Basically I think the BD setup with rigid fork is a perfect idea (and was exactly what I wanted). There is no need for suspension at the BD at least for my way of riding (touring on- and offroad, every day riding). However, I am experiencing two issues that I am a bit picky about.

1. Handling of my BD when riding turns: I have no idea whether this is a matter of tires, steering angles or fork specification. Surly setup looks perfectly alright. I cannot see any technical reason for this in frame geometry. Nevertheless, when riding fast turns with quite some slope, there is some sort of oversteering. Handle bar (or tire?) tends to take the turn harder and harder forcefully, no matter whether applying brakes or not. My BD does not just run through the bends in a neutral way as one would expect (my MTB or road bikes handling keeps neutral when riding turns with slope). I have not yet experienced such behaviour with previous bikes, regardless of tire thickness, but I have never been using Fat Frank tires with their special shape before. I have got an 18″ frame using a dainty hope headset keeping front low.
2. Combining rigid fork with disk brake: Apart from quick release axle issue, (see disk brake page) there is some more thing I would like to point out. When using brakes under certain circumstances fork might start building up oscillation in longitudinal direction somehow. Something I have never realized with disk brakes up to now, even at some previous rigid fork setup in another bicycle. It happens when braking on ripples or when using brakes in turns and trying to modify the curve radius. These actions will be taken up by fork which will start swinging back and forth (at least it feels as like), and brake lever needs to be released to calm it down. It is not just like using brakes on uneven ground, as like everyone is used to with ordinary MTB riding or so. In my opinion this may be a matter of rigid fork not being able to vertically absorb initial strong brake impulses on the one hand and riding impacts on the other (concurrently), making it start to oscillate. Maybe this is a matter of thick tire springiness lacking any dampening. Within the last 2600km of BD riding I had it twice, both when riding downhill tarmac roads with nearly no load. Second experience happened today in the morning when I took a tight turn with brakes applied and had to go even tighter which let fork start shaking.
   Brakes (2008 XT hydr. disk) provide strong, clear and smooth operation. There are no noises at all, no vibrations, nothing. Also, there are no issues with irregular brake power, bad rotors or anything.

I am currently thinking about testing my pace RC40F suspension fork (130mm of travel) at the BD to address both issues. It might absorb or dampen sharp braking and riding impacts and could probably prevent what I called fork oscillation. Also it will considerably change steering geometry and thus could resolve handling issue. However, these issues may very much be related to the tires used, so I should probably start experimenting with different tires as a first step.

Björns blog article describes a new and interesting Big Dummy build up project starting right now. His 20″ frame was announced to arrive today. His assembly kit includes heavy duty sports components as like Magura Gustav M downhill brakes in combination with Shimano Alfine internal hub and hub dynamo for allround and offroad usage. I am really curious how it will work. Check his complete blog for any further information. Björn, have fun with it!

Big Dummy naked, showing fenders, tires, rear details

Basically the BD frame builds up straight forward without any concerns or caveats. Get yourself some long cables, liners and wires and start. Here are just some small issues I encountered when building up the big dummy at home. Please have a look at Surly Spew for the real important topics of it.

Disk brakes

Handle bar setup with XT disk brakes, cabling etc.

• When using disk brakes, take care you can get some rear brake tubing of probably 190cm in length. Magura offers up to 250cm, Shimano does not. With my 2008 Shimano XT disk brakes I had to use replacement tubing. I had a 250cm Magura liner in my toolbox, so I cut off Maguras fixed end and installed both ends with Shimano olives and Shimano hex nuts.
• At my forks IS2000 clamp, the Shimano caliper needed some more radial offset since there was not enough clearance between disk and caliper. Luckywise the caliper uses postmount standard and therefore I could insert some spacers between caliper and postmount adapter. I have no idea how this could be fixed with some IS2000 caliper.
• Take care for freeloader bag! Put some protective material at the inside of the left freeloader bag, where it hits the caliper. At long downhill sections it might get too hot for the nylon material. Or better use the quite expensive Xtracycle disk mount kit pretty well pictured in this nice BD build to protect freeloader bag from hitting any hot brake parts.

Tires and fenders

Front view

• Surly permits use of 2.5″ tires. With Schwalbe Fat Frank 2.35″ I realize there is enough lateral tire clearance, but it gets very tight at the rear end of the frame since this type of tire has got quite a high profile. Maybe this is the reason why it offers great riding comfort while being quite fast on the other hand.
• Mud catchers: frame and fork offer several thread eyelets for different purposes. I use SKS Bluemels, ATB version. These are lightweighted adaptive mudguards made from plastics fitting most 26″ bikes. Tire width should not exceed 2.25″ according to SKS, but it fits 2.35 Fat Frank tires on 30mm wide Subrosa rims as well, as shown in picture below. There is not much clearance in between, but it works. At the left side, I cut away one of the holding stays since it collided with brake caliper. It would easily be possible to mount it above the brake caliper since there are some more eyelets, but I decided to leave those for later usage. Front guard mounting is visible in the picture to the right. Take care there are safety clips installed at the front fender stays allowing them getting ripped off from eyelets, to avoid wheel blockage in case some stuff gets in between tire and fender.

Drive train

• The BD can be driven every way you like, but I prefer internal gear hubs. While Rohloff is too expensive, NuVinci is very interesting but too heavy and SRAM i9 is too heavy compared to Alfine, I chose Shimano Alfine 8 speed hub (1600g) with a 20 teeth sprocket. This hub is quite cheap, looks nice, seems to be durable and fits the frame, although the dropout slots are a bit too small for the anti torsion spacers. It could easily be used in combination with a dual crankset and front deraillieur, since a chain tensioning device is needed anyway due to vertical dropout slots.
  Nevertheless, for me it works with single chainwheel and 8 gears, and I do not even need a long shifting cable since Shimanos standard length of 210mm will fit by far. I believe it is nice to have only one cable instead of 2 for Rohloff or NuVinci, just for simplicity. Removing the rear wheel is slightly more messy, on the other hand.
• Although being 173cm in size, I am using short cranks of 160mm length. At the BD this is of advantage due to low ground clearance when going slopes and riding offroad and bumps. I may recommend Token bottom brackets made from carbon and steel. These are lightweighted and up to now appear to work completely silent without any cracking noises. In Germany you may get them for instance at Radplan Delta together with fine and lightweighted cranksets from TA Specialites or Sugino or many others. With a 34 teeth chainwheel I am capable of riding uphills at 15-20% and even more, strongly depending on the load, and it is still possible to pedal at speeds up to 40km/h.

Xtracycle

The Xtracycle rack is mounted losely. There is no fixed connection holding it in place. Since I do not like the lateral sloppyness of the V-racks, I wrapped some tape around its exterior tube sections before plugging them into the rear frame extension. This way the V-racks will stay in place a bit better and sloppyness is reduced. Also, as suggested by Surly Spew, use sections of thin bicycle tube covering the connection sections to avoid water, rain and dirt getting into the frame tubing where V-racks are mounted.
Nevertheless, always use some strap to connect V-racks to each other, no matter whether snap deck is mounted or not. When riding out of saddle and swinging the bike laterally your load might behave badly otherwise.
I have mounted a child seat on the snap deck. When using it, I fix it by a strong strap connecting it to the V-racks and being pulled firmly. Also I have several leather pedal straps for multiple purposes as to my needs.

Bicycle electrics

To me it sounds very reasonable to put lighting equipment on a cycle like the BD. Apart from being obligatory in several countries, there is no way around it when riding at night. Since I do not like messing around with batteries, I installed a SON dynamo hub with LED rear- and front lights and firm 2 wire cabling. Everything works without batteries. There is light even when bicycle stops. The Xtracycle V-racks are a perfect place to mount a tail light and some reflecting stuff. The headlight is mounted at the usual location at the fork.