Archive for the ‘wetmorian#1.1’ Category.

Gifford

The TODO list is getting short, and got short enough for me to build it up for some shakedown rides. Remaining on the list:

  • Wire guides for the headlight
  • Racks (this one is borrowed from my RB-T)
  • Paint

A couple of small details. This is how I routed the cables to the Rohloff (always a little tricky):

The wire guides are cut up and bent pieces of a spoke. I liked them better than the commercial guides that I could find. Running the cables over the bottom bracket and then around the inside of the chainstay gave me a much nicer cable run than under the bottom bracket (which is very large on this bike).

Tire and crank clearance came out just about perfectly. A 2″ or 52mm knobby fits and so do my lowish Q-Factor Ritchey cranks.

I removed the big ugly Rohloff sticker from the hub (now that my warranty is expired):

It weighs 30# as shown. A little chunky, but not too bad fora Rohloff’d bike with fenders, racks, pump, water bottle cages, etc.

I’ve named it Gifford in honor of Gifford Pinchot, since I expect that this bike will spend a good amount of time (and the most enjoyable time) in National Forest lands.

Brief set of geometry specs:

  • 55cm seat tube (actual), 58.5cm (virtual)
  • 57cm top tube (actual), 58cm (virtual)
  • 5 degree top tube angle
  • 73 degree head tube angle
  • 72 degree seat tube angle
  • 60mm fork offset, for a hair under 40mm in trail
  • 44.5cm chainstays
  • 9/6/9 True Temper Verus main frame tubing, Dedacciai COM12.5 fork blades,Nova Cycles bent/ovalized chainstays
  • Rohloff hub
  • Easton Eccentric bottom bracket
  • It will get a Schmidt 20R front hub,but right now it has a Shimano DH-3N70
  • Shimano BR-R550 Canti brakes
  • Grand Bois Hetre tires with Velo-Orange 52mm wide fenders OR
  • Pacenti Quasi-Moto knobby tires with no fenders

Fork and Canti Bosses

I’m down to the home stretch on this frame and expect to be riding it in a couple of days (unpainted of course…that will come after some shakedown miles).

On Friday I built a fork using my new fork fixture:

It has 60mm of offset, which will give my bike a trail figure of 38mm when running 38mm wide tires. I used Alistair’s bender to bend the blades and think that the resulting curve is very nice:

The crown is a Pacenti Paris-Brest fork crown. I like the twin plate open look and it didn’t require much cleanup work. The brazing went pretty well, I got it a little hot around the tangs (you can see that in the burnt flux), but did well everywhere else:

I like to have a threaded boss under the crown for easier direct mounting of the fender. I made a tab which fit into the bottom of the steerer on the lathe, then drilled and countersunk it for awater bottleboss. This doesn’t stick out much at all from the crown and it provides a very secure connection.

I built a new canti jig using a short piece of 80/20 (1010 extrusion), the dummy axle holder from my fork jig, and stanchion block (part #5860). The big silver piece started as 120mm of 1″ diameter stainless steel. I machined in two grooves that are 7/8″ wide to center it in the stanchion block and milled flats (3/8″ thick) where the canti bosses are held. The holes are 80mm apart (perfect for all modern cantis) and hold the bosses while I braze them.

There isn’t much left to do on the bike. I need to sort out the cable routing to the rear hub and add some brazeons to the fork to hold headlight wiring. I expect to have it on the road by Thursday this week.

Rack building still goes on in my basement too. Rory came over yesterday and made this cool porteur rack that bolts onto his Vanilla’s pannier/handlebar rack. Click the photo for more:

Frame progress — finished up the rear triangle

I had planned on doing this in 2 or 3 blog entries, but I’m running behind. That means you get one mega entry.

The frame is pretty much done. It just needs cable routing brazeons and rear canti posts. This is what it looks like in profile:

A set of photos for making the seatstays (mostly the caps). Ifound this to be more challenging than I expected. Things that I learned for the next time are to cut the seatstay a little shorter than I did, and make the cap longer. I also should have used thicker caps, I used .4mm thick tubing. That didn’t leave me a lot of room for error. At the end of the series you’ll see a pool of brass on top of the cap, that was to thicken it up a bit.

I made an M5 seatpost binder on the lathe and made this cantilever brake cable hanger too. I like the twin wire design, but enhanced it a bit by wrapping the wire around the seatpost binder. It is very strong, but light and delicate looking.

I was a little worried about tire clearance when I wrote my last blog entry. In response I made a tool for denting the chainstays and went at them. The dents aren’t too elegant, but they gave me a couple of extra mm of clearance and that was all that I needed.

I want a good fenderline on this bike, so I carefully measured tire height with three different tires and a test wheel. I set the bridge 18mm above the tread of the tire that I expect to use with fenders. That still left me pretty good clearance with a knobby (for riding without fenders). The fixture holding the bridge in place is called a “bridge jack”. There was a blurry photo of one in the Patarek manual and I couldn’t find one anywhere else, so I just made what I thought would work. I can adjust it’s length then lock it into place. It worked well for getting the chainstay and seatstay bridges equidistant.

Markings for Quasi-Moto (Q),Hetre,and Trimline tires.  The very top line is where the bridge will go.

Clearance with the Quasi-Moto is a little tight for a mountain bike, but decent.

This bike is being designed for a Rohloff internal hub. The Rohloff has three different options for a reaction arm to keep the hub from rotating. Lee Williams described how R&E used the OEM2 one (normally designed for disk brakes) with a hidden bolt inside the seatstay. My seatstays are very thin, so I added this bridge instead. I like how it looks, it is a lot more elegant than the normal Rohloff reaction arm (photo from an old bike at the bottom). The boss for the bolt head was made on the lathe. It is like a blind water bottle boss, but sized for an M6 bolt. The boss goes all the way through the bridge for extra strength.

The ugly black arm with holes is the normal alternative. I’d say that mysolution looks nicer.

A detail shot of how the eccentric works. I think that this is a little nicer than the normally fully slotted bottom bracket, and much nicer than using set screws:

A couple of blog entries ago I talked about alignment. Brandon Ives saw my photos and suggested making this tool instead of using a square. I call it a vertical dummy axle, and have to agree with him that it works well. The dummy axle just threads into the base. Right now I just have a dummy axle that is 10mm for rear dropouts, but when I make my fork I’ll also make a 9mm dummy axle for front dropouts.