String Face-off: RPM Blast vs. Champion's Choice Duo

by: Tennis Warehouse | February 04, 2019

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Roger Federer or Rafael Nadal? Who is the Greatest Of All Time (GOAT)? Roger has more Grand Slams, but Rafa owns the head to head. Federer is the oldest player to capture the world No. 1, but Rafa has more Masters 1000 titles. Both players have tennis résumés to die for, but each has taken a different path to glory. Roger has chosen a classic player's racquet strung with a mix of Wilson Natural Gut and Luxilon ALU Power Rough, which is aptly called Champion's Choice. Rafa went with a modern player's racquet strung with a spin-friendly, extruded co-polyester that's fittingly named RPM Blast.

With the Roger and Rafa rivalry showing no signs of abating, we dive into the details. Here we zero in on the players' stringbeds by pitting Wilson Champion's Choice Duo against Babolat RPM Blast.

Could one of these string choices be the key to ultimate GOAT status? Read on to find out.


"How a string plays comes down to one basic thing: how stiff it is."
—Crawford Lindsey, co-author "Physics and the Technology of Tennis"

Although there are many variables that determine how a string feels and plays, none is more important than stiffness. A string's stiffness level not only impacts how fast, high and far a ball will fly when struck (power and control), but it also influences the type of feedback and the amount of shock that reaches your arm (feel and comfort).

Nadal's RPM Blast is categorically stiffer than Federer's Champion's Choice. This is because RPM Blast has an extremely firm monofilament construction, while Champion's Choice is composed partly of natural gut, which is the softest and most elastic string type available. The on-court payoff of Champion's Choice was easier access to power and higher comfort. The downside was less control, which is the category where RPM Blast truly shone. As a full-bed polyester player, Chris loved the firm feel and controlled response of RPM Blast. The challenge for him was figuring out the correct reference tension for Champion's Choice. He said, "From the first hit of the test to the last, I was fascinated by the differences of RPM Blast and Champion's Choice. I'm very familiar with RPM Blast, so I had it installed at 50 lbs in my Tecnifibre TFlash 300 PS and was good to go. At that tension, I was getting a great blend of power and control. I know from previous tests with this string that I can go down to 48 lbs and still get ample control. RPM Blast is a low-powered string, and I love how it pairs with my powerful racquet. I can get all the power I need, yet I have so much control from the stringbed that I don't have to hold back and can swing freely. My first outing with Champion's Choice was also at 50 lbs because I wanted to feel only the differences between the strings and not have to guess if the tension was affecting anything. The result was too much power. The natural gut main string pocketed the ball very well, and I was getting excellent power. To add control I had the next set installed at 57 lbs with a pre-stretch on the gut. The result was a too-firm feel that lacked power but was somehow still comfortable. My third stringing was right in between with a pre-stretch on the gut, and it felt great. Champion's Choice wins for comfort and power, but it took me some time to get it dialed in and closer to the control level of RPM Blast."

Like Chris, Troy immediately noticed the different stiffness levels between RPM Blast and Champion's Choice. As a result, the winner for power, control and comfort was obvious. He explained, "RPM Blast is clearly the stiffer string. When strung at the same tension, the difference in power, control and comfort was easy to distinguish. The softer, more elastic Champion's Choice provided a noticeable zip off the stringbed, with more power available for hitting through the court and more free power on serves. It also offered more pop on volleys. The winner for control was the stiffer RPM Blast 15L, which allowed me to swing as big as I wanted. From all areas of the court, it was a point-and-shoot weapon. When hitting flatter groundstrokes, RPM Blast felt much deader than Champion's Choice — not in a bad way, but in the sense that I could swing out without fear of overhitting. Control with Champion's Choice wasn't bad, though, especially after I raised the tension. As for comfort, the soft natural gut mains made Champion's Choice the obvious winner. No matter how tightly I strung this hybrid, it felt comfortable. There were times when I was hitting groundstrokes with Michelle, who hits a very heavy and flat ball, that the level of shock absorption from Champion's Choice was unreal.


Jim Courier achieved respectable levels of spin from synthetic gut, and Rafael Nadal could probably get heavy ball rotation from fishing line. This is because spin comes mostly from technique, specifically the racquet's tip speed and angle of attack. That said, both RPM Blast and Champion's Choice have features that make hitting spin a little easier. In fact, Troy had a hard time deciding which of these strings had better access to spin. He said, "When it came to spin potential, this was a surprisingly close battle. Based on TW University lab results, I knew that a hybrid with natural gut mains and co-poly crosses could yield a lot of spin. I experienced this high spin potential from Champion's Choice. When I took a big rip from the baseline, my shots were kicking up high off the court. The downside was whenever I had to attack a short ball that landed near the service line; I found it difficult to grab the ball and get it to dip over the net. On acute-angle topspin shots, I found the RPM Blast much more reliable when I needed to bend the trajectory with a quick flick. RPM Blast had great spin in almost every circumstance, while Champion's Choice's spin was more situational. RPM Blast gripped the ball better than Champion's Choice on strokes when I had to slow down the racquet head a bit, and when I was able to take a full swing, RPM Blast performed just as well."

"Both stringbeds offered me a lot of spin," said Chris, who had an even harder time picking a winner than Troy. "We've tested RPM Blast many times, so I knew going in that I'd be getting a lot of spin with it in my racquet. The kind of spin I get with RPM Blast is comical at times. I can get away with shots that should land out, but the amount of bite from RPM Blast gets the ball to dip just inside the lines. The amount of topspin I can get from it instills the confidence to stay on the gas and swing big — it's one of the main reasons why I love RPM Blast. I was equally impressed that Champion's Choice went toe to toe with RPM Blast when it came to spin. I loved the way Champion's Choice pocketed the ball and spat it out with spin. It was my favorite of the two when it came to hitting my backhand slice. I was reveling in the dirty, low-skidding slice I could produce with it. I also had great feel on my slice shots and felt confident knifing them to my targets. Likewise, whenever I wanted to roll a topspin lob or an angle, Champion's Choice kept me in touch with how much spin I was getting on the ball, which made it easier to control depth and placement."


Unlike stiffness or gauge, there is no easy way to measure a string's feel, especially since it includes a subjective element, namely the way a player experiences both the force and response of ball impact. Having said that, the category of feel is impossible to ignore because it is often crucial to why a player prefers one string over another.

Our playtesters found a noticeable difference in feel between the firm RPM Blast and the softer Champion's Choice Duo. In addition to explaining how that difference translates to the court, Chris helps us understand the way reference tension and pre-stretching impact feel. He explained, "Another really interesting part of this playtest was the difference in feel between the two stringbeds. My inner product-testing nerd was in overdrive, exploring what I could do to alter the feel of Champion's Choice. Strung tightly with pre-stretched mains, it delivered a very crisp, firm feel and a low trajectory, yet it still cupped the ball and felt comfortable. At a low tension, the stringbed felt very plush and lively. The launch angle was higher, and I was hitting a loopier ball. With the mains around 55 lbs and the ALU Power Rough crosses at 53 lbs, I found the feel I liked. I was getting enough crispness from the stringbed, the pocketing was superb, and I felt totally dialed in on my touch shots. RPM Blast offered a more muted feel. I've always been a big fan of its firm, low-powered response. When strung at a lowish tension, RPM Blast allows for some nice pocketing and plays more forgiving, yet it gives up absolutely nothing in terms of control."

Like Chris, Troy also noticed big differences in feel, along with recognizing the importance of getting the reference tension right. He described, "Being that I primarily play with a full bed of co-poly, the firm feel and controlled response of RPM Blast is very familiar. It plays great for me at 47 lbs. If I go higher, it becomes a little too stiff and dead, and if I go lower, the high tension loss makes it feel mushy too quickly. Given that I am less familiar with Champion's Choice, I had to do some troubleshooting. When I first started hitting it, the amount of elasticity, vibration dampening and pocketing from the natural gut mains was unique and a bit foreign to me. Champion's Choice felt extremely comfortable compared to RPM Blast, but it was also a little too lively and harder to trust on full swings. I needed to string it 5 lbs higher to get the right amount of control. Once I had the tension right, I actually preferred the crisp and responsive feel of Champion's Choice over the deader and more muted response of RPM Blast."

Tension Maintenance/Playability Duration

Let's not mince words. Champion's Choice Duo has better tension maintenance than RPM Blast. This is because it includes natural gut, which holds tension longer than any other material or construction type. The upshot for our crew was that Champion's Choice retained its playing properties longer than RPM Blast, which we found to have poor tension maintenance. Troy explained, "This was another category with a clear-cut winner. Champion's Choice was my pick for playability duration. Even when compared to other co-poly strings, I found RPM Blast to bag out and lose tension relatively fast. Some examples of co-poly strings that I find to hold up longer are Solinco Hyper-G, Solinco Tour Bite, Luxilon 4G, Signum Pro Poly Plasma and Tecnifibre Pro Red Code Wax. On a positive note, the significant tension loss didn't necessarily cause the RPM Blast to play badly, it just felt bagged out and unresponsive. With the Champion's Choice Hybrid, the tension was very consistent throughout the test period. I noticed somewhat of a settling in period. Off the stringing machine, the tension felt somewhat firm at 52 pounds. During the second and third hitting sessions I could tell that the string sort of hit its sweetspot, and from then on I didn't have any issues with the tension or feel. If anything, the Luxilon ALU Rough was the aspect of the hybrid that I might switch out for something like Luxilon 4G 16L for maximum tension hold."

"When it came to how well the strings held up in my racquet, this was a non-contest," said Chris, who had no problem figuring out which string stayed playable longer. "As much as I love RPM Blast, like most poly-based strings it simply does not hold tension very well. On the flip side, I actually preferred the playability of Champion's Choice after it had settled in my racquets. I found the playability of the stringbed to be so dominated by the gut main strings that even though the cross strings lost some tension, it didn't alter the playability very much. As the test wore on, I got more control from the Champion's Choice and less control from RPM Blast. Since my favorite quality of RPM Blast is control, it is a string I like to keep fresh in my racquets."

Overall Winner

Deciding between Federer's Champion's Choice Duo and Nadal's RPM Blast was no easy task. With its "best of class" levels of control and spin, RPM Blast is the archetypal co-poly. It was built to unlock the explosive mechanics and malicious angles upon which the modern tennis game is built. On the other hand, how can you argue with the power and feel of Champion's Choice Duo? Granted, it has a hefty price tag, but it stays playable much longer than RPM Blast, and it delivers better touch and responsiveness on shorter strokes and volleys. For Chris, however, the string with the most control and spin emerged victorious. He described, "Even though I grew to enjoy Champion's Choice more and more as the test wore on, I couldn't get away from how much I love a fresh set of RPM Blast in my racquets. The amount of control and spin I get on the ball with RPM Blast is addictive. While there will always be times when I overhit or the ball flies on me, there are less of those times when RPM Blast is in my racquet—and that is why it is my winner for this comparison."

As a full-bed poly player, Troy loved the control and spin he got from RPM Blast. However, in the end, Champion's Choice was simply better across more categories. He explained, "In this battle of two of the most reputable strings on the market, it was a close fight. As in a lot of boxing matches, the fight was closer than the scorecards might indicate. The string that was the most familiar to me at the beginning of this fight became worn down in the later rounds and lost its momentum. So the winner by a score of four performance categories to one, and still the 'heavyweight champion of the world' is Wilson Champion's Choice Hybrid!"

Despite our testers being split on which string they preferred, you can find out which one is perfect for you by asking:
Do I want excellent control and spin (RPM Blast) or lasting playability, comfort and power (Champion's Choice)?

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