Saturday, April 19, 2008

Fixx Your Singleator

So I've refused to give up on my Surley Singelator for my singlespeed chain tensioner, I have just way too time and money much invested in this stupid little part to let it overcome me since I now own three of them. I've come to the determination that this is a simple case of over engineering a simple solution. This is pretty much it for parts, minus the pulley wheel.
The Singleator relies on loading an internal spring to put tension on the chain. That task requires bolting the arm onto you derailleur hanger and using an 18mm cone wrench to pre-load the spring as you tighten the arm down. Nice idea, poor execution. The notches for the cone wrench on the aluminum sleeve are too narrow for any wrenches I have causing the cone wrench to get trapped between the arm and the hanger making it impossible to get the cone wrench out once tightened.
Problem lately with them is two fold, the spring never holds enough tension to keep the chain tight and second, the internal threads of the arm strip out for the bolt that holds the pulley assembly rendering the whole thing useless. Basically I have two stripped out arms and only one pulley wheel that hasn't been sucked through my drivetrain after the bolt loosened up while riding.

Today I finally remembered why I was running a 32x15, because it was the only gear configuration that worked to put enough tension on the chain. This all fell apart though after I put on a 17T cog to go pre-ride the Greenbrier course. As soon as we took off up the first hill, the dreaded sound of my chain skipping over the cog, slipping off the teeth. Then on the first downhill I hear what sounds like coins hitting the pavement and look back in horror at my rear wheel to see the entire pulley assembly gone. Fortunately it all landed relatively close together and I found all of the pieces. Needless to say this meant for a frustrating day. I managed one lap, at the start of the second, Sean's rear derailleur cage sheared in half so that was the end of the day since he was my ride.

When I got home I went down to Avalon Cycles since they cater a wider variety of riders and have some boutique parts in stock. Although I didn't find a Soul Craft chain tensioner or similar design that does not require a spring, I did talk to one of the shop employees who had converted the Singleator on his trials bike to not need the spring. He accomplished this by grinding down the aluminum sleeve that holds the spring in place and has the useless notches for the cone wrench.
This solves two problems, first it allows the arm to to be bolted tight against the hanger and second there's no more messing around with the cone wrench to adjust the tension. Just set the tension when tightening the arm to the hanger and you're done. I just converted mine and it works great, still need to hit the trails with it for a good dirt session but it's definitely promising. It does require carrying a 5mm with you to loosen it should you need to remove the rear wheel but at least it works.

Simple solution to a simple problem.

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