Tuesday, February 9, 2016

Going One-By

1x Builds

Eleven speed cassettes have convinced some that a single front chainring is a realistic choice.  With cassette ranges going as big as 11-36 (road) and even wider for mountain, a single 46, 48, or 50-tooth ring up front is usable on even varied terrain.

From Sram's website.

The most lovely road 1x that I know is Specialized's super-sweet Allez.

Allez 1x11.  Is that a bike -- or is it a bike?

I keep the Neuvation full-time in Indianapolis where a hill is what an ant makes in loose dirt.  If I'm really mixing it up I may go through four or five gears in the rear, but I never, and I do mean never, drop down a chainring.

So what the hey.

Sram's 52-tooth Force X-Sync Crankset, 172.5mm arms
I selected the Sram chainset.  One thing I like about Sram:  the components look pretty badass.  Campy is pretty and Shimano is functional.  Sram is what John Travolta might have mounted on his car in the musical Grease.

Two ways to achieve a 1x 

Sam gave me the options when I first went down this road.

First is to replace the existing double rings with a single 1x ring, keeping the same crank.  You can find a 1x ring, even a Sram ring, for a reasonable price online.  The downside, of course, is that you lose the benefits of the centered chainring for chainline purposes.

The second option is to replace the entire group.  I was able to piece together the entire Sram Force 1x group for about $700 with parts from different sellers.

There is a non-option:

Ramps.  Beware!
The choice that seems obvious but is not is to keep either your outer or your inner ring and just remove the other. The problem is that chainrings on 2x or 3x cranksets have "ramps," which are tapered teeth designed to make it easier for the chain to move between rings.  Sam tried the "just remove one ring" approach on a single speed several years back and found it prone to derailing.  (There is an old story about a TDF mechanic removing the front derailleur to save weight, and the rider's -- it may have been Tyler Hamilton -- derailing without the derailleur to help guide the chain.)

Cheap but not that cheap

I took a  different, third, tack with the Neuvation.  Instead of a wholly new group, I kept the 10-speed Shimano rear derailler, which works like a charm, and simply replaced the chainset with the Force 1x.  I kept the 172.5mm crank-arms, because I like to really spin it up in the stoplight sprints.  I went with 52 teeth front.  I mean, if you are going in, go all in. 

Sram 1x on the bike.
The Sram Crankset cost $250 from Art's Cyclery.  For $150 you can get the same thing in Rival.  I probably should have done that.

Brifters is brifters.
Those are the original S-105 brifters.  Shimano does not make the ergo-lever for the left like Sram does, so I just removed the shift cable and called it a build.

Producing a clean build

Going 1x means no front derailleur!  That permits you to pull the derailleur cable as well.  In my case I left the housing, trimming it at the end of the handlebar tape.

One day I will remove the tape and pull the cable.
In an ideal world I would have a real chain tool.  That world is not this one.
Of course, you need to break the chain to remove the derailleur.  The old days of front derailleurs that can themselves be taken apart are gone, probably for the better.  When you are going to reconnect the chain using a quick link (which I recommend), you have to remove the "outside" link at both ends.

Bolt-on mount going in the bin.  Probably the parts bin for a while before, ultimately, the trash bin.
With the front derailleur gone, I was happily able to remove the "braze-on" mount, which on the Neuvation is really a bolt-on mount, producing a nice clean BB cluster.  Most modern bikes seem to have clamp-on front derailleurs which would be even better, leaving no bolts remaining.  It would be a tad annoying to make this 1x switch with a true braze-on.  You would be left with the mount.  Not that it matters, but it matters a little.

Nice tight tolerance with the centered chainring.
At the end you use the quick link to reconnect the chain.

Interesting factoid about the Sram X-Sync chainring:  it has an intimate fit with the chain.  I am accustomed to simply laying the chain over the ring and its meshing with the teeth, ramps and all.  With the X-Sync I had to guide the chain onto the teeth.  I almost thought the warning "Sram Chains Only" printed on the ring was accurate.  Of course, it is not.

Then I put the quick-link in place and prepared to step on the pedal to tighten.  (The link needs to be engaged with maybe 30-50 lbs of force, more than I can apply by gripping the chain and pulling.)  I accidentally turned the pedals before the engagement step, running the chain over the ring.  Lo and behold, the X-Sync ring engaged the link on its own (see picture).  I may find on the road that the engagement was not robust, but it sure looks fine to me.

May need a new chain if I go with a larger cassette!
It is a nice, clean-looking build, all put together.  Total time required <1 hour, and that includes making and drinking four cups of coffee.  Total cost $250 -- just the new Sram Force X-Sync chainset.

And here is the bike