First: the challenge. Cycle Oregon announced its route last week. The 30th. Every 5 years, the course is a big one. Crater Lake is often featured. 5 years ago, we climbed to the Crater Lake rim fomr the south, then the option to go around. I looked at the course when it was announced, signed up, then started thinking that the fix gear TiCycles had just delivered could do it! Huge grade changes but each day, except Crater Lake, was basically one or two very long climbs withthe descending late. Makes for not many stop ans flip wheels ans only one cog change per day. Crater Lake I could go around with just a 23 and a 12. For 23 miles, there are no flat stretches.
This year's course is to Crater Lake again, from the north. Very similar course profiles. Jessica, the ti fix gear, would be perfect EXCEPT - there are three days with 15 mile grave options. A couple of long climbs and a very real multi-thousand foot descent. No way I'm doing those on 25c tires and a 54" (42-23) low just doesn't cut it. I'll be 64 years old for crying out loud.
Then my brain dis what it loves to do. It found a way to ride the course fixed AND stretch the ratios. Ride the Mooney. It can handle 35c ties easily. Put them on for the three gravel days. Ride 27c Opens the rest. Bike has horizontal drops which I spec'd 39 years ago so it COULD be ridden fixed. Now's its chance.
I have heard of using two chainrings and chainlines to get two very different gears on the same chain and with short dropouts. (Mine is the classic and in the 70s very common Campy, not the long version.) But two gears? What two gears does a 60 yo pick to go up 8% gravel, down 10 miles of 5% plus and 20 miles of flat? Fixed.
What about using a "dingle", two cogs fused together and screwed on like a single, on one side and a little descender on the other. Three chainrings. Googled the cogs. Surly makes them but they are 3/32" and Surly recommends a 9-speed chain. 9-speed? No thanks. I want 1/8" track sprinter strength and reliability. This body has seen its share of crashes, including a few from gear failures. I want stuff that is stamped, approved and certified by the Department of Redundancy Department. 1/8" drive all the way.
So, how to make an 1/8" dingle". And that 1/8" triple crankset. Can I get the chainlines to work? And what cogs and rings would I need and is it possible?
Last question first. Actually not hard. Yes, very possible. 45-32-38 or 36 allows me to go 45-13 (93"), 42-16 (71"), 38-20 (51" or 36-22 ((44") with room to push all the cogs one tooth in either direction. So I could set up a 17-21 dingle and put the 12 on the other side.
The dingle. I spent hours at my desk, cogs in hand, wheel at my side with calipers and my AUTOCad open. I saw that the large cog could be put on backwards, ie the outside, flat surface seated against the hub. Cog sits right up on the spokes, but does seat properly. Should work fine. Chain is well clear. The smaller cog would have to be machined out as it needs ot fit over the threaded base of the large cog, now extending outboard. I drew up a bolted version with a machined spacer between and showed it to Dave Levy. He didn't like it but thought that the cogs could be brazed together with a steel spacer, that probably a low temperature silver solder could be found that would keep the cogs below their heat treat temp. (There's a reason I go to Dave when I am dealing with metals!) That would make for a very clean assembly and plenty of room for the cog wrench. (Bolted and nutted with nuts I would trust to 4 times a chainring bolt's load would mean that I would also need a FW style remover tool and a big wrench, not
my 16 ox aluminum chain whip that works so well.)
I'm not there yet on the crankset, but my thinking is that an older Sugino 130 BCD double with its nice straight low Q arms would be perfect. Phil Wood BB so I can dial in the chainline to be as far inboard as possible. Good thing is that I don't actually need clearance. Bike is due for re-paint, so any damage I go this year doesn't matter. And 531 is hardly going to care about some aluminum teeth. I measured a crank spider bolt hole yesterday. 10mm. I should be able to find a 10mm shoulder bolt. Pan head or flat head (would need a touch of machining to the inside rings if I go that approach - I'll have to see about chainstay clearance) and the nut to the ouside. Not pretty but should be bulletproof, even with a TA erector set style assembly of the bolt going through inner chainring, spacer, middle, spider and outer.
I think I can get chainlined below 6 mm off and if I can get the rings far enough in, maybe less than 3mm. The high gear will be the worst. I'll probably buy some aluminum round barstock, drill it down the center for the axle, then just cut spacers as required for the hub on the table saw.
Another plus of this crazy venture - Pete needs attention. (Pete, my Peter Mooney. "Pete' and "Peter" is just coincidence. I had never known a "Pete" despite having brother,uncle and framebuilder named Peter. All to my knowledge did not like to be called Pete. The bike is "Pete" simple because I was riding one day, year three, and just realized out of th e blue, the bike's name was Pete. It didn't come from me. (Funny, I had a discussion yesterday about cats. Was told that we do not name cats. We call them names until we find one that works for the cat and it responds. When I have named bikes, I always end up forgetting what I named it. Pete stuck. It will be formalized on the next paint job.)
So this crazy venture is in real part about falling in live with that old bike again. It has suffered from being a true all-arounder. It isn't great at anything. Anything except being the one bike I could ride anywhere I was going to live 12 months of the year anytime I needed to ride to stay sane over the years after my head injury. For that it was superb and for that I will be forever grateful. And now? How many bikes out there can ride very hilly gravel roads fixed in style? And I could even go crazier and throw panniers on it and tour in that mode! It carries load very well. (Jessica is my pre-derailleur TDF - but post paved roads - racer. Pete is my 19th century tourer.)
My Raleigh Competition could do this except it has one huge barrier - a low BB. It's a pedal scraper. Wonderful a lot of the time, but scary as a fix gear and it will never do that. The Mooney has a 10 3/4" BB height with small tires. Very suitable for 175s fixed. Barely lower than Jessica and more than my winter fix gear.
This also gives me a physical challenge. I need that. (And maybe, just maybe, get me into shape to ride a climb with Suzy Jones, my sister mountain goat. We did a magic 15 miles of climbing together out of Ashland 5 years ago when we were both completely spent, day 4 of consecutive huge days of climbing. Saw her for the first time since last Sept but wasn't remotely fit enough to stay with her.)
This could be fun!
Now off to rebuild my Sachs 7-speed. New chain skips on almost all the cogs. Picked up three used 8-speed yesterday. In the future, Pete is going 130 so they may see use and I am betting I have some usable cogs in the meantime. And I just bought and rebuilt some Power shifters just like I set it up with originally. What great shifters! What great shifting. So I am off. I'll report back as the 3X3 takes place.