If you've followed this blog for a while, you'll know about my somewhat unconventional touring bike: my Co-Motion Pangea.
Click here for the review and photo gallery on The Radavist.
Yup! That's Mine!
What makes it unconventional, yet imminently cool is the Pinion drive, an 18 speed internal gearbox. I selected this option on the custom build because I wanted ALL the best features of a ultra-endurance touring bike, namely high reliability, low maintenance, and the widest range gearing system (636%) of anything available on a diamond frame bike. I enjoy the speed of fast downhills and strong tailwinds (high-gears) but I NEED to be able to climb sickly steep hills with a full touring load (low gears). And, I like having "the perfect gear" everywhere in between. Yeah … weird statement from someone who has twice crossed the USA coast-to-coast on a single speed. That's a whole different story.
So the Pinion drive promises everything I've needed. Except …
The Pinion drive makes use of the Gates Carbon belt rather than a chain. Belt drives have a couple huge advantages over a chain drive system in that they require no lubrication and belts are many, many times more durable and longer lasting than chains. For one thing, they don't "stretch" with wear as chains do. And if belts can power motorcycles and 10,000 HP race cars, I'm sure they will hold up just fine under any load this old man can produce. And so far, that has proven true. With over 7000 miles on the belt to date under often "less than pristine" riding conditions, my belt is running just fine and the belt has far out-lasted any chain I've used and showing little sign of wear. Gates conservatively estimates a life-span of 20,000 kilometers but I've heard stories of them lasting 30,000 MILES!
So, the "Except"?
Chainring. ("Belt"ring, actually) The Gates Carbon belt uses front and rear cogs that match the belt. The preferred design for touring and mountain bikes is the "CDX" type which is an improvement over the urban-oriented "CDN". And now, the CDX line has been improved. When I got my bike, it was set up with the stock CDX ring, made of the 6061 series aluminum alloy. For those of us with machining and materials background, the 6061 series aluminum is a decent structural grade aluminum. We've all seen bike frames and other components advertised as made with this series. But, there's another "number" most of us have seen used in bike applications: "7075". This grade (and I'm not certain why) is often marketed as "aircraft grade". I haven't built any Boeings or Cessna's lately (although I've jumped out of MANY Cessna's, Beech 18's, and DeHavilland Twin Otter's), but I'll agree that 7075 is a far tougher and stronger (and more $$) quality grade than 6061. But that's what I started with. "Stock" stuff.
And after 7000+ miles (much of it off-pavement), this is what my front ring looks like:
Note the scalloped condition of extreme wear on the teeth. Yup … that ring is toast. I've had regular, decent quality CHAINrings FAR outlast that! (OK … maybe except rings on my 1977 vintage, French made, Stronglight 99 crankset … THOSE were a yearly replacement) So, I had to find my options. I mean, who cares how long and economical the belt is if I hammer through rings like I do slices of pizza at c-stores on club rides? So looking into it, I find that Gates already has the solution. Admitting that 6061 series rings are likely OK for "regular" use but not so much for "abrasive" conditions (like, maybe … OFF-pavement?), Gates has released two alternatives. One is a CDX-SL ring made of 7075 aluminum. Cool! A friend who also has a Pinion drive sent me a photo of her CDX-SL ring with 4000+ miles, mostly gravel riding on it.
Far, far better looking than my stock 6061 ring, and major kudos to Co-Motion for building up her bike with the upgraded ring! (I'm unsure if they even existed when they built mine) But looking at her ring very closely, I can see the very slight beginnings of wear on her ring. Not bad, but it is beginning. When I was investigating solutions, I had a look at the entire drive train and noticed something interesting. The REAR ring at the wheel ... made of stainless steel and NOT aluminum ... shows exactly ZERO wear!
It's like it's brand new out of the box. AHA! Wouldn't it be cool if Gates made a FRONT sprocket made of stainless steel?
And I ordered it ... the CDX:EXP. That was an exercise in web searching since my LBS (my preferred way to support my bikes) had no access to Gates rings from it's regular sources, but I learned that Bikeman.com of Woolwich Maine is the USA distributor of Gates Carbon Drive components. (And coincidentally, the dealer for Carver titanium fat bikes as well … Hey, I can dream, right?)
So, the new ring arrived yesterday, and I got it installed and test rode the bike in no time! Sweet! Silky smooth and dead quiet!
Being that it's a special part on a special bike, I needed a couple special tools, again. Yeah ... my bike tool collection continues to fill my machinist's roll-around, riser and top-box, but I've got room. To pull the ring, I needed Pinion's own lock ring tool …
And similar to a chain whip, I needed the Gates strap wrench to hold the ring while unscrewing the lock ring.
Now that I've got ALL the tools to maintain my maintenance-free bike, I wonder if I'll ever need any of them again. I guess I'll just have to ride the crap outta this bike and see what happens. Gee … what a problem!