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Originally Published May 2, 2007

In the 650B Conversion Guidelines article recently posted to this blog we showed you some preliminary photographs of a new Soma Fabrications Speedster frameset sitting on 650B wheels. We've just finished assembling and testing that bike, and I'd like to tell you more about that project in this article. I've been looking to identify and prove a few new 700C production bicycles for conversion to 650B.

Complete bikes are easier and can be less expensive to convert since they come assembled and configured with most of the parts that you need. But there are some fine new 650B convertible framesets available these days, and they make for interesting projects, too. In the case of the Speedster, there is no equivalent complete production bicycle offered on the US market. And even as a frameset, it's quite a unique offering.

Being an old-school kind of guy, when I first learned about the Soma Speedster frame I was very interested. Here's a new production frameset that uses Tange Prestige steel, with chrome plated head lugs, and it's supplied with a matching steel fork built with Tange Infinity blades and a chrome plated cast crown. It looks classic, but it also has the features you'd expect in a modern road bike frame; it uses a standard 1-1/8 inch threadless steerer, it has braze-on fittings for two sets of water bottles, there are down tube shifter bosses that can accept STI or barcon cable stops, and the frame has a really nice looking investment cast bottom bracket shell with cast-in cable guides and a yoke shaped cutout. The folks at Soma have thoughtfully provided attachment points for fenders on the dropouts and threaded bosses on both of the rear stay bridges. And, furthermore, they picked a rich looking red garnet color scheme with tasteful if somewhat bold graphics. It's an elegant looking production frameset, and that's a somewhat rare commodity these days. I used to say that they don't make frames like this anymore...

But here it is. It reminds me of the high quality Japanese production frames built in the early '80s. This new frame is just too tempting to pass up! And it gets better; because the frame is designed to accept 32mm 700C tires and it has a 7cm bottom bracket drop. This is good for 700C configurations, and these are also good parameters for conversion to 650B. Now, I need to be up front and state that the Speedster was designed for 700C wheels, so building this bike in a 650B format isn't officially sanctioned by Soma. But the Soma photographs, geometry numbers, and specifications all looked right for 650B conversion, so we ordered one of these frames in my 54cm size for our next potential 650B conversion project. Right out of the box, the frame looked promising. The workmanship was very good, and the clearances all looked and measured about right. We propped the fork in the frame with some rubber washers, and put a set of 650B wheels in it to get a better sense for how well it would work. Then we took it outside and shot the photographs that you first saw in the last edition of this blog. Everything looked right, so we decided to proceed with the project. BTW, I found that the seat tube measurement on this 54cm frameset was taken to the top of the point of the seat lug, so the frame measures more like my 53cm bikes. And the head tube is not extended, which means that getting the handlebar up at saddle level requires extra headset spacers or an up-riser stem. You might want to keep that in mind when you order your Speedster. If you're between sizes you may want to size up. Anyway, like all good 650B conversion candidates, there are no modifications whatsoever required to this frameset to run the 650B format, so there is no risk in building it with 650B wheels.

The bike can be quickly reconfigured to 700C by simply swapping the brake calipers and wheels. And like most of my other 650B converted bikes I know that the bottom bracket will be a just little lower than most production bikes, so I'm cognizant of that to avoid pedal strike when cornering. Since this frameset was going to be first built as a 650B rig, I got to wondering: Hmmm... is it still a "conversion" if you build it as a 650B rig right from the start? Maybe we need a new term: 650Built. Now, the fun part of building up a complete bike from a bare frameset is that you get to pick every part to your own specification and preference. And being the bike freak that I am, I have some components stashed away that I decided to use on this project, so the finished machine is uniquely my own. But as part of the exercise, I made up a list of components for a Soma Speedster 650Build kit from the Bikeman web store, and we've provided that list for those of you who might not have such a parts stash. You'll notice that I tried to keep the component choices suitable for the frameset, and I maintained a traditional appearance with the use of silver finishes wherever possible. The bike I've spec'd out will actually look very similar to the example shown on the Soma Fabrications web page, albeit it's a 650B version like the one we've done here at Bikeman.

The Speedster has stable yet lively geometry, it isn't designed for front-loaded bag carrying, there are other bikes such as the Kogswell P/R which are meant for that. But with those 650B wheels and a small saddlebag the Speedster makes for fun, fast, adventurous day-touring, which is what I do most of the time. This configuration reflects that kind of anticipated use.

When I build a bike, I like to stage the components prior to the actual assembly of the machine. In this way I can test-fit the pieces to see how everything fits, looks, and measures-up. It's a good method to sort out the components before they're committed to the build. But you really need to have the fork installed in the frame, so the first piece that I select and install is the headset. We used an FSA Orbit X headset because it's a good value and a solid performer with trouble-free cartridge bearings, and it looks right on the Speedster. Once that was in place I started the component staging. After I had a good mix of components chosen and sorted out for this bike, I pulled them off and treated the interior of the frame with JP Weigle's Framesaver to protect against corrosion. After all, this is an all-roads, all-conditions kind of bike, so it's going to get wet at some point. In my opinion, every new steel bike frame should be treated with Framesaver before assembly.

I decided to equip the Speedster with a traditional triple crank configuration. I've found that the versatility of the triple crank gearing gives the me ability to find a good cadence on the variety of surfaces that the 650x38B wheelset can comfortably travel.

I used one of my last, rare, NOS Sugino PX cranksets. This is one of the most noticeable personal pieces of kit on the bike. I also had the NOS SunTour front derailleur, and it works well with the PX and this frameset. BTW, this first run of Speedster frames has the lower water bottle boss in a place that may conflict with the mounting of some front derailleurs. The size of the big chainring will effect this. Soma has an adapter/hanger that can be used to mount a braze-on derailleur above the boss, but with a 48-tooth big ring I was able mount this SunTour XC Expert below the boss. The PX has a traditional square taper bottom bracket interface, so I installed a new sealed cartridge bearing bottom bracket with a 3mm spacer under the drive side cup to provide clearance for the granny ring, and to put the middle chain ring in line with the center of the cassette. This was the trickiest part of the build, and something that you won't need to do when you use a standard new-production crank and its corresponding bottom bracket.

I've had good results with 8 speed components, and this bike uses them in conjunction with a 9 speed rear derailleur for the best combination of durability and availability. There's a silver 9-speed Shimano 105 derailleur in back, Bikeman has a few of these available in the web store. The traditional 8 speed Shimano barcon shifters work well and are nearly bulletproof, too. The gearing is 26/38/48 mated to an 11-28 cassette. This provides a very practical range, with a low gear of 24 gear inches, and a high gear of 113 gear inches. Most importantly, I've found that the 38 tooth middle ring gives me some very useful cruising gears in the middle of the cassette where I ride most of the time.

Of course we used the new Tektro R556 dual pivot caliper brakes! The rear brake pads are perfectly adjusted at the bottoms of the slots on this frame. The front pads have a little more downward adjustment available. Yes, those dual pivot calipers work very well on this frameset. However, I did swap the stock brake inserts for a set of Kool-Stop Dura-Type salmon pads. I've found that they simply stop better than the original black Tektro inserts.

Saddles, handlebars, stems, and pedals are all a matter of personal preference. I like the San Marco Rolls saddle, and the gold trim on the Rolls compliments the gold lettering and graphics on the Speedster. I prefer Nitto model 177 "Noodle" handlebars for their long ramp section and smooth bend profile, and the 44cm width makes a nice wide cockpit. Wrapped up with Cinelli cork tape it's a very comfortable hand-hold. To match the chrome head lugs, we used a chrome plated Syntace stem, and I polished up an older aero section Shimano 600 seatpost to a mirror finish for a complimentary look there.

I especially like the way the aero post tapers above those semi-fastback seat stays. With respect to the stem angle, I tried to keep the appearance of the bike as traditional as possible. This meant installing the stem in the downward angle position, and using more headset spacers. After cutting the steerer tube I'm confident that the front end will be solid; it took some time to cut through that thing, that's some tough steel!

I really like clipless pedals, I've ridden LOOK clipless pedals for years. But when I'm on these 650B rigs, I want to be able to walk around easily, to carry the bike through a rough section, or hike around in a new area. Sometimes I want to go into a cafe' and have lunch. SPD shoes tend to be easier for walking, so this Speedster has SPD pedals, and keeping with the silver color scheme I opted for Shimano's PD-M540 pedal with the svelte allen attachment spindle.

The SKS P-45 fenders are hard to beat for use on 650B conversions, and the silver version looks really good on the Speedster, matching the downtube lettering and the lower part of the head tube decal. You'll notice that I used aluminum spacers at the bridge mounts for the rear fender to improve the fender line. I typically put blue threadlocker on these screws to keep them in place.

The front fender bracket is between the front of the fork crown and the brake, and I bent the tang away from the fork to clear the lower headset cup. Once the fenders were fitted and adjusted, I marked the stays at the edge of the fender, and cut them to length. This is safer than having those stays protruding out beyond the fender, and it eliminates the need to use the plastic protector caps.

As a final bit of tweaking, I used a hair dryer and a little pressure to adjust the shape of the front fender for a better fit and appearance. Okay, now you know all my SKS fender tricks, so there's no excuse for sloppy fender lines!

The wheelset is borrowed from another bike. It's a good quality handbuilt pair, with Shimano cassette hubs, 32 hole Velocity Synergy rims, double butted spokes and a pair of NOS Mitsuboshi Trimline tires. Those tires are no longer in production, but we're hearing rumors about a new high performance 650B tire, and I can't wait to try a set on this bike when they're available. We'll keep you posted on that development. I just got a set of the new CTA Velocity Aerohead 650B rims. When they're built I'm planning to test them on this machine. That wheelset may be a mini-feature in a future edition of the 650Blog.

I've had a chance to ride this bike, and it's real performer. You already know that those puffy 650x38B tires ride like a dream; absolutely zero road buzz or vibrations get into the bike through those tires. It handles like a good modern sport bike; it's stable, yet quick to respond. It's easy to ride no-hands over a wide range of speeds. It accelerates quickly and stops controllably. Like most modern frames with 1-1/8 threadless steerers, the front end of the bike is solid; the handlebar feels like it's connected directly to the front axle. Steering is very direct, and the bike is virtually unaffected by transitions across road irregularities at acute angles. Ride it off the pavement onto the shoulder, and back onto the pavement - at speed. Point it, and it goes there. And of course, for most people, those tires can handle almost anything shy of real mtb technical stuff, too. Broken, bumpy and rough pavement: no problem. Dirt roads: gas-it! A little single track here and there... let's go! You'd probably crash a skinny tire 700C road bike doing most of this stuff, and the big 35mm+ 700C tires would feel slow in comparison to the 650x38B.

So here it is: The World's First 650Built Soma Speedster. It was quick and simple to build, no modifications of any sort were required to the frame or components. It's great fun to ride, it all works beautifully, and personally, I think it's a sharp looking bike.

Perhaps the best part is that you could have your own 650Built Soma Speedster! Bikeman can make that happen for you.

Okay, I'm going out for another ride!

Ed 650Braley