Gravel Mutt v3: Return Of The Gravel Mutt

Well, it is finished up. The third "gravel mutt" from Guitar Ted Productions! (HA!) The bike is a Schwinn, but this seems to be an outlier in Schwinn's catalog at that time, and because of that, it is a very interesting "throwback" to an earlier time. Let's dig into the foundations of this bike and why I feel it is representative of a timeline that goes from the early 20th century to the modern day gravel bike. 

As I mentioned on Saturday in "Two Things", this bike stood out to me immediately due to its odd geometry. Odd for the time it was built, that is. To understand this, one needs to understand what the geometry of American road bikes was leaning towards in the late 1980's/early 1990's.

By this time road bikes were starting to evolve into the American version of a racing bicycle, namely a criterium bike. Criterium racing was the predominant form of road bicycle racing by this time and was definitely more popular than road stage racing. Roads were hard to close down for a safe cycling event, and it was easier to manage a closed circuit, gain attendance for spectating, and sponsors loved the idea more than open road racing. 

This drove geometry to become more adept at the style of riding criterium racing demanded. A high bottom bracket was preferred for high-lean angle cornering and pedaling. A shorter wheelbase was preferred for it's stiffness and agility, as was a steeper head tube angle than what had been dominant in the bicycle world previously. 

Head angles crept steeper and most landed on a 73° head angle, but some more extreme geometries went to 74°. Bottom bracket drop was less than 70mm on most criterium based geometries, but commercially, 70mm was a pretty common bottom bracket drop. Seat tube angles steepened as well since sprinting out of corners was a demand of criterium racing, so weight distribution on many late 80's early 90's road bikes was more forward, over the bars than laid back into the saddle. 

1988 Trek 1000 from ebay.

Okay, so that was the lay of the land for road bikes. Now lets get to why this particular Schwinn model stands out from that crowd. I noticed it as soon as I laid my eyes on the bike. The head angle was waaaay slacker than this era of bike would normally have. Hold on here! 

Moreover, the bike, which was fitted with 27" X 1 1/4" tires, had tons of clearance to the frame. Hmm.... And the bottom bracket drop was noticeable. I had to investigate further. I grabbed my iPhone which has an angle finder app on it. A quick measurement of the head tube yielded a 71° degree measurement. I was surprised, so I measured again, and once more, just because I couldn't believe that a 1980's era Schwinn would have such a slack head angle. But it looked to be what my phone kept telling me. 

So, I decided to do a quick and dirty bottom bracket drop measurement. I strung a piece of masking tape from the rear drop-out to the front for drop-out and measured from that horizontal line to the center of the bottom bracket. It looked to be more than 70mm, maybe close to 75mm. Again, this was just to get an idea, it wasn't a precise method to obtain this information. I just wanted to understand if this would be a worthwhile project before I made a third mistake in trying to come up with another Gravel Mutt. 

1989 Schwinn World Sport, 58cm (ctr - top), set up as a single speed.

So, here it is, all finished up. I traded out all the components with the exception of the head set and brakes for stuff I had. 700c wheels I had built which use Dura Ace thread-on freewheel hubs. Salsa Delgado Cross rims shod with 37mm Panaracer tires. A BB-90 Shimano cartridge bottom bracket with a Shimano 105 crank and a 38T chain ring turning a Shimano 20T freewheel. A SOMA threadless adapter is clamped in a Ritchey Classic stem with a Salsa Cowbell bar and Tektro brake levers. I used a longer 26.6mm seat post, (the original one was super-short), and topped it off with an older Ergon SM-3 saddle in white. Some pink bar tape to give it that late 80's vibe finished off the look and a set of old Shimano SPD's will allow me to pedal this beast along. 

I ended up using a Surly Singulator to tension the chain, but if I wanted to, the drop-outs could be machined and made into semi-horizontal type which could help with chain tensioning. But this set up will do for the time being. 

I could probably Dremel out that drop out but this will do for now.

Single speed, of course! Simple and it keeps me focused on how the bike rides and performs. That will be my aim going forward because as I learned, the geometry is even weirder than I first thought. First off, I found a scan of Schwinn catalogs from the 1980's online and I searched them until I ascertained that this bike is a 1989 World Sport. The World Sport was nearly the bottom of the range Schwinn road bike at that time, and it was, probably, the entry level road bike. Only the Schwinn Voyager is shown below it in the specs, but that was a touring bike, of course. 

The catalog showed the basic geometry measurements of head tube angle and seat tube angle only, and that for the 23" frames. Weird. But since this example just happens to be a 23" frame, it can be assumed that the data in the catalog is taken from this size in the range, or can it?

The head tube and seat tube angles listed for most of Schwinn's road bike line up go from 72.5 (Voyager) to 73° for nearly everything else. But the World Sport lists a 72° head angle, the slackest of the entire road bike range for 1989 Schwinns. But hold on! My on-the-shop-floor measurement with a gravity gauge and my iPhone say this bike has parallel 70° seat/head tube angles! And compared to my gravel bikes, you can see it. 

Just enough clearance for these 37mm tires.

Why is the Schwinn World Sport, and this example in particular, so odd compared to everything else Schwinn was doing and what most road bike companies were doing at the time? That's hard to say. My guess is that since this was meant to be an "every-man's road bike" that the geometry needn't be like a racer's. The spec could be off because this bike was made, most likely, in Japan or Taiwan and since that was the case, QC may have been a bit lax. Maybe this single unit is an outlier to the entire range? That could also be the case. 

Whatever the case may be, this will be a fun and interesting gravel mutt experience. Now as for the timeline of geometry and this bike, I feel that this bike and its geometry are really pretty close to what we were looking at with the Honeman track bike from the 1930's, and which was the dominant rough-road geometry for bikes from the early 20th century that best translates to what modern gravel bikes need and are.  

So, the questions are will this be anything like a modern gravel bike experience? Will this bike actually point to something that even more closely defines what geometry will be best for gravel bikes? Or, will this be a revelation in how this geometry isn't quite right?

That and more is to come. Stay tuned.....