Archive for the ‘Ivy-T’ Category.

Ivy-T stem

This is the first stem that I’ve built.  I did this one jigless, just counting on accurate miters to hold everything in place.  That worked pretty well, except that my front clamp was about 1mm off center (fixed that with a file, but that made it slightly narrower than I wanted.

Some details:

  • 1″ x 0.058″ extension (9cm long), 1.125″ x 0.058″ spacer, 1.125 x 0.051″ clamp.  I’d prefer to have more material on the clamp in the future, and may buy some thick wall 1.25″ stock to turn down.
  • roughly 95 degree angle (not measured precisely because it doesn’t really matter)
  • roughly 9cm long (same reason)
  • integrated cable hanger and spacers
  • non-stainless bolts for strength
  • the cable hanger fully pierces the top and bottom of the stem

double miter for the clamp and front

Checking the miters. Not done yet, there is too much of a gap under the handlebar clamp.

Brazed up. No burnt flux here!

I haven’t fillet brazed in quite a while, and was very happy with how these joints came out.   They didn’t require too much cleanup.

Ivy-T progress


The most important bit of progress is that the bike is rideable, and I’ve been commuting on it for a week.  It isn’t done, it needs a front rack, stem, and tail light (all will be custom), but rideable is a huge step.

It is a nice compliment to Gifford, pretty much the only bike that I’ve been riding for a year.  Gifford is utilitarian, the station wagon of a bicycle fleet.  The Ivy-T is much sportier, currently weighing in around 23# with fenders, battery powered lights, and a frame fit pump.  If I can keep it near 23# with generator lighting and the front rack I’ll be very happy.

Ivy-T in rideable, but not yet finished, form

The Diacompe GC450 centerpull brakes work very well. They almost never squeal, do a fine job of stopping, and are light and nice looking. I'm surprised, but the 27 year old brake pads (never used) even work well.

Brandon Ives did a nice job brazing the lugs (with silver). My fork crown, done in brass, is a little messier.

Here are some photos showing some of the fork building steps.  I don’t have a photograph of the fork raking because I raked these fork blades months ago at Alistair Spence’s shop.  I don’t have a fork bending form yet.

First the crown was brazed to the steerer. This is done first so that I can turn the crown race down on my lathe (easier without the fork legs attached).

I remove the flux and clean up the crown by hand. The aluminum rod sticking out is a part of the fender mount, and works with an eye bolt to keep the fender in place. It will be cut trim at installation time.

Dropouts are brazed in and cleaned up. I made these dropouts myself on the CNC mill.

I use this fixture to check the frame angles and set the fork blade length. The fork blades are uncut and the front axle height is setup until the angles are correct. The difference between the front and rear axle height (142mm front, 150mm rear) tells me how much fork blade to remove (8mm in this case).

The fork blades are not yet brazed during this operation. A dummy headset (made by Alistair Spence) is in place.

seat tube angle

head tube angle

The fork and trimmed down blades are set into the fork fixture for brazing. This is my second generation fork fixture, I'm going to sell these as a kit later this winter.

The blades are brazed into the fork crown.

The flux is soaked off in hot water and everything is cleaned up. The top hole on the inside of the fork crown is open as a vent hole and will be used to run the wire for the front light.

The fork alignment is checked on my alignment table. I had to tweak one fork blade slightly. Rake was left at 63mm.

Finally, here is a photo of the fender mount in use.  I learned about this setup from Jan Heine.  The fork crown is drilled in the back, and there is a blind hole in the front.   A piece of aluminum rod (fender stay) is put into place.  The tension of the fender’s eyebolt holds it in place.  It looks very clean, it is light, and it was easier than making a threaded fitting in the bottom of the fork crown.

Starting on the Ivy-T

Seattle’s rainy fall started today, which can only mean one thing: time for me to build a bike.  In the last year I’ve ridden all but about 200 miles on my new bike Gifford.  I like having a slim stable, but I also kind of miss having a second bike.

A few months ago I posted about getting this frame from Brandon Ives of IvyCycles.  The frame came to me with most of the hard work done (the front and rear triangles were done) and ready for all of the detail work.  I love the detail work, so this is a great partnership.  The brazing that he did looks great, hopefully I can keep a high standard on my part of the bike.

I call this bike the Ivy-T because it is heavily inspired by one of my favorite mass produced bikes, the Bridgestone RB-T, but built by IvyCycles.  The frame geometry is more or less a copy, just resized slightly to fit me better.  We used lighter tubing and better lugs that the original, but it is still Ishiwata tubing (this bike has 019 (8/5/8), the original used 022 (9/6/9)).  I still need to build the fork, but the bike will get a low trail fork that looks similar to the ones on my other bikes.  I’m going to use this fork crown:

Mitsugi Crown from Kirk Pacenti ( The link takes you to the stainless version, but I'm using the normal steel one.

In the spring I was lucky enough to find a set of Dia Compe Grand Compe 450 centerpull brakes.  They came complete with braze-on studs, and had never been installed!  I’d been wanting a set of these brakes since first seeing them on a bike that Mitch Pryor (MAP Bicycles) brought to the 2009 Oregon Handmade Bicycle Show.  Centerpulls never really got my attention before, but I love the way these look.  They are a nice mix of refined and mechanical at the same time.  I watched eBay for a while and never saw any go by, but then these ones showed up on the BOB list.  I jumped on them.  Mitch was very helpful and emailed me original documentation for these which showed where the studs should be installed (the critical dimension is 62mm between the studs, although anything between 62mm and 65mm looks good to me).

Over the last week I made some curved bridges for the frame and brazed on the studs for the rear brake.  Here is are the photos from that process. 

I made this 3" radius bender using a circle cutting jig for the router and some scrap plywood. It was made in two halves with a chamfering bit.

This is what the bender looks like when assembled. To use it I just clamped it into my vise, trapping the end of my 3/8" tubing underneath. I pulled the other part around by hand.

I made this simple jig for holding the studs in place. I took this photo after tacking the studs, I wanted to check alignment before finishing the brazing.

I took this photo just after putting the torch down, but before removing the flux.

The flux has been soaked off. I'm pretty happy with how this brazing looks, I'm really out of practice. You can also see the curved bridge here.

Tons of clearance under these very pretty brakes. They are listed as 55mm reach, but I've never seen a 57mm reach dual pivot with this kind of clearance. The curved bridge hides nicely behind the brake arches.

I was really worried about having the gap between the brake arms be consistent and small. A little misalignment of the studs is barely noticable with cantilevers, but could cause big problems or look terrible with a centerpull.

One final shot of the installation, where you can see how the springs work.

Before installing the bridges I indented the chainstays slightly for increased tire clearance.  I hadn’t planned on doing this originally, but the brakes fit larger tires than I expected (my 38mm wide studded tires fit), and the chainstays were the limiting factor on tire clearance.  These photos are for JimG, who has asked me in the past for photos of my chainstay indenter.

I intend the chainstays on my 3" vise. Sometimes a skinny vise is useful!

Post indention, before bridge installation.

This is what the indenting form looks like. I made it from 5/8" rod, filled down to a reasonably nice shape, and brazed to a small piece of angle iron.