Cyclocross Single Ring Set-Up
I've a had a boat load of folks over the last two weeks or so ask me various questions about the single ring set up I have been using for years. Well, roughly since 2002, anyways. I think the most important question, however is why? At first, I ran it because Bart Wellens ran it when he was winning WK's for Spaar Select, so OF COURSE I had to run it! But in all seriousness, I wanted something reliable, always shifted (or more accurately...didn't have to WORRY about shifting the front) and would basically help ensure I could keep going on lap after lap when I had no pit support back in the day.
My initial experiences racing in CA in torrential mud on certain courses (remember El Nino, CA 'crossers in like '98??) taught me quickly that trying to get from the 46 to the 39 was a challenge and I would find myself looking down WAY too much and stressing about not being able to shift. Forget about going back to the 46! So I just dumped the two ring thing and never looked back.
So, for the last 6 years or so, it's been a 42t x 12-25 or 12-27. Personally, I've found that I've never missed anything (e.g. gear-inches) by not having the 46. I could see how it's needed on Euro courses where they've turned into grass crits. But here, the courses are still technical and I think tuned perfectly for a singe ring. In my case, I am running 175 SRAM Red cranks (130bct) with FSA carbon guards. The 42t FSA ring is mounted on what would be the 'big ring' side of the crank, utilizing extra long crank bolts (you can find them at most good MTB shops.) The rest can be explained in pictures...
I have roughly 3-4mm of clearance here. I had my frame builder, Paul Sadoff of Rock Lobster allow for this application and he has some phenomenal techniques to bend in the chain stays while keeping them super strong.
The chainline is as you see it. In the 25 or 27, the chain does not rub the guard and has roughly 1mm clearance.
A shot of the chain stay and guards.
Saturday, September 20, 2008 at 1:31PM
Reader Comments (8)
Hey Greg.
Seems that there are no space between the internal chainring & the chain when you're on 42*27 ?
http://1.bp.blogspot.com/_nhTxq79ZguM/SNVRKU4UtHI/AAAAAAAAC6A/J9IX7NlBcEc/s1600-h/IMG_2873.JPG
Howdy Greg. I wrote something last month on single ring setup, too:
http://www.erikv.com/blog/index.cfm/2008/9/6/Single-Chainring-Cyclocross
How do those carbon guards hold up to hits? I smacked one of my metal Salsa guards last year on a tree barrier and it got a little dent. I figure if it was carbon, it'd of munched pretty good, maybe enough to have to limp to the pits.
Single ring setup is for sure the way to go!
wow i sure could have used that summary of your setup a few weeks ago! I've been research it on my own since seeing your gearing at one of the clinics.
I didn't realize it when i first started riding it but the 2001 major jake i've been riding has a massive 48-38 that i've been training mostly in the 48 on. no wonder i've been getting sore knees! anyway, reading up on roadbikereview.com i found excel sports here in boulder sells a kit that will convert most doubles into a single with a chainguard, single ring and a 3rd eye chain watcher.
i went with the 42cm ring and seems to be riding great so far. i've dropped a few times and gotten it stuck below the 3rd eye so I'm still tweaking that but the chainline seemed dead on from the get go.
Thanks for the insight Greg, I was one of the "boatload" of people that asked about the set up. I did find it funny the day after you wrote back to me that Matt Pacocha, who you said you were going to talk to about the very same thing wrote about single rings in Velonews. Thanks and good luck in Vegas!
Kevin Kiddle
erikv,
Been using the carbon guards for several years now (4?), just this past year had one finally croak -- hopping a curb to avoid a car this past summer, not cross related at all... Got a good crack in it, and it came apart really quick afterwards... Otherwise (ie, in actual training and racing) no complaints at all...Some dents on the outside, so it doesn't look so pretty after a while, and can get some splinters around the edge, but no major disruptions otherwise...
FYI: FSA Carbon guards...
-Lane
First, SORRY for the abysmal spelling! I jammed out teh post before trying to head out to a wedding.
Clement:
That is a weird angle. The chain "appears" to be hitting the chain guide but in reality it is much lower than the guide as that is where the guide's circle starts to drop.
Jasper:
Dude, 48 is monster man. Way too big for cross IMHO. You'd rarely get to use that for it's true purpose...dirt road riding!
wow, i'm happily suprised that the chainline looks so good. i'm about to set up a new bike with DA10 cranks/bb and was worried that the ring in the outer position would be too far outboard.
what's with the unused cable guide underneath the bb?
I had really good luck for two years running a 44 single ring setup bolted directly onto the spiders of a standard Ultegra crank. (Not coincidentally making it an easy conversion to roll fixed/single, it worked fine where the chainline was straight for the fixed wheel - gotta love SRAM master linked chains for the quick change.) The bike is a Crosscheck, 105 der, with 12-25 or 12-27. Dropping chain now and then was an issue, and rather than go with double chainguards on long bolts - a somewhat heavy option - I ran it last year with an old bolt-on derailer, not wired but just bolted onto the seat tube. Not a smooove looking setup, but utterly functional, light, and cheap. Voila - no chain drops. On a double on the new bike this year and the 46 is real useful so far, more than I would have thought.