Ken Hutchison, Editor-in-Chief

Wheeled Science

A large Fed-Ex box arrived in the office the other day. This was the final piece of the puzzle, the coup de grace for our CBR600RR Project Bike. The other editors in the office gathered around as the box was opened. We waited with bated breath as the gift inside was unveiled: A gleaming black carbon fiber rear wheel with machined aluminum hub shone brightly in the glow of our florescent office lights. The translucent carbon resin has thousands of fibers aligned perfectly, forming the most magnificent black, five-spoke wheel any of us had ever seen.

“What is that?” asked our office intern in a cowed tone with his eyes bulging. He slowly extended his trembling hand to touch it like it was the Holy Grail. His hand is slapped away. We explain that this is the single sickest piece of unobtanium you can procure for a motorcycle and that he was not allowed to ever, ever touch them. He skulks away, casting a cold stare over his shoulder while the rest of us close into a defensive circle, reveling in their technological beauty.

All joking aside, that is sort of how it went down. The $3750 carbon fiber BST wheels are about the most stunning aftermarket components I’ve ever seen on a motorcycle, this side of our pin-up calendar girls. We had them bolted onto our 2010 Honda CBR600RR Modified Supersport project bike and were chomping the bit to find out what you get for selling your soul to hang these ornaments on your ride. So, we strapped our trusty V-Box data acquisition system to the front of the CBR and burned a few knee pucks across the apexes of our favorite road course, Thunderhill Raceway in Willows, Ca.

Before we hit the track, here’s a look at the BST carbon fiber wheels we would be evaluating. They are are manufactured in South Africa under the name Blackstone Tek since 2002 and have sold over 10,000 wheels in under a decade. Here in the US of A they ‘re distributed by Brock’s Performance. They feature CNC-machined billet aluminum carriers and are offered with steel bearings for $3750 a set or ceramic bearing for $4000. The front wheel weighs in at 6.1 pounds without rotors and 12.1 pounds with rotors while the rear is 8.2 pounds, but that increases to 10.1 pounds with the sprocket hub attached. Keep in mind the new generation CBR600RR OEM wheels are lighter than most other supersport bikes. The Honda front is 14.1 pounds with rotors while the rear is 13 pounds with the brake disc but without the 4.5- pound sprocket and cush drive. Using the Honda meant that the BST wheels would be compared against the lightest OEM wheels we could muster up, which should make any measureable performance gain that much more impressive.

We are comfortable and familiar with the Pirelli Diablo Supercorsa so we chose them for our baseline rubber to keep the playing field level during our Shift Racing track day the test was soon under way. T-Hill usually has decent grip, although on this day, temperatures were a little nippy and grip wasn’t at a premium. Since we were conducting this test at a track day we were not able to get a clean lap every time we circulated the track. After taking turns for a session on each bike to scrub in the tires and get familiarized with how they felt, we sent Road Test Editor Adam Waheed on course with the job of turning a dozen laps with each set of wheels so we could get good, usable data for our review. Heed took note as to which laps were the cleanest and combined the best three so that lap times, section splits and general data was averaged out and not just an anomaly. Adam is a steady, consistent rider who is familiar with T-Hill and has a good feel for what the motorcycle is doing. When he came back from his first session on the BST wheels he proclaimed that they made a huge difference in all aspects of the bikes performance.

“Compared to the stock wheels the BST wheels made a dramatic change in the bikes handling,” explains Waheed. “It changed directions from side-to-side so much faster that it actually took a bit of time for me to acclimate to how quick it steered into the corners.”

Our assumption is that they should decrease the time and effort it takes to hustle a motorcycle through a technical section like the Turn 3 through Turn 5A segment at Thunderhill and that’s exactly the case. Data analysis revealed that the average time through this section on the CBR with OEM wheels was 18.31 seconds. With the BST wheels the average time was 17.74 seconds, a half second quicker. This is a significant amount of time which was supported by the indicated trap speeds through the two short sections of track connecting these turns. A key to the faster time has to be attributed to the quicker transitions and acceleration. Turn in feels much more immediate and a little extra jump off the corner doesn’t hurt either. Our average top speed between Turn 3 and Turn 4 was 69.13 mph on the OEM wheels and 73.24 mph with the carbon fiber wheels. Between Turn 4 and Turn 5 the OEM top speed was 77.45 mph compared to 82.56 mph with the BST. Apex speed was also higher through T4 and T5 on with the BST as well.

Taking a look at the section as a whole, you enter Turn 3 going slightly downhill on the brakes scrubbing off 90-95 mph into an off-camber 60-mph right-hand turn. It’s a sketchy entrance to a section of four turns that includes the technical “Cyclone” aka Turn 5 & 5A that shoots you uphill into Turn 5 over a blind 45 mph left at the crest. As you drag your knee over the curb the track drops away steeply as you plummet downhill that is all a part of the same sweeping off camber right hander known as Turn 5A. It is exciting and there’s nothing that can challenge a bike’s flickability on this track like this sequence. The rider muscles the back from side to side, accelerating, trail-braking and shifting without a reprieve for close to 20 seconds.

If the review was based on this section alone we would say the BST carbon fiber wheels make a huge difference but as we dig deeper into the data there are a few areas that they didn’t hold such a clear advantage. On the ultra-fast back straight that starts on the exit of Turn 6 and continues through Turn 7 and Turn 8 the OEM and BST wheels were neck and neck. The limiting factor for the BST wheels here was a more flighty, somewhat less stable feeling from the front end as we rocked through this sequence at 115 mph while dragging your leg if you’re so inclined to hang off that far. It would take a bit of time to dial in the fork to offset the reduced un-sprung weight of the carbon fiber wheels but we did not have the time to make that happen. As it was, the split times revealed the OEM wheels averaged a 0.25 second advantage through a section that takes 21-22 seconds to navigate. This is a section that puts a premium on the rider’s ability to get a good drive out of Turn 6 so any lapped traffic could skew the results of a lap time, but remember that is why we ran this data as an average and not base it on a single fast lap. Although it is a small gain, the noticeable stability of the bike and OEM wheels during extended high-speed maneuvering just cannot go unmentioned.

For that matter we are brought back down to earth a bit by the data from the Turn 10 through Turn 13 segment as well. With the OEM wheels we averaged 14.74 seconds compared to 14.67 with the BST. It’s a scant amount of time that was offset by the average exit speed at the end of the section at Turn 12 where the OEM wheels recorded 81.17 mph compared to 80.82 mph for the BST. Then there’s the top speed between Turn 10 and Turn 11 where the OEM edge out the BST 80.48 to 80.47mph. For pundits looking for ammo to discount the benefit of the lighter carbon wheels, the argument ends right here.

From the exit of Turn 13 all the way to Start-Finish the BST wheels accelerate faster. Starting with a one mph advantage out of T13 the BST gain three mph on the OEM wheels on the straight leading to Turn 14. It is the initial drive out that for a couple hundred feet that the gain is made then the speeds stay parallel at 126 mph for the OEM and 129 mph for the BST. At the end of the front straight there is less of a difference with an average top speed of 137.72 mph for the OEM and 139.06 mph with the BST wheels. Again, the advantage occurs in the first couple seconds, then the difference is maintained the length of the straight. When you add up all the slight advantages over the course of a lap you can see how it is easy to decrease lap times by a second or more with the addition of the lighter wheels. But acceleration and handling are not the only areas that improve.

One of the bigger surprises came when the data revealed that braking performance showed significant gains. Remember that the Modified Honda CBR600RR had aftermarket brakes from the start so this is a good apples–to-apples comparison. Speed was shed more quickly in the first couple seconds of hard braking with the BST wheels than the stock wheels. From 120 mph the carbon fiber units shortened the distance it took to get to 60 mph by an average of 97 feet. Can anyone see a benefit to out-braking another rider into a turn?

“I noticed an improvement in terms of braking with a reduced amount of lever input required to get the machine to slow down,” confirms Waheed. “In terms of acceleration the bike didn’t feel like it accelerated much harder but considering how much of a difference it made in side-to-side handling and braking I assume that the wheels do contribute to faster acceleration.”

The question you have to ask is will a set of BST carbon fiber wheels help me? It depends on what you are trying to accomplish. When it is all said and done the faster riders stand to get the most from lighter wheels. These are the folks looking to shave a few extra tenths off their lap times here and there. Club racers in particular would stand to benefit from a little bit more acceleration and the reduced effort associated with maneuvering the motorcycle at race speeds. It’s a cumulative effect. They should in theory, save a little energy throughout the process. Fast riders will also be able to dial-in their motorcycle suspension and chassis better than the average rider so they will be able to exploit the benefits of lighter wheels. The wheels turn in quicker so riders may not need to drop the front end so low. This can then allow for the front end to be set up higher and reward the rider with the best of both worlds so the bike turns in quick while remaining stable. We mentioned earlier that this will take a little effort to get the chassis sorted but would be well worth it in the end.

By contrast you have the track day or regular street riders. Their performance gains they will be more pronounced and the expense could be easier to justify. Imagine shedding a second or two off your lap times by swapping wheels? Imagine gaining a couple mph on the straight and a few tenths here and there without much effort? No doubt it seems great in theory so here are a few pros and cons to keep in mind.

First of all, when choosing performance enhancing products like tires, exhaust, brakes, engine work or in this case, wheels: There is always a price to be paid and usually a sacrifice as well. Sticky tires offer more grip but are expensive and don’t last as long. Exhausts look and sound bad-ass, shed some weight and give usually a 10% increase in horsepower, but there is usually a slight sacrifice in bottom- or top-end power, plus these days they can bring the heat down on you too. New rotors, braided lines and top-shelf calipers are a no-nonsense way to take your braking system to the next level. Cost is the biggest factor here, otherwise there’s not a lot of downside unless you screw something up on install. So let’s look at the pros and cons of the lighter wheels. A relatively straight forward and simple upgrade requires new sprockets too. The bike will be quicker, more agile and braking performance will increase. Plus, the motorcycle will look like a factory machine with all that gorgeous carbon fiber.

Do you get $4000 worth of performance out of a set of BST wheels? We believe the data supports an argument for the value of lighter wheels. There are instances where the OEM wheels are on par with the BST units but the majority of the time the carbon fiber hoops provide a legitimate performance increase in key areas. They receive the MotorcycleUSA Road Test Editor Adam Waheed’s stamp of approval so what more do you need?