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Several weeks ago, Shane Stock from Osobike sent us a bicycle to test. I’ve had a chance to ride this bike almost 100 miles, including lots of commutes to and from work and in many weather conditions. With this “first impressions” article, I wanted to address some of the questions our readers had when we first posted about this bike. I also want to talk about some of my initial likes and dislikes. A more formal review will be coming in another couple of weeks…

oso

Several readers had comments and questions about the braking ability of this coaster-brake-based singlespeed. During the course of my riding, I had no problems whatsoever with braking — I’m a longtime fan of the simplicity of coaster brakes and I’ve never experienced any fading or failure of coaster brake systems, no matter how extreme the conditions. But, since I only weigh somewhere around 130 lbs. soaking wet, I decided to recruit two strapping friends of mine from the Seminole Heights Bicycle Club to help me test the bike’s braking performance. Meet Ken Sturrock, dapper gentleman and fan of all types of bikes:

ken

A little background on our “test”: a major bicycle manufacturer was considering the release of their own coaster-braked singlespeed, but they were concerned about stopping distances under a heavy rider. I don’t remember the exact stopping distance they were concerned with, but it was somewhere around 100 feet. There was also concern about meeting the requirements of the California Vehicle Code (which is somewhat vaguely worded as to braking performance of a bicycle). So, after hauling the Oso over to the Bikecommuters.com closed-circuit/skidpad testing facility on my “bicycle tow truck”…

towtruck

…we paced off a 130 foot “stopping area” (white painted lines in the above photo are 10 feet apart). Getting up to a speed of 17-19 MPH, our 200 lb. tester was able to stop without skidding or using the front brake in less than 60 feet. With skidding, the stopping distance was even less. At no time did we feel that we wouldn’t be able to stop in time when needed. My other “guest tester”, Steve Swiger (200+ lbs. of all-American man) also reported no gripes with the braking performance of the Oso.

Another question/concern of some of our readers was about the possibility of mounting fenders to the Oso and whether there was enough frame/fork clearance to mount cushier tires. As many of your noticed, the fork of this bike is equipped with fender eyelets…and that is a real mystery to me, as there is NO WAY to mount even a narrow fender between the legs of this fork (well, actually, there IS one way, but it requires a “River City Reacharound” and cutting a fender into two pieces…not an elegant solution). Here is a photo that illustrates the clearance around the front brake caliper and the fork crown:

clearance

Not much room around there, is there? I’m going to chalk up the fender eyelets to “unsolved mystery” status — I’m having a hard time figuring out why the Taiwanese frame manufacturer even makes a fork model like this!

How do larger tires fit? 23 mm tires aren’t everyone’s cup of tea, so I wanted to mount some cushier rubber just to see if such a thing was possible. I happened to have a pair of 28 mm road tires on hand, so on they went:

28s

There’s a few millimeters of room to spare on either side of the tire. I’m guessing that a tire up to 32 mm wide would probably fit, but if it were up to me, I wouldn’t go bigger than 30 mm. The same applies to the rear of the bike — there’s a bit of room to spare, but not much. No knobby cyclocross tires or plush “fatties” on this bike:

more 28s

The wheels on the Oso are made by Alex. These aren’t run of the mill Alex wheels, though — they’re drilled and laced under a patent by Rolf Wheels. The wheels themselves aren’t particularly light — they are 36-spoked models and the hubs are nothing to write home about — but they have performed quite well on Tampa’s notoriously rough streets. After the wheels “settled in” (the initial creaking and popping of most machine-built wheels), they have withstood many trips down brick-paved streets and even a few stairways without coming untrue. Nice!

Ok…now for an aesthetic concern and two serious performance concerns. I really like the clean lines of the bike and its dazzling white color scheme with subtle silver decals. I especially like that Shane has specified a silver stem and seatpost for the bike (when was the last time you saw anything but black components on budget bikes?). That being said, this silver component scheme should have and could have been carried throughout the bike — especially the crankset:

crankset

This crankset looks out of place on such a sleek bike…and guess what? It IS out of place! This crankset is a modified mountain triple (the mounts for the innermost chainring have been somewhat crudely ground off) — far better suited for a freeride or all-mountain bike than a singlespeed road machine. And, with a mountain bike-standard bolt circle diameter of 104 mm, finding big chainrings to replace the existing one or to modify the gear ratio isn’t an easy feat. Despite extensive Web searching, the biggest I’ve found is a 48t, same as the original chainring. Want to go bigger? Good luck, and happy searching. Smaller chainrings are readily available, though, so adjusting the gear ratio won’t be too daunting for folks who like to tinker.

That brings me to the first of my performance concerns: specifying the crankset used on this bike may contribute greatly to the poor chainline this bike suffers from. As many of you surely know, chainline is crucial on a singlespeed bike. A straight chain is a smooth one, and a straight chainline prevents undue wear from chewing up the cog and chainring and also minimizes the possibility of throwing a chain while pedaling. Using Sheldon Brown’s chainline calculation methods, I determined that the rear chainline measurement is 41.5 mm and the front chainline measurement is a hair over 50 mm. 2 or 3 millmeters of difference is ok; nearly 10 mm is NOT. While I haven’t thrown a chain, I can hear and feel some pretty serious grinding going on, even after a liberal application of chain lube. The bottom bracket spindle needs to be replaced with a shorter model.

The other concern was pointed out by one of our commenters on the original article…the chain is too tight, and there’s no adjustment available to give it some slack. The rear wheel axles are all the way to the front of the forkends. This chain desperately needs an additional full link…and while I could have added a link and swapped out the BB for a shorter spindle, I refuse to do those sorts of things while testing a bike. If a bike comes like this from the manufacturer, that’s how it’s going to be tested!

In the review, I will discuss how the bike rides…but until then, I leave you with a couple thoughts — the Oso is fun, it’s simple and it is pretty sleek. Oh, and it can be VERY fast. None of my gripes are difficult to surmount…a little tweaking here and there can eliminate most of my concerns.

Steve and Ken, guest testers