SF Cyclotouring

Ride reports and other ramblings from a San Francisco cyclist.


2011-12-18 - Marin Headlands Bonty Loop

GGBGGBGGBGGBOld Springs Trail #8Old Springs Trail #8
Old Springs Trail #7Old Springs Trail #6Old Springs Trail #5Old Springs Trail #4Old Springs Trail #3Old Springs Trail #2
Old Springs TrailRodeo Cove #2Rodeo CoveDarkerToy CameraMonochrome

Photos from yesterday's ride...

Via Flickr:
Rode the Bonty RL with new Kona P-2 rigid fork on a Marin Headlands loop. 1:30pm to 5:30pm or so -- around 4 hours total. Rode across the GGB, up Conzelman, down Coastal, up Miwok, Old Springs Trail, down to Tennessee Valley, then back up Marincello, connect to Bobcat, to Rodeo Valley, back up Coastal, down Conzelman, back across the GGB, and back home. I'm guessing about 35-40 miles total. Bike worked fairly well. New handlebars are good in terms of reach and height, but are too wide. Rear shifting is still wonky in the large chainring. Bike still shimmies, even with the new fork, too.


2011.12.10 -- 1993 Bridgestone RB-1/7

Mostly StockIMG_0420.JPGIMG_0422.JPG105 rear hub, Ultegra 600 derailleurSalsa stem, Nitto Dream barRims
Ultegra 600 CrankOriginal chainringsUltegra 600 Front DerailleurIshiwata Extreme CRMO"BRIDGESTONE"Ishiwata Croston O22E
172.5 cranksPaintThat DecalThat Decal"FABRICATION JAPON"Teeth

Via Flickr:
Pulled this one down off the wall to take a closer look. It's been awhile!

Fender Repair

Fender Repair by jimgskoop
Fender Repair, a photo by jimgskoop on Flickr.

Via Flickr:
Snagged a stick or something on my commute home last night, which tore off the back half of my front fender. (FWIW, the SKS strut safety releases did their job!) Fortunately, I had a spare set of SKS P-45s stashed away, so replacing the front was fairly easy. I cut a good section out of the trashed fender and added it onto the front of the replacement to lengthen it under the rack. I'm not happy with the zip-tie attachment onto the rack, but I was running out of time last night, and it was all I could come up with. I should've added a threaded fender mount under the rack platform's crossmember when I built it....



Recently I measured my Kogswell 59x700C P/R's fork -- the one designed for 40mm trail on this frame. It's 400mm axle to crown, give or take:

Kogswell Fork

The blueprint says this fork should be 365mm, which is impractically short for a 700C-wheel frame. (?!?!?)

Kogswell 700C P/R Blueprint

I also just got a Wixey digital angle gauge, and used that to measure all the
angles on my 59x700C P/R frame. They all vary pretty far from the as-designed values. My bike has a head angle around 71.5-72º, which is supposed to be 73.6º.

Kogswell Head Tube Angle

The seat angle measures 70.6º vs. the specified value of 72.4º.

Kogswell Seat Tube Angle

Finally, as you can see on the blueprint above, the BB drop is supposed to be 79mm, while the actual value measures to around 70mm.

This makes me wonder if, overall, the fork was manufactured too long. If it was 20mm shorter, it'd be closer to the blueprint, and both of the frame angles would be a full degree steeper (10mm of fork change makes the head angle about half a degree steeper). FWIW, there ARE about 20mm of spacers between the fork crown and the front fender, indicating that the fork is longer than it needs to be.

Kogswell Fork Crown Fender Spacers

Using these actual values plugged into my trail calculator gives a trail of 54mm and flop of 16mm. So the bike is not even low trail after all! :(