First, a brief note on why this review is hitting as the new Tarmac SL4 is being released. I began riding this bike in July for a review that ran on Map My Ride’s site. The reviews I penned for them were, shall we say, necessarily brief. I so fell in love with this bike that I wanted to make sure I reviewed it for RKP; unfortunately, other posts kept back-burnering it, but now the Christmas is almost here and these things are being closed out, it’s worth noting that it’s a good deal better than day-old bread.
When I first began reviewing bikes I didn’t have much in the way of preconceived notions. If I’m honest, some of those early reviews lacked a little something because my criteria for judgment revolved around execution. I was looking for things like sloppy detail work, no clear coat over decals, signs of poor alignment, crappy (cheap) spec and ugly colors.
It took a couple dozen bikes before I realized that my favorite bikes were those with a bit more trail and a low bottom bracket. In fact, the lower the better. On the mountain roads near my home I found that the bikes with the low BBs were easier to control on the descents. They turned in easily and I equated that—incorrectly—with stability.
Eventually, that preference became calcified. I so preferred bikes with a lower BB that I became a bit prejudiced against bikes with a normal to high BB. In concrete terms, my preference was for bikes with 7.5cm of drop, or more. As 7cm of drop is traditional due to CPSC regulations, that resulted in a few rather automatic determinations. First, it put every production bike sold in the United States on the wrong side of the tracks, so-to-speak. All my favorite bikes were at the shallow end of the bell curve because only custom bikes could be built with a BB with more than 7cm of drop.
Not that I cared.
As the industry shifted to carbon fiber, I was faced with choosing between a stiffer, lighter bike, and a bike that sacrificed some performance aspects in exchange for that lower center of gravity.
Almost two years ago I undertook a review of the Specialized Tarmac SL and the Roubaix SL. The two Specialized models helped redeem the company after a spate of crap bikes in the 1990s that caused me to despair that the company had lost its way. When the boys in Morgan Hill made the move to full carbon-fiber models, they did it in a big way and their work was impressive.
There was no escaping my old preferences, though. Faced with the chance to ride a bike with a longer wheelbase, lower BB and a touch more trail and I chose the Roubaix twice a day and three times on Sunday. So accustomed was I to the long and low geometry of the Roubaix I concluded that the Tarmac was a bit skittish, too F1 when luxury sedan was the right response.
I kept riding the Tarmac and my appreciation for it increased, but it wasn’t until I spent a day descending Decker Canyon Road north of Malibu that I figured out just how good the Tarmac is. I did six loops on canyon roads, climbing Encinal (because it was longer and shallower) and then descending Decker (because it was more fun). The first two were on the Roubaix, the second two on the Tarmac then a final loop on each the Roubaix and the Tarmac. I called that post “The Crucible” and while you can read it here, I can sum it up by telling you that by the end of the day I learned that I preferred the Tarmac to the Roubaix on technical descents.
To me, that was tantamount to keeping kosher and then deciding one night that all you’re ever going to eat is pork barbecue. What the?
There was no mistaking that on the tight, technical, twisting descents of the Santa Monica Mountains I prefer the Tarmac. It’s true that I could carve smaller radiused turns, but that didn’t—couldn’t—define the whole of my preference. The biggest piece of the puzzle had to do with how the bike behaved when leaned over. From time to time you’ll hear a reviewer talk about how a bike felt as if it was on rails. That sensation, in my experience develops when you lean a bike into a turn and once you set the lean, the bike continues on that course until you turn the wheel into the turn to stand the bike back up. I have ridden plenty of bikes that once leaned over never settle into a particular line. That’s a problem because if you’re not sure what a bike will do next, you’re apt to hit the brakes and the brakes, we know, are a fun antidote. On the other side, I’ve ridden bikes that just flat-out didn’t want to lean over. I can say the latter is way more problematic than the former.
In terms of pure numbers, my experience is that a BB drop of 7cm combined with a head tube angle (HTA) slacker than 73 degrees and more than 45mm of fork rake will do this noodly line thing. I’ve ridden bikes with an HTA of 73 degrees and 50mm of fork rake, but had 7.5cm of BB drop and they were rock solid in corners. But I’ve ridden others with only 7cm of drop and they were all over the place in corners—just wouldn’t hold a line. Stand them up straight and they tracked true. And the bikes that wouldn’t turn? It was always a BB with less than 7cm of drop combined with a 73-degree HTA and 40mm of rake.
By comparison, the Tarmac in my size (58cm) has a 73.5-degree HTA, 43mm of fork rake and 6.75cm of BB drop. To get a bike with a BB that high to lean over it needs to have fairly aggressive trail; the Tarmac is 5.59cm.
The Tarmac has become my favorite-handling bike on the market. For me, the bottom line of this bike is more objective than subjective: When you need it to change course, it responds with precision, but unless you tell it to do something, it’s going to stay on its present course. I can’t think of a reason you’d want a bike to do anything different.
While we’re covering geometry, I want to shine a little spotlight on the size run for the Tarmac. The bike comes in six sizes: 49, 52, 54, 56, 58 and 60cm. When you consider those six sizes are meant to cover men and that the women’s version of the Tarmac—the Amira—is available in another five sizes, that adds up to 11 sizes in total, a pretty impressive size run. The Tarmac features some significant jumps in sizing that could pose an issue for some in finding the right size bike. The top-tube lengths are, respectively: 51.8, 53,7, 54.8, 56,5, 58.2 and 60.0cm. For the most part, the size jumps are between 17 and 19mm. It means that some riders will need to consider two sizes when looking at the Tarmac. What is encouraging, though, are the number of Specialized dealers that staff someone who has gone through at least the first fitting course (there are several) at Specialized Bicycle Component University.
I’ve shrunk a bit over the years and while I used to commonly ride a 58.5cm top tube, I tend to ride shorter stuff these days. My personal preference would be for a bike with a top tube in the 57.5cm range. With the Tarmac, the 56.5 top tube works great with a 12cm stem, but the head tube length is really short for me and causes shoulder issues. No bueno. So I went with the 58.2 and an 11cm stem. It looked odd, seeing that stubby stem on there at first, but rather than pull a bonehead move and put a longer stem on just ‘cuz it looks better, I rode it and found the bike to be incredibly well balanced. It lost none of the nimble feel that I’d experienced with riding a 56.5 previously.
On steering geometry, the 52 and 54 both feature a 73-degree HTA and a 45mm-rake fork for 5.69cm of trail. That’s not much different than the 56 and 58 which use a 73.5-degree HTA and a 43mm-rake fork for 5.59cm of trail. Where things get a little weird is with the 49 and 60cm sizes. The 49 has a 72.25-degree HTA and a 45mm-rake fork for a sluggish 6.15cm of trail. The 60 has a 74-degree HTA and a 43mm-rake fork for a quick 5.27cm of trail. Some of the slow steering in the 49 will be offset by the fact that it has a short wheelbase. The opposite is true for the 60; its quick handling will be partially offset by a rather long wheelbase; even so, neither bike will feel quite like those middle sizes. Ah to be part of the 99 percent.
Tomorrow: frame stiffness and ride quality.