Basso Diamante SV Disc review

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The Diamante has been the premier carbon road frame in Basso’s catalogue for several years, however it has always been a largely traditional offering. That is until 2017, when the company unveiled the Diamante SV, an aerodynamic version of the flagship model, followed by the addition of disc brakes for 2018.

In terms of keeping pace with the market, Basso’s entry into the aero road bike realm is obviously late, and as Matt Wikstrom discovered, it trails behind what the best of the market has to offer.

Story Highlights

  • Purpose: Racing and aggressive riding.
  • Highlight: A robust frameset for powerful racers.
  • Material: Carbon.
  • Brake type: Disc (rim also available).
  • Key details: Aerodynamic design, BB86 bottom bracket, 12mm thru-axles, flat mount disc brakes, integrated seatpost clamp.
  • Price: Frameset, AU$7,125/US$5,895/£3,750/€4,439.
  • Weight: Frame (size 56), 1,288g; uncut fork, 420g; seatpost, 211g; stem (110mm), 209g.

Basso Bikes is a proud Italian company that celebrated its 40th anniversary in 2017. Founded by Alcide Basso, the company grew out of the garage where he started building his first steel frames in 1974. He had the help of his two brothers, the oldest of which was Marino, winner of several Grand Tour stages and the 1972 World Road Cycling Champion.

Basso soon developed a strong reputation for the quality of its steel frames and continued using the material into the ‘90s before embracing aluminium, titanium, and eventually carbon fibre. Alcide enjoyed experimenting with the new materials, but his primary drive was always focussed on improving the performance of Basso’s products.

When other proud Italian brands such as Colnago, Bianchi, and Pinarello started looking to Asia for help with manufacturing, Basso Bikes remained steadfastly committed to maintaining its facilities in the north of Italy, near Vicenza. In an era when “made in Italy” does not always mean that the frame is actually constructed in an Italian factory, Basso’s fleet of carbon bikes are all local products.

Basso Diamante SV aero road disc bike

Adding an aero race bike to the range

As mentioned above, the Diamante has been Basso’s flagship road bike for several years, and in that time it has undergone a few revisions. We reviewed one of the earlier versions in 2013 while the latest iteration was unveiled at Eurobike this year. Throughout it all, the Diamante has remained a racing thoroughbred, though very few allowances were ever made in the name of aerodynamic performance.

“Aero is everything” has become a familiar catch cry in the current road bike market and enthusiasm for marginal gains has overtaken the professional peloton. Race bikes are now sleeker than ever and there is something of an expectation that any performance-oriented bike needs to slip through the air with the help of Kamm tails, integrated seatpost clamps, and hidden cables.

As a small manufacturer, it’s easy to understand why Basso was slow to respond to enthusiasm for aero road bikes. After all, it’s one thing to present the market with a new bike, but it’s another to expect shoppers to pay for it.

Basso Diamante SV made in Italy

As late as Basso was to the aero road bike party, it did not rush the development of a suitable bike. According to the company, two years were devoted to creating an aerodynamic version of the Diamante, which was dubbed the Diamante SV for its 2017 debut.

“Super Veloce” is what the SV stands for, which translates to “super fast” in English. That alone is enough to sum up how Basso feels about the new bike, however the company is quick to point out that it never wanted to create a bike that was aero at all costs. Aesthetics, weight, and serviceability were all overriding concerns, which meant Basso was only prepared to go so far to improve the aerodynamics of the new frameset.

Be that as it may, the Diamante SV exhibits many of the touches that have come to define modern aero road bikes. A broad Kamm tail serves as the down tube of the new bike, with another slimmer version for the seat tube and post and an integrated clamp to preserve its sleek shape. The lowered seatstays are also a familiar sight, as is a seat tube that follows the curve of the rear wheel.

Kamm tails are used for shaping the down- and seat-tubes of the Diamante SV.

According to Basso, a NACA algorithm was used to design the aerodynamic profiles incorporated into the Diamante SV, however no wind tunnel testing was carried out to prove the efficacy of the design. There’s no data from benchmarking studies either, which will disappoint aero-weenies.

Interestingly, independent testing by Tour Magazin determined that 220W was required to drive the rim brake version of the Diamante SV with a 50mm carbon wheelset at 45km/h. By comparison, the same publication reported 207W for Cervélo’s S5; Giant’s new Propel came in at 209W; Canyon’s Aeroad, 211W; and Scott’s Foil Premium, 215W. At the other end of the spectrum, Trek’s Émonda required 239W; Giant’s TCR Advanced, 235W; Scott’s Addict, 229W; and Canyon’s Ultimate, 226W.

Thus, on the basis of these results, it appears that the Diamante SV is a modest aero performer, offering buyers some free speed, true to Basso’s claims. In absolute terms, though, the Diamante SV is not quite as sleek as some bikes, so aero-weenies won’t be wooed by Basso on this occasion.

Basso Diamante SV aero road disc bike

The finer details

There is more to the performance of a bike than simply cheating the wind, though. One look at the change in direction for the design of the new Venge is all that is needed to confirm this notion. For Basso, it was important that the bike remained stiff and light, hence the use of Torayca high modulus fibres (T800 and T1000) throughout the Diamante SV Disc. According to Basso, a size 53 weighs in at 820g without paint, which has to be counted as a pretty feathery result.

The specifications for the Diamante SV Disc are familiar by modern standards: the headtube is tapered with a 1.5inch lower headset bearing and a tapered fork steerer to match; BB86 shell; 12mm thru-axles, front and rear; flat mount disc brakes; and internal routing for the brakes and gear cable/wires. For the last, the frame is supplied with interchangeable fittings to suit both electronic and mechanical groupsets.

The frame makes use of a proprietary seatpost design with an integrated clamp that sits at the rear of the seat tube. Dubbed Basso-3B, the patented system is akin to a large brake pad that grips the seatpost. A pair of grub screws takes care of adjustment, while a third bolt keeps the “pad” in place when the post is removed. Finally, a rubber gusset surrounds the post with the promise of reducing vibration.

Basso’s integrated seatpost clamp is very neat but tiny grub screws can become problematic.

With a long and low front end and short chainstays (400-406mm, increasing with the size of the frame), the geometry of the Diamante SV Disc is aggressively race-oriented. Buyers have a choice of seven sizes, as shown in the table below:

Basso Diamante SV Disc frame geometry

The stack of the Diamante SV Disc can be moderated by 20mm by fitting Basso’s “comfort kit” that is included with the frameset. This is a moulded spacer that fits neatly into the upper bearing race of the head tube and integrates with the top tube. Basso doesn’t provide any numbers for the stack and fit of the frame with the comfort kit in place, but a 20mm increase in stack should decrease the reach ~6mm for every frame size.

Also missing from Basso’s geometry charts are details on the fork rake/trail and bottom bracket drop, and a request for this information was ignored, so the company clearly considers it proprietary knowledge. Interestingly, Basso makes use of the same top tube length, head tube angle, and seat tube angle for all of its road frames, so I wouldn’t be surprised if the trail and drop were also part of a time-proven formula.

The stack of the Diamante SV can be adjusted
Basso’s “comfort kit” allows the stack of the frame to be increased by 20mm for a more relaxed fit.

The Diamante SV Disc has an imposing, muscular presence that almost demands a mid- or high-profile wheelset to complement its bold lines. The heavily fortified junctions of the frame add to this effect and raise expectations that the chassis will be stiff and unyielding. As for the finish, Basso currently offers four choices: pastel white (tested), black-anthracite, blue-orange, and white-Italia.

The weight of the 56cm frame sent for review by Basso’s Australian distributor, Dawson Sports Group, was 1,288g (without thru-axle or headset). That’s significantly more than the promised 820g for an unpainted 53cm frame mentioned above: the luxurious gloss finish probably accounts for most of the extra weight along with the seatpost clamp, rear derailleur hanger, and cable guides that were included in the weight of the sample frame.

The uncut fork supplied with the frame also suffers with the weight of paint, weighing in at 420g. The combined weight — 1,708g — is a lot for a modern race chassis, even after allowing for the extra weight associated with disc brake fittings and thru-axles.

Basso adheres to the current trend for road disc bikes by utilising 12mm thru-axles and flat mount disc brake callipers, front and rear.

The Diamante SV Disc frameset is shipped with a seatpost, headset and spacers, comfort kit, and an alloy stem. There is only one option for Basso’s proprietary seatpost — 15mm offset — while there is a choice of lengths (90/100/110/120/130) and two angles (0° and 11°) for the stem. The latter is not a strict requirement since any standard threadless stem can be installed on the bike (though at least one spacer will be required to cover the upper the upper headset bearing).

For this review, the Diamante SV Disc frameset was assembled with a SRAM Red eTap HRD groupset (including a Quarq Dzero power meter), alloy FSA bars, Fabric Scoop saddle, and Industry Nine’s i9.65 Disc wheelset fitted with 28C Vittoria Rubino Pro tyres and butyl tubes for a final weight of 8.08kg (without pedals or bottle cages). A switch to i9.35 wheels brought the weight of the bike down to 7.88kg, but that’s still a fair bit of heft given the calibre (and expense) of the parts used for this build.

As for the other important number, the price, the Diamante SV Disc frameset is expensive: AU$7,125/US$5,895/£3,750/€4,439. That price includes the frame, fork, headset, seatpost, thru-axles, and stem, plus a three-year warranty.

Basso Diamante SV aero road disc bike

Stiff and Sturdy

I really enjoyed my first encounter with Basso’s Diamante, so I was looking forward to riding the Diamante SV Disc. Based on looks alone, I was expecting a stiffer and more robust bike, and that’s exactly what I found.

From my first moment on the bike to the last, it was incredibly sturdy, and yes, very stiff. But this was not just a matter of how sure the bike felt under load when I was sprinting out of the saddle. The front triangle was just as rigid as the bottom bracket area, so the steering response was always immediate and direct. It afforded the bike a certain poise that could not be perturbed, regardless of the terrain or the amount of energy I was expending.

The Diamante SV Disc was surprisingly smooth and silent. In this regard, the rubber gussett for the seatpost may have had a role to play, because the bike rarely rattled with vibration. Once again, that unshakeable poise was in effect, and it made the bike very easy to ride.

Basso Diamante SV seat tube

With that said, bumps, ruts and cracks all slowly took a toll. On short rides, I was untroubled by the bike’s inability to soak up these kind of hits, and if I chose my route carefully, I could spend three hours on the bike in relative comfort. Beyond that, the effect was much like sitting on an un-cushioned chair: time seems to pass easily until a soreness starts to seep into the body, then no amount of wriggling and re-adjustment can alleviate the discomfort and fatigue.

I spent the majority of the review period using 28C tyres inflated to 60psi, and while there was ample clearance for those tyres in both the frame and fork, I didn’t experiment with larger tyres. A swap to 25C tyres (inflated to 70psi) added a distinct edge to the ride quality of the bike, which really wasn’t needed, so I returned to the 28Cs after just a couple of rides.

The weight of the bike hampered its agility and responsiveness. Rather than lively, the Diamante SV Disc was somewhat dull, even when a set of lighter wheels were fitted to the bike. If Diamante SV Disc wasn’t pitched as a race bike, then the absence of this kind of energy might have been easy to forgive; instead I was left wanting, and my enthusiasm and excitement on the bike suffered because of it.

Basso Diamante SV head tube

With that said, I have no trouble imagining just how effective and satisfying this bike could be for bigger and more powerful riders. I’ve seen these kind of riders really struggle with lighter and less robust bikes; I’ve also seen the way that these kind of bikes can suffer under the load of those riders. In this instance, the effect was the exact opposite, because I was struggling with the bike.

It’s also worth noting that the 56cm frame provided for this review was larger than my ideal size. The low stack of the frame and the 11° stem allowed me to achieve plenty of handlebar drop, but I had to resort to a 100mm stem to achieve my preferred reach. The net result was a noticeable change in weight distribution, which left me feeling like I was perched on top of the bike rather than nestled within.

To my mind, the combination of the two is enough to explain why I had trouble getting the best of the Diamante SV Disc. It was simply too much bike for me.

Basso Diamante SV flat mount disc brakes

One of the things that impressed me about the Diamante that I reviewed in 2013 was the quality of the steering and handling. That bike was supremely stable and encouraged high speeds when descending. As for the Diamante SV Disc, it also had the same kind of handling, and it too, encouraged me to attack tricky descents with more speed.

The steering was close to neutral, which was a good match for the well-mannered poise of the bike. Yes, the bike could run wide out of corners, but rather than fight it, I was happy to give it some extra room and enjoy the speed.

Judging the aerodynamic performance of any bike is always difficult in the real world, but having just finished riding Chapter2’s Rere, which was a noticeably quick bike, I couldn’t help but be underwhelmed by the Diamante SV Disc. It just wasn’t in the same league as the Rere or some of the other bikes that have been proven to shine in this realm, such as Canyon’s Aeroad or Merida’s newest Reacto.

Basso Diamante SV BB86 bottom bracket
Basso makes use of a BB86 shell for the Diamante SV Disc, which is best suited to cranks with 24mm steel axles like SRAM’s GXP.

The Diamante SV Disc was largely trouble-free during the review period, though the thick gloss paint interfered with the fit of the wheel hubs and the flat-mount disc brake callipers. Once the paint started flaking off the inner face of the dropouts, it was easier to install the wheels, but I would have preferred to see these areas masked during painting to avoid the problem altogether. Likewise, the mounting surfaces for the disc callipers, because it made fine adjustments for aligning the brake pads very difficult.

The thru-axles that are supplied with the frameset employ a quick-release lever to ensure a tight hold on the wheels, but it was difficult to judge when to stopping winding the axle and use the lever. More often than not, I had to back off the axle so that the lever could be fully closed. I also noticed that the curve of each lever brought it very close to the rotor once it was closed, so that if it was ever bent, there’s a chance that it might make contact. A thru-axle with a cap head and hex-key fitting would be a better choice.

The seatpost clamp was effective and easy to adjust, but I wasn’t impressed with the small grub screws that were chosen for it. Small hex fittings (and keys, for that matter) are prone to rounding out quickly, and if any of the grub screws ever seizes in the frame — a seeming inevitability given they are located at the rear of the seat tube where road spray collects — they can be nearly impossible to remove. At least it will be an easy matter to apply some tape to protect them from the weather, though most owners are likely to overlook this simple measure.

Basso Diamante SV aero road disc bike

Summary and final thoughts

Basso is obviously proud of the Diamante SV Disc, but when it is compared to what the rest of the aero road bike market has to offer, it falls short of being “the ultimate machine”. It is simply too stiff, heavy, and sluggish to satisfy that claim, especially considering the high-end asking price. That isn’t to say that I think it is over-priced; rather, it is a matter of it being over-pitched to the growing number of riders considering an aerodynamic race bike.

The bike still has some appealing strengths, such as its superb handling and sure-footed poise, along with the potential to satisfy the demands of big, powerful riders that have struggled with under-built frames in the past. This may be a small niche, but I can’t think of many aero road bikes in the current market (Scott’s original Foil is one bike that comes to mind, though) that can match the sturdiness and robustness of the Diamante SV Disc.

What do each of the individual ratings criteria mean? And how did we arrive at the final score? Click here to find out. You can also read more about our review process.

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