This is my new lightweight urban commuter (a.k.a. MARTA bike). I purchased a used carbon fiber frame, and a used mountain bike frame that had been made into a single speed road bike and combined all the parts (plus a few extra) into a lightweight single speed bike. The frame is designed for road tires, and the clearance is very tight, so I am limited to a thin road tire on the back.
The mountain bike frame came with a standard MTB crankset, and I’m using the middle gear (34 teeth) to a 16 tooth rear cog (4.3 gain ratio). This combination makes it easy to get to the MARTA station without too much effort (don’t want to arrive at work all sweaty). I have also experimented with using the larger (42 tooth) sprocket and a 15 tooth rear cog for a 5.7 gain ratio, but that combination only works in the winter when overheating isn’t an issue. Because it’s a commuter bike, I added a LED headlight (held on with a hose clamp) and a detachable RavX Super Sight bicycle taillight. The running weight is 18.6 lbs, or 21.2 lbs when I carry a U-Lock.
Vitus Plus Carbone (Carbon Fiber frame) 55cm 21.6″ (1988)
Vitus Dural 979 aluminum fork, Cinteli Stem, 26.4 Cinelli Bars
Front Wheel: Ritchey HB 575 Rim (26×1.0 tire)
Rear Wheel: Ritchey Hub ZER system, AERO OCR wheel 6061 T-6 Alloy
ETRTO: 622-14, Tire: Vlittoria Zalfiro 25-622 700x25c
Shimano Ultegra 6600 brake on back, “Schwin Approved” calipers on front, Tektro Reverse Alloy TT Brake Levers
Shimano Bottom Bracket, Square Taper 68mmx118mm UN54
RavX Rear Flasher, Front LED light