In a previous post, we mentioned the Eccentric 46 Bottom Bracket for use with PressFit-30 (PF30) bike frames. This aftermarket accessory allows you to be able to purchase a geared PF30 frame or bike and easily convert it to a single speed. But what about those of us who do not own a frame with a PF30 frame? Are we left out in the cold? Nope! There are solutions out there for those of us with the standard bottom bracket shell.
I know what you are thinking; what about the Surly Singulator (right) or similar type of chain tensioner? That solution will work with any frame that has a rear derailleur hanger. That is a great option, but it is not that clean looking of a solution and you can not safely run a singulator in a fixed gear setup.
OK, what about a the White Industries eccentric ENO rear hub (below)? I personally really like the products that White Industries manufacturers and this a good solution, but there are a number of drawbacks to the ENO rear hub. First it will also require the use of their Disc Eccentric Mount if you have rear disc brakes along with needing to lace up a new rear wheel.
Also, when you are on the trail and have a flat tire, the ENO hub requires a wrench to re-tension the chain upon installation of the rear wheel. Finally, you can not run a quick release skewer. Plenty of people use the ENO rear hub and I even have one in my garage, but there is an even cleaner solution.
In recent years, with the advent of cranksets using bottom brackets with outboard bearings, quite a few manufacturers have come out with a novel solution – outboard bearing eccentric bottom brackets (OBEBB). These OBEBB allows you to convert a bike frame with a standard bottom bracket shell cleanly and without having to adjust your rim brakes, buy an adapter for your rear disc brake or lace up a new rear wheel. Plus this solution allows you to setup your bike as a fixie if you so desire. Compared to other bottom brackets, these OBEBBs can seem quite expensive, but if you add up all of the parts to achieve as clean and versatile solution as the ENO rear hub, they both should come in at about the same price.
The Philcentric by Phil Wood
The Philcentric (left) is designed for integrated spindle and crank systems, but in the Phil Wood fashion, they have made the cup available in the following thread specifications: English 1.370 x 24 tpi and Italian 36mm x 24 tpi. The Philcentric is for the integrated spindle crank specifications used for Shimano, FSA and RaceFace, but they did not leave SRAM out of the mix. Phil Wood has also manufactured an adaptor that enables one to use a standard Philcentric cup with Truvativ and SRAM cranks. The only major player left out is Campy, at this time Campagnolo cranks are not currently compatible. Campagnolo uses a center bearing on their crankset that interferes with the Philcentric bottom bracket.
The Philcentric does has distinct fixed positions. During the tightening process of the chain, only 15 degree increments are available. For most people, this may not be an issue, but during installation, you should have a half-link ready if you can not adjust the chain tension properly.
The downside of the Philcentric OBEBB is that the installation requires the use of the Phil Wood Philcentric installation tool which is only available to bike shops. Most shops are not going to buy this tool if you are the only person wanting this OBEBB, but if you are lucky enough to find a shop that can install the Philcentric OBEBB, the initial install is the only time this tool needs to be used. Once both sides of the Philcentric are installed and aligned, you can make all of the chain tension adjustments using just a small hex wrench.
The Philcentric can be ordered through most bike shops and is available in only one color. The weight is a little heavy, coming in at 356 grams and they can be found online for under $250 if you do not have a local shop that is willing to order you one.
Tr!ckStuff Exzentriker
The Exzentriker (right and below) is the same type of solution as the Philcentric, but is not limited to the 15 degree distinct fixed positions, it has infinite adjustment positions. The German company, Tr!ckstuff, has been manufacturing the Exzentriker in six different colors for almost five year, but it currently only works with cranksets that have a 24mm axle (ie. Shimano, FSA and RaceFace) and English 1.370 x 24 tpi threaded bottom bracket shells.
Another advantage over the Philcentric is a special tool maybe required, but it is sold to consumers. The Exzentriker is 140 grams lighter than the Philcentric, weighing in at 216 grams.
The downside of the Exzentriker is that it is from a German company – good luck finding one in the States. I only found one online retailer carrying the Exzentriker for $285.
Others
There have been other companies who have produced OBEBBs and even a couple of non-outboard bearing solutions, but it is unknown at this time if these products are being made. One name that keep appearing during my search of OBEBB was Forward Components. From the photos I have seen, they had a much simpler solution than both Tr!ckStuff and Phil Wood an the reported price was also half of what the other two companies are selling their OBEBB for today. Unfortunately, there is no indication that Forward Components will be back in business, but search for their name before settling on your final OBEBB purchase.
With any of these solutions, some modifications will be required. You will need to also purchase a spacer kit and single cog for the rear cassette. The small chainring may need to be removed and the mounts for the small chainring even ground away. A half link may need to be used to properly tension the chain depending on your gearing selection. Ultimately, there should be no need to modify the frame, but nothing is for certain until you are finished with your single speed conversion. If you have an older bike that you just do not want to give up and the knack for tinkering, one of the OBEBB solutions maybe just what you are looking for to simplify your ride.