fork blades are meant for normal bottle cages, or the Salsa Anything Cage and its descendants.  The main triangle features three water bottle mounts, including one on the underside of the downtube.  Of course, a framebag is the best use of space inside the frame.  Look for Revelate bags in stock sizes for the ECR soon.

Don’t be fooled, the frame is not built with Reynolds tubing.  This sticker advertises the Bikeworks shop in Albuquerque, NM, in the (505) area code–  a brilliant shop sticker design.  The clutter of extra wires connects a Shimano dynamo hub to a Supernova headlight and taillight, and a B&M USB-Werk, which supplies USB power to a Garmin e-Trex 20, and other devices.

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Rear dropouts– a precise clusterfuck– to serve all drivetrain needs.  This configuration allows the rear axle to be adjusted horizontally for a custom effective chainstay length, or for tensioning the chain when using an internal gear hub, or singlespeed drivetrain.  The long slotted attachments in use below, are to adjust the disc brake caliper, in concert with the hub.  The lower slotted attachment is for the torque arm of a Rohloff hub.  The largest threaded hole, with the array of pinholes surrounding, is designed specifically for the Surly Bill and Ted trailers.  I’ve installed Surly Monkey Nuts into the dropouts, to fix the axle location 14mm rearwards.  These lightweight machined dropout spacers are helpful when using Surly’s rearward facing dropouts with disc brakes, when you choose not to install the wheel in the extreme forward position.  For help tensioning an IGH hub or singlespeed system, look for the Surly Tuggnut.

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Gearing for 29+:

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Accommodating a wide range of gears and a 3.0″ tire is not always as simple as swapping parts from an existing mountain bike.  Several solutions include:

1.  A 1x system, which utilizes the middle position of a standard mountain bike triple, allowing a ring down to 32t (30t is technically available, but uncommon).  If a 32t chainring and a 12-36t cassette suffices, this is the simplest solution.  Using a smaller single ring, such as a 22t ring in the inside position, may result in a chainline that runs very close to the tire, or may even contact the tire.

2.  An offset double crank is available from Surly in two models.  A new two-piece Surly Offset Double (OD) crank affords the use of the 64mm inner BCD and the 104mm outer BCD, the two common bolt patterns found on most mountain bike cranks.  The crank comes stock with 22-36t rings, a useful combination.  The Surly Mr. Whirly crank has been available for several years, and is designed to be fully customizable from single to triple ring set-ups, with custom spindles for both 68/73mm and 100mm, for fatbikes.  An offset double spider is available for this application, the same that has been used on the Moonlander and Black Ops Pugsley for several years. Note: some riders report success using dedicated mountain double cranks, such as a Shimano XT model, without interference, although tires may not have been mounted to 50mm Rabbit Hole rims.

3.  An internal gear hub (IGH) uses a single chainline, which does not interfere with the tire.  The Rohloff Speedhub is the most durable and reliable IGH available for extended, off-pavement applications.

4.  Singlespeed and fixed gear drivetrains will work just fine, although beware that using the inside position of a double or triple crank may cause similar interference, as described above.

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In a pinch, I constructed a custom offset-double crank out of a pile of used parts, sourced from Two Wheel Drive in Albuquerque, NM.  The Frankencrank features mismatched crank arms, a 68mm square taper cartridge BB in a 73mm BB shell with a stack of spacers on the drive-side to create additional chain-to-tire clearance.  A bottom bracket mounted e-type front derailleur is used for front shifting, as a normal front derailleur would not reach when mounted to the seat tube.  The system is working for now, but is not officially recommended.  A long spindle 73mm square taper BB could be a viable solution for the adventurous home mechanic.  Best of all, buy an offset crank from Surly, or choose to use a 1x system or an IGH.

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Tires and suspension:

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Adjusting tire pressures to changing terrain is essential to getting the most out of the 29+ platform.  Lower tire pressures conform to the trail, providing comfort, traction, and flotation.  Tubeless wheel systems allow lower pressures, without the risk of pinching a tube; wider rims support tires at lower pressures.  The ECR is offered with 50mm wide Rabbit Hole rims. While Surly rims and tires can be set-up tubeless, some old-fashioned tricks may be required, including building up the rim bed to help ‘seat’ the tire, or using the “split-tube” method (also called ghetto tubeless).  For this reason, rims designed to be used tubeless may be preferred, such as the Velocity Blunt 35 (35mm wide, formerly the P35) or the new Velocity Dually (45mm).  Surly recommends a rim no smaller than 35mm for 3.0″ tires; as I’ve shoehorned my tires onto 29.1mm Stan’s Flow EX rims, I can attest that a wider rim would better support the tire, allowing lower operating pressures without risk of rolling the tire, especially when trail riding with a load.  As a final tubeless note, the 27tpi tires available from Surly should be more resistant to sidewall cuts, a hazard known to tubeless users in rocky country.  Thankfully, the 27tpi tires are also cheaper than their lightweight 120tpi counterparts.

While 3.0″ tires offer some suspension from the trail, the undampened effects of a big tire on rocky trails will have some riders looking for a suitable suspension fork, to avoid bouncing from obstacle to obstacle.  Modern suspension offers adjustments that cannot be matched by a simple balloon tire.  Unfortunately, there aren’t any suspension forks currently manufactured to clear a 3.0″ tire, officially.  Internet research may lead you to some models which barely clear the tire (some Fox forks, esp. thru-axle models, for instance), while others have modified their forks by shaving material from the underside of the arch.  As for a fork that officially clears a bigger tire?  There are rumors of a release, but most likely, it will feature modern dimensions including a 15mm thru-axle and a tapered steerer tube.  The straight 1 1/8th head tube on the ECR will not accept a tapered steerer.  The Krampus, however, will take a tapered tube.  The 80mm suspension-corrected steel fork on your ECR may never have a worthy hydraulic successor, at least not without some unofficial fork mods.

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ECR Geometry:

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The ECR is not “just a Krampus with holes”.  The geometry of the ECR is much like the Surly Ogre (or even the Salsa Fargo), adjusted for larger tires.  As a result of larger tires, the ECR features longer chain stays, and a greater nominal BB drop, which is the measurement from the BB to the imaginary line between the bike’s front and rear axle.  The Ogre claims a 68mm BB drop (Fargo, 70mm), while the ECR claims 80mm.  Comparing these numbers in relation to the intended tire sizes for these bikes, this puts the BB in almost the exact same place above the ground on both models– this relative measurement from the ground is called the BB height.  Thus, while you can put smaller 29″ tires on the ECR, the BB height (the measurement from the ground), will be about 10-15mm lower than with the 3.0″ tires, exactly 12mm lower than with the exact same tires on the Ogre.

Running ‘normal’ 29″ tires on the ECR: Even with relatively large-volume tires such as the 29×2.4″ Maxxis Ardent, the ECR will suffer from such a low bottom bracket to exclude any real trail riding, without risk of frequent pedal strike.  On paved and smooth dirt roads, a lower bottom bracket may not be a major hindrance.  But if trail riding is in your future, and choosing from the vast range of 29″ tires is appealing to you, consider the Krampus, which claims a 60mm bottom bracket drop.  Even with 29×2.3″ tires, the Krampus still offers generous clearance on rough roads and trails.  Of course, pedal clearance is also dependent on the type of pedals used.

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With so many adventure touring bikes available, it can be hard to decide which to choose.  For additional perspectives, consider the following resources regarding the aforementioned Surly frames:

Pedaling Nowhere– Logan has recently built an ECR for an extended tour in Africa.  Read his first impressions from the build process, and follow along for updates from the road.

While Out Riding–  Cass has ridden the entire line of adventure touring bikes from Surly, including the exact ECR frame that I am now pedaling.  Troll or Ogre?, Ogre or Krampus?, ECR?— he’s surely got a few days and miles on these bikes.  It only makes sense that a Pugsley is next!

VikApproved–  Vik has been riding a Krampus for nearly a year, mostly around BritishColumbia, and has past experience with fatbikes and IGHs.

Big Dummy Daddy–  Andy has written one of the most thoughtful reckonings of the ECR, and 29+, anywhere on the web.  His experience with fatbikes, and nearly 30 years of mountain bikes, plays well with some foresightful theoretical perspectives about the future of the 29+ genre.

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