So, the Tektro R737 calipers arrived, and thankfully quite quickly! Whereas the R539s have a SRAM-like open triangle form (from the arm to the cable stop/barrel adjuster), the R737s have a more traditional single arm/form a la Shimano R650s (and many Shimano brake calipers). The R737's finish is beautiful--not as try-hard super-polish like the R539s--more mature and perfectly matching the Technomic stem, polished seatpost, and (in the future) the Dura-Ace componentry. I think they look perfect on the bike. Tektro advertises their reach as 47-59mm vs. the R539's 47-57mm. Either are more than enough to work with this 720, and I would say the R737's extra few mm's of reach would be very welcome on low(er)-end vintage bikes that came with 27" wheels and the brake pads a little too close to the bottoms of their slots, which would normally make a 700C wheel conversion dicey. Yes, one could go to the long reach R559s, but the pads would be way up at the tops of their slots, and the whole setup would look goofy (IMO).
Due to the 737's design, its "open" position sees the secondary/front caliper arm dip considerably below the mount bolt, thereby removing a good 6-8mm of vertical clearance. In the "closed" or cabled-up position (aka ready to ride), that clearance is gained back, as you will see in photos. This will make fender mounting difficult as I will essentially have to cable up the brake calipers first and then shuffle the fender around etc. It's height over the tire will be affected, and likely give me things to think about when deciding how "open" I want it to be for tire removal. The cart is on the horse here.
Macro photo first. Brake pad positions are obviously not adjusted at all here--just an initial mounting to see where things are.
The profile is nice, especially that front/crossover arm.
You can see the drop in clearance due to the open position of the front/crossover caliper arm. I do like the radiused sculpting for the pad slots. A nice nod to vintage centerpulls (intentional or not).
I'm squeezing the caliper to give a better idea of how they look ready to ride. Very nice.
Rear caliper, low clearance!
Rear caliper in ready to ride mode. Much better!
Front caliper's elevation is more snug than I would like, but it's reality and I'll need to work with it.
Still lower than the rear, but much more workable. I will have my work cut out for me achieving not only a nice fender line per wheel, but also matching front to rear.
