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 (bikelugs.com). 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.

19 Comments

  1. Alex Wetmore says:

    The canti fixture was copied from this one:
    http://www.flickr.com/photos/shortpants51/3385974098/

    Nice idea, and trivial to make!

  2. Fred Blasdel says:

    Holy shit Alex, seriously? You”re doing god’’s work.

    I”ve lusted after those brakes for a long time. A while ago there was a guy selling an original advertising poster on eBay and I was tempted to buy even just that. Somewhere in one of my piles I have a set of the matching levers I got accidentally, though the hoods are dried out and the levers are scuffed up (the worst part is that the logo is rubbing off as it wasn”t pantographed like on the brakes).

    Do yours still have bearings in the pivots when mounted to brazeons instead of a hanger bridge? Are they ball bearings or roller bearings?

    Were the pivots OEM or bespoke? They look a lot like Amir Avitzur’’s work — he’’s been making them them for Mafacs for a while, and has some insane projects in the pipeline like reproductions of Prior hubs and Simplex skewers.

    IMHO the only other centerpull in the same league were the CLB models, which had a similarly spectacular finish and angled pivots for a self-energizing design that avoided toe-in issues. No real way to do that with brazeons though, frustrating the fancies of us nerds. One of the models had no pivot springs and used a solid springy straddle cable instead. Both models also unfortunately used threaded brake pads, making them less adjustable and with arms more flexible in the braking direction.

  3. Brandon Ives says:

    I”m glad it’’s finally coming together. Curved bridges are where it’’s at, they just look classy. Oh, center-pull bakes are really nice and your Gran Compes are excellent examples of the breed.

  4. Alex Wetmore says:

    Fred — They are OEM pivots. I have some of Amir’’s pivots too (originally I was going to use Mafac Racers) and they are very similar, but when compared against each other there are some obvious differences. The biggest is that the OEM pivots are pre-mitered and appear to be cast, while Amir’’s pivots aren”t mitered and are machined. Both use the same style of spring retainer. These brakes also didn”t come with an arch, they just came with the braze-on pivots.

    I”m going to have to make new pad holders for them, these pads use a smaller than normal diameter post and no pads are made for those anymore. Mafac pad holders work, but don”t look nice enough to go with these brakes.

    These GC450s don”t have ball bearing pivots. I believe they made the braze-on brakes with them, but I don”t have them.

  5. Alex Wetmore says:

    I”m glad that it’’s finally coming together too Brandon. I originally hoped to have it on the road before summer, but better late than never! It will make a very nice Christmas present for myself.

  6. Ely says:

    Your braze on jig is really nice. I”m going to try that idea, it looks really simple and solid.
    The bike looks great, the curved bridge is so beautiful. Try showing that to a non-bike geek and explaining it.
    “no really, isn”t it awesome, really, you”re not looking, see how graceful it is?”
    at least, that’’s how my comversations with my wife go…
    The RB-T is a rad bike.
    I”ve had one, then had another bike built to its dimensions with slightly different modifications, including fork offset.
    It is a dream to ride.
    I”m sure yours will be awesome as well and will hopefully fulfill your dreams, until of course, the next dream comes along…
    but that’’s why we have multiple bikes right?

  7. thanks for the post. its funny that you started the story with a fork crown and ended with a brake bridge. looks like its going to be an awesome bike.

  8. Jim G says:

    Alex, thanks for the chainstay dimpler photos! Another great project in the works — can”t wait to see more!

  9. dvancleve says:

    Hey Alex, not that it really matters but what happened to your Ivy bike that got you started down this path? You made Gifford, correct?

  10. Jimmy Livengood says:

    Looks like fun. Is this a 650b or 700c?

    I”m curious what other components the bike ends up with that can keep up to the standards of those beautiful calipers (though the wheel guides seem a bit out of place).

    Jimmy

  11. Alex Wetmore says:

    700c. I considered 650B, but the frame was originally meant for 700C, and these calipers would be a pretty tight fit with 38mm wide 650B wheels. I”m building this bike as a “go-fast” (for me) bike with somewhat lighter parts. I”m hoping that it ends up around 4-5lbs lighter than Gifford, just to make a noticable difference between them.

    The other components don”t live up to the brakes, but are all pretty nice. Ritchey Logic 94mm BCD double cranks with 42/30 chainrings; Shimano XTR M900 derailleurs; Nitto seatpost, stem, and handlebars; Dura-Ace 9sp downtube shifters; Schmidt hub; kind of a normal Alex build. Originally the fenders will just be the Berthoud stainless ones because I have them on hand, but I may swap them out for something aluminum down the line.

    I haven”t figured out what I want to do about the front rack. I think that a small handlebar rack that was chromed would be most fitting for the bike, but a larger porteur rack (basically a clone of the one on my other bike) is actually the most functional for me. I may build both just because I can. There isn”t really a good way for me to visually or physically lighten up the porteur racks much while still leaving them functional…they already come right around a pound.

  12. Alex Wetmore says:

    Yeah, Gifford was the replacement for my Rohloff IvyCycles. I did make a lot of changes from the IvyCycles…things that I now see as important learnings, but which I wasn”t ready to accept in 2006 when I first drew up the IvyCycles plan. I needed to have that bike to learn that 650B really made sense for this application, eccentric bottom brackets were a better solution than sliding dropouts, and that 7/4/7 tubing was too light for loaded touring.

    In comparison I”ve been riding Gifford for almost a year now, and can”t think of anything major that I”d change. I”d make very minor tweaks to the locations of a couple of brazeons, but none that really matter.

    The Rohloff IvyCycles died an untimely death in June or July 2009. I don”t know if you remember, but I had a car/bike accident while riding that bike literally weeks after receiving it (so early on that I didn”t even have the proper fork for it yet). Two years later the downtube failed behind the head tube lug. It looks like there was a crumple there from that original accident that wasn”t noticed during inspection, and that started a crack. One of the reasons that I”m not keen on very light 7/4/7 heat treated tubing anymore is that I think it is probably a little too brittle and fragile for bikes that will take a beating. A car/bike accident is an unusual beating, but I think that the punishment of me riding that bike all over the place on dirt roads with camping gear probably would have done it in at some point anyway. To be fair Brandon warned me of that as soon as I specified that very light tubing.

  13. Christian Berger says:

    Alex, my friend Tom Tunguz just posted this CNC machine that can be built for under $100. Now you can start machining your own components!

    Great blog, I”m not a builder, just enjoy keeping up on your projects and cool bikes.

  14. There’’s the link..

  15. Phil Brown says:

    My canti/centerpull pivot jig is just a piece of flat aluminum bar with a hole and a slot. And I use my drill press pillar for the form when I make curved bridges. And I just use 1/2″ mild steel.
    Phil Brown

  16. David Feldman says:

    Alex, for your brake bridge bending form is the plywood anything especially hard–maple, for instance–or just regular old lumberyard plywood?

  17. Alex Wetmore says:

    It is regular old plywood. It came from a cabinet that we removed from the house. It looks like birch furniture-grade plywood, but I don”t know for sure.

  18. rory says:

    ok, so after reading the latest bicycle quarterly and remembering it was coming out, are you building the fork for the new schmidt wireless hub? i remember you mentioning using Keith’’s dropouts, but i was wondering if the new hub was the reason…

  19. Alex Wetmore says:

    No, I”d like to use the new hub, but I don”t have access to the special dropouts and I already have a good 700C Schmidt wheel built up.

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