Wednesday, October 12, 2011

Techie Tuesday: Single Speed Conversion

I've been a bit at a loss at to what to do with my old friend, the Nishiki Competition I bought while attending UC Berkeley in the spring of 1980 at the Missing Link (the shop is still open btw, and being run as a Co-Op) I have so many wonderful memories attached to this bike, but without downtube braze-ons for shifters, nor water bottle bosses, bringing it up to modern bike standards is difficult, and, seems somewhat unnatural. Better to have it a vintage bike with vintage equipment.

Me & Tea & Nishiki, halfway up Monitor Pass, circa 1982
After following a single speed bike from the Aquatic Center up to Folsom, and hanging onto his wheel with considerable effort, we had a very productive conversation about what his conversion entailed. All of those missing frame bits my bike doesn't have, he had to cut off, and mine does have the all-important horizontal rear dropouts, so important for adjusting chain tension.
Nice, clean look. SunTour Supurbee brakes are an exact Campy copy circa 1985. Cleaned, treated with Naval Jelly to arrest rust, and all steel parts treated in hard parifin wax and Canola oil at ~ 400 for 20 minutes. Bontrager brake pads were the only ones that fit.
Excess Technologies California freewheel, SunTour horizontal dropouts, and donor mtb skewer with toothy surface to keep the axle planted under load
Ofmega sealed bearing hubs by Campy, circa 1985, Wipperman 3/32nds stainless chain, and perfectly straight chainline between 120mm dropouts. The latter makes replacement skewers hard to come by.
Pristine Campy 52T big ring, turned inside-out and moved to the inside postion on the Sugino SuperMighty 135 BCD, 5-bolt crank. Very rare SPD aero racing pedals.
Big ring clearance is only ~ 4mm. Tight, but makes for a wonderfully tight chainline.
Just love the clean look, and tight chainline. Still have all the original decals intact

Zip ties covered with vinyl tubing do a great job holding the bottle cage in place with the help of a strip of sticky rubber from a tail light mounting kit.
Street legal with cage and borrowed saddle bag. Just love the very clean, track bike lines on this. Handbuilt, 36 spoke wheels feature Mavic rims and Ofmega hubs. Campy BB, Omas alloy headset, and Laprade seatpost. Rear brake cable housing clamped to toptube using vinyl-coated zip ties.
 Last week it was raining, and a perfect opportunity to pull the trigger on a SS conversion, so after mulling it over for days, I got out the wrenches just after midnight, and stripped all the gearing off, sans the 6-speed Regina freewheel, which I didn't have the tool for.

The next day I went to MadCat on Marconi, and had them pull the freewheel off, check the sealed bearings on the Ofmega hubs (made by Campy in 1985), and mount an Excess Technologies California 19T freewheel. The bearings were in perfect condition, and I chose the freewheel because it felt smooth, and was chromed head-to-toe on the outside - important for a foul weather bike.

Carmichael Cycles had the special shorter crank arm bolts needed for running just 1 chainring, took the 42T inner ring off, moved the pristine 52T Campy big ring inside, and flipped the face to the inside to match the stub bolts. The crank is a Sugino SuperMighty, an exact replica of a Campy Record crank of the same vintage, and has 135 BCD rings, as expected. If the 52T hadn't been so pristine, and if Campy 135 BCD weren't so expensive, I probably would have gone with the usual 46T or 48T front ring.

As Sheldon Brown's site mentions, moving a full-sized big-ring to the inside position isn't always possible, because the chainring will often hit the chainstay. In my case I have about 4mm of clearance, and that is very close, but enough. It's important to keep in mind that static clearance isn't the litmus test. Go mash up some hills and make sure the frame flex isn't going to allow the chainring to rub.

You'll also need to extract, or cut the crank arm chain block pin off of the chainring, as it will be turned towards the frame once flipped around. In my case, turning it round and round with a small ViceGrips did the trick nicely, but I was a bit disappointed that the beautiful Campagnolo stamp on the face of the ring ended up turned in, and is now only visible from the "ugly" side of the bike.

With the crank all set up, and the rear wheel adorned with the new freewheel, I moved the micro-adjusters all the way back in the rear dropouts and started cutting chain. Without a derailleur you have to get the chain length almost perfect, and 19/52 is a little hard to fit to my bike's chainstay length. I cut the chain a half-dozen times, and ended up with kind of a half-link by using the Wipperman quick link to bridge between 2 male ends.

The Wipperman chain is 3/32", and once I settle on the gearing, I'm going to switch to a Wipperman Inox 1/8" chain. It's stronger, new, and the extra width should allow sand and grit to fall off the drivetrain, extending its life.

I used vinyl tubing encased zip ties to lash a waterbottle onto the downtube, and pulled the saddle bag off my Roubaix, and headed out the door for a short 15 mile ride. There are a lot of roller between me and the ARPT, some with grades of 7-8%. Coming back from WBP though, there is one short hill that is just over 9% grade. I was worried about that, and found a longer, flatter route just in case. I'd ridden the detour in 52/16 gearing, so knew I had a good out if I needed it.

The ride to the ARPT was a lot of fun. I worked a little harder, but loved the sound of the freewheel whirring away on the downhills, and got a good glute workout, standing and mashing up hills. The 57cm frame has a lot more cockpit room than my 54cm Roubaix, and that is definitely helpful when climbing out of the saddle.

Once on the bike trail I started ramping up the spin. Nothing intentional, it just happened, and soon I was spinning close to 90 rpms. Next thing I knew I was into a headwind, and down in the drops to shed some wind. Nice! The 52/19 was just perfect for the climb over the WBP bridge, and after pulling my bottle and taking a long draw of GatorAid I felt strong heading home.

Approaching the decision point, I decided to turn right and try mashing up Sara Court's 9% grade. With fresh legs under me if I couldn't do it now, I sure wouldn't be able to do it when tired. I got a little run at it and just managed to mash up to the top, impressed at how stiff the frame was. Stiffer than I remembered it being.

Coming home on California, with its badly broken and mangled surface, I was also surprised that the fork soaked up bumps so well - better than my carbon bike I think. I must be due entirely to the extra weight, as that fully-sloping crown is very stiff.

I have ordered a freewheel removal tool and a 17T freewheel, bought a new bottle cage, and need to repack and tighten the bottom bracket, but all in all, this was an easy conversion. I am looking at fenders and moving the Roubaix's pedals over, so still a few details to attend to, but this really makes the most of this bike. It's clean frame, horizontal dropouts, and low end Tange 4130 CroMo tubing just make this conversion feel so right. Riding this bike again is just pure joy. So many memories we've shared together ride with us.

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