This bike has been in the making for awhile because it took me awhile to research all the different aspects of the build. Many firsts for me – Alfine and a Gates Centertrack belt-drive being the main ones that added some complexity to the frame. Jack wanted the ultimate commuter for getting to work in Portland and also for bike tours out to the coast and back on dirt roads with panniers front and rear. He wanted this to be a disc bike with clearance for 40mm gravel tires (Clement X’Plor MSO’s or WTB Nanos) as well as full fenders because he’s in Portland. Internal full length housing in the front triangle. He will using an Alfine 11 and putting a 46t x 24t, maybe going to a 22 in the back. Disc lugged crown fork with eyelets for the Tubus Duo low-mount rack and fenders.
After a question to Gates regarding ‘best practices’ and what they recommend for dimpling vs. brazed-on cap, reading and re-reading their great manuals and website, I had the right chainline (beltline) and ring clearance. The belt-line is very narrow on the Alfine making it hard to fit without a big dimple on the outside of the chainstay – especially when you want also to fit wide tires and fenders. I chose a chainstay length of 443.5mm with a belt of 115t to accommodate all of it with this gear ratio.
The tubeset is a mix. True Temper OX Plat front triangle except for the tapered 34/44 head tube in case he wants to swap to a tapered steerer fork, 68mm BB shell, 4130 5/8″ x 0.028″ seaststays bent by me and a Paragon tube splitter brazed in, Dedacaai s-bend chainstays of the cross version with a strategically placed cut-out cap for belt-ring clearance. Paragon hooded sliders of the black ano post-mount variety. Pretty standard touring geometry but adapted for flat bars so a longer top tube than I’d use if it was for drop bars. It has 74mm drop (10.8″ high with 40’s), 72/72 angles + 48mm fork offset = 60mm trail. Jack’s a pretty tall dude so it’s a 59 in the seat tube and 63 in the top, 661 front center.
Mitering for the tapered head tube was interesting but not as difficult as I expected. I started the miter on the horizontal mill with a 1.5″ diameter hole saw, then used the BikeCAD miter template to wrap around and filed the rest from there. File to fit didn’t take super long and voila! The other interesting part of the build was the chainstay cut-out. I loaded the chainstay in an Anvil chainstay mitering fixture tube block to keep in phase, then clamped that in the mill vise, coped with a hole saw and brazed a piece of 1.25mm walled head tube in there. Gates said they’ve seen more belt-drive bikes fail with dimples than caps so…i chose a cap.