Stick a Fork in It

Surly Pugsley Fork

I have been piecing together a mountain bike — a sort of prototype to decide what I really want.  So far I’ve selected a 9:zero:7 frame which will use Shimano alfine hubbed wheels.  To complete the basic frame, I need a fork.  The fork that  makes the most sense is the Surly Pugsley fork — so I could run a single speed rear hub as my front wheel, and in the case of a hub failure I could swap front and rear wheels and go on Singlespeed style.  My other options were the Salsa enabler, Carver TI and Carbon Fiber O’Beast forks, 616 Fork, and various other takes on this.  

The first decision is whether I wanted or needed front and rear wheel interchangeability.   While it would be nice to have given the mixed reporting on Shimano’s Alfine hubs — this bike is being put together for what I think will ultimately be setup with a Pinion in frame hub, where the rear wheel is a singlespeed.  The likelihood of singlespeed hub failure is pretty low, so that would move it into the nice to have but not a necessity column for me.  So I revisited my initial criteria for the bike:

  • Comfort over Speed (I am not doing insane Downhill/Freestyle flips in the air)
  • Fun — some bikes just make you feel like a hooligan and I want to be a hooligan every day
  • Practical — I need to be able to use this for grocery shopping, single track, and maybe even a trailer from time to time.

Comfort screams for a suspended fork, but practicality does not –as most suspended forks remove the possibility of using a front rack with panniers.  Luckily many great handlebar mounted bags have been released for mountain bikes (I even found some slick looking baskets :)).  The only problem is there is no fork that fits the fat tires or even semi-fat tires that the 9:zero:7 frame I purchased is capable of running — and that is one of the items I want to experiment with.  I found two options: one involving sandpaper and a modified standard fork, the other being a Cannondale Lefty with a new set of clamps which  offset the wheel a little more to allow the width needed, while the lefty by design has loads of clearance.

The clamps, offered by Craig Smith at Mendon Cycle Smith offset the wheel by 17.5mm.  This is important because that is the same offset as my rear wheel, so while I cannot field swap the wheels, any rim that would lace for the rear will lace for the front.  So this will give me some additional give when running fat tires, as well as making things more compliant if/when I run 29er or 26″ normal MTB tires.  In order to get setup for this, the right parts need to be accumulated.  Craig sent me the following for selecting a donor fork:

The set up requires use of the older movable clamp style for Lefty, so a modern OPI upper, bonded clamp, or carbon, won’t work. There are a huge number of these forks out there though, and due to being inexpensively serviceable, a fork found unusable, can generally be brought to factory fresh, ridable condition for around $100.

2001-2004 Lefty DLR/ELO, Titanium axled forks are a good choice with 100mm original travel (tuned to 70mm for fat use), and an axle to crown of 480mm.

2005-2007 Lefty Max 140mm FFD/TPC/SPV alloy’s are the flexible choice, as they can be used in original configuration, or, drop a modern 2012 Cannondale PBR or XLR damper in, and have the choice of 110-70 mm of Fat travel, and axle to crown of 520 to 480. Anything in between is possible too, allowing for exact wishes to be met, this set up nets a fork at 4.67 lbs, or 2100 grams with an uncut steerer.

To make my decision to go suspended or run a pugsley even easier, I found a 2001-2004 DLR that had been serviced by Craig and setup for fatbike use.  So I will use that for now.   All I needed to provide Craig was my stack height including headset (no stem) and some money!  The only downside is that the DLR  fork has less travel than the de-traveled Lefty Max — so that is what I will likely use  for my final build as I accumulate the parts necessary.  I am planning on getting the 140mm Lefty Max and dropping in the modern PBR damper, which will require these extra parts from the 2012 Lefty Max manual:

  • KH062 — PBR 140 Damper
  • KH088 — Solo Air
  • KH064 — Upper Collar for PBR
  • KT028 — Lower Air Plug

These parts are not required to use the damper, only to upgrade the internals to 2012 spec parts.

The only question regarding using front suspension, in particular the Lefty is rigidity (everyone knows forks need two legs) and durability. The first question is answered here:

The second is answered by the Cannondale riders that have used the Lefty in the Tour Divide without issue — including organizer/multi-year winner Matt Lee.  That said — the one downside is the bearings need to be reset — something easier with the newer PBR dampers — and something that only takes a few minutes and is recommended every 25 hours of riding — though some reports go 50+ hours.  Not resetting the bearing will only result in travel limiting from what I understand, and not damage of any kind.

So there it is — I now have my frame, fork is on the way, hub is being built into the wheels, and I might even have a complete bike by the weekend!

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