Trek Rumblefish Pro Review.

by FatBob on February 25, 2013

The Trek Rumblefish Pro has made the rounds and we can finally give a review. The East Coast trails where we ride (southeast to be specific) offer a wide range of conditions that allowed us to really see what the Rumblefish excelled at and where we felt the bike held us back. Here is what we have found.

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Pedaling: Our local trails require a lot of pedaling, with very little time for recovery. We only have a few climbs in excess of a mile at a time locally, but in the mountains to our west there are plenty of multi-mile climbs for us to test a bike’s abilities on. The Rumblefish is a good pedaling bike, as long as you are comfortable using the CTD lever. Due to its position under the downtube and the lever’s size, it is fairly easy to adjust on the move. During most of our riding it was left in “T” or Trail mode. In Descend the rear end is very active and sensitive to rider input at the pedals. In Trail mode the Trek pedaled very well from the standpoint of suspension movement - this was true in all three rings. Trek’s proprietary DRCV shock is noticeable and, really, this is where it was most valuable. The suspension platform stayed firm feeling on smaller hits and stayed tight for efficient pedalling duties.

The  negative with regards to pedaling and climbing was the weight of the bike. This is especially true of the wheelset. We had the opportunity to run a set of Easton’s EC70 carbon wheels and a set of light Aluminium wheels on the bike and it did wonders for the feel of the bike. Initially, we thought the heavy feel was partially due to an active rear end. However, our experiments showed that it was in the wheelset. The Rumblefish benefits greatly from a light set of tubeless wheels. Even with a wheel change, the Rumblefish Pro weighed 29 pounds 13 ounces with Shimano XT trail pedals and a water bottle cage. The Stock weight with the same pedals and a bottle cage was 30 lbs 10 oz. There is no way around it, the bike is a tank; lots of weight to haul up a hill and even more so for our pedal intensive root infested courses.

Bontrager sells a tubeless conversion kit, which is a quick cheap way to drop some rotating weight and makes a difference in the overall performance of the bike. In my opinion, don't leave the shop without it - try to negotiate the kit into the price of the bike.

Short answer to pedaling, it rides heavy. It is easily fixed by lightening the wheels but still only pedals well not great. There is no way around the weight.

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Climbing: When it comes to climbing, we have to look past the weight to see the Rumblefish’s strengths. It is not a fast climber due to the weight issue outlined above. That said, it does a few things really well as far as climbing goes. The suspension is free to dig into the ground, and increase the capabilities of the 29-3 tires. Bontarger 29-4 tires combined with the Trek’s suspension is tenacious. If you can get past the weight, and are climbing loose terrain, the Rumblefish shines. Beyond its traction abilities is the bike’s ability to steer, and stick the front wheel to the ground. Line changes are easy due to the fast handling and forward weight bias of the Trek G2 geometry. It takes very little weight change to get the Rumblefish to say planted on steep climbs despite the 120mm of front suspension . There is absolutely no need for an adjustable travel front fork. Top billing goes to the Rumbefish’s ability to attack a switchback. The Rumblefish is an excellent bike for riding switch backs. As long as your motor can propel it, the Rumblefish can handle very tight radius switchbacks.

Cornering: The Trek corners well if you learn how to work with the G2 geometry. It did not come naturally to me, but with focusing on subtle weight shifts and trusting the big wheels, the Trek is a very capable cornering bike. The front feels steeper than the numbers read. It responds quickly to input. Initially, this may cause you to over steer. The first few rides I found myself over correcting. I had to learn to relax and not try to muscle the bike. The Rumblefish also feels like it has a forward bias. To corner well, relax your knees, weight dead centered and a little bit of weight on the inside palm pressing down on the grip. With this technique, the Rumblefish corners very well. It needs very little input. Subtlety seems to go a long way.

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The stock Bontrager 29-3 as a front tire does not instill confidence when it comes to a hard leaning corner. Trek sent us a set of Bontrager 29-4 tires. The best setup for a huge variety of terrain was a 29-4 front with a 29-3 rear. The 29-4 in front offers tenacious cornering traction. The 29-3 rear was faster and easy to control as a rear but broke free too soon as a front and, ultimately, held the bike back on all but hard pack trails. If cornering aggressively is your thing, change the front tire to a 29-4 instead of the 29-3. It does come at a cost to pedaling, as the 29-4 is a lot of tire. Confidence in cornering is worth the weight penalty. Few things will send you to the ground faster than a front tire slipping out in a corner.

Descending: Unanimously, the 3 testers felt descending was the Trek’s strongest attribute. The steeper and more rugged, the happier the crew was with the bike. Once you got past the initial firm suspension feel that the DRCV shock causes, the high volume ending stroke is generous and plush. Descending fall line root infested lines was fun on the Rumblefish. Load your weight with a rear bias, and allow the suspension to stay in the high volume section of its stroke. Steering remains precise. Even though the front end feels tight during climbing and cornering, the Rumblefish does not become twitchy on the downhill - no matter how fast we were brave enough to go. It is easy to change lines but it doesn’t get out of control. This lends itself to a great slower speed descender. Think rock gardens where you have to be a little more meticulous about line choice. Threading the needle on the Rumblefish is excellent.
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High speed flow trails were easy to handle at speed but jumping is a bit of an experience. The Rumblefish is a tad front heavy and it requires a hefty pull and weight change to keep the front end up, or to prevent it from prematurely going nose down on a double with a clean pitched landing. The Rumblefish is a little bit more business than play.  One critical problem with jumping the Rumblefish is that the DRCV front fork gets deep into its travel exactly when you don’t want it to, compressing into the face of a jump, or when loading the suspension to loft the front end high. When you add 210 pounds of rider weight, lots of momentum and a steep takeoff, you can feel the DRCV kick in and the fork legs twist. There were many “oh crap” moments in the air and crooked landings. I ended up hitting the jump line of our local trail with the fork in climb mode. This is the fork’s stiffest setting. Even with the fork in climb mode, I experienced the same problem, just a little bit more manageable. I would guess the designers of DRCV suspension didn't design the Fox fork to handle this type of riding. It is worth mentioning because, with modern trail building techniques and flow trails popping up, trail bikes are expected to handle this type of terrain.

Overall if you are riding rocky, rooty, steep down hills with medium size, sheer drops, the Rumblefish easily handles this terrain and inspires confidence.

Components: We have been riding the Rumblefish consistently since November. As a crew, we ride our test bikes a lot. To be sure, this takes time. The benefit is that we can compress the wear and tear on a bike compared to the average rider. The Trek has been ridden every bit as hard as any bike we test and the fork and rear shock are no worse for the wear. Other bikes we have tested we have gone through a recommended hourly maintenance cycle in three months, including blowing seals on rear shocks. The Kashima coating on the fork is a nice value at the Rumblefish Pro’s price point. Other brands seem to cut this feature. The rear shock has the nice upgrade of an easy to feel and operate lever for the Climb, Trail, Descend feature. It is longer and it feels solid, making it harder to accidentally knock out of position.

The full XT kit needs no upgrading. It has been flawless and has required a quarter turn here and there of the barrel adjusters and no more. The XT brakes are an awesome feature. Everyone in the crew is sold on the XT brakes’ performance. Flawless.

The Reverb seat post, as we stated before, is a must have on a bike meant to be ridden like the Rumblefish. For taller riders, a set back would have been nice, as the bike feels small. It is listed as a Large but it feels small. If you are on the fence, size up. A set back would have been great for my 6’2” body. Riders in the 5’9-5’10” range felt comfortable and, to my fitting experience, were the right size for the frame dimensions without having to adjust stem length or setback. Even at that height riders, were sliding the seat back as far as they could on the rails. The infinite adjust is also universally preferred to the mechanically set, 3 position models we have been riding.

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This may sound odd but the stem is super nice. I usually don't comment on this sort of stuff but the Bontrager stem that comes stock is a really nice one.

I believe I would be doing a big disservice to riders looking to buy this bike if I didn't spend time on the wheels. Frankly, they are just too heavy. Going tubeless helps, but still, the wheels ride heavy. In their defense, they are super solid, and I have no question about their durability. With Bontrager’s rim strips and sealant, the tubeless conversion was fast and reliable. Just be aware that the rims are asymmetric and so are the rim stips. This is a proprietary system. I have seen some riders using them on generic carbon rims; if you do this, make sure they are not asymmetrical. With the Bontrager rims, the asymmetrical rim strips work very well. They are a perfect fit and they are easy to install. Still, the wheels are heavy. The wheels exaggerate the overall weight of the bike, and make it feel slow. At first, I thought maybe the active rear suspension was adding to the feeling. Usually when the rear wheel is free to act with little chain stretch, bikes don't have the lively feeling at the pedals that bikes do when this is not an issue. To determine what was going on I started changing wheels, tires, cassettes and going through suspension settings in an effort to isolate the sensation’s source. Immediately after we switched to a light wheelset, even using the stock tires, there was a dramatic difference in how the bike felt. The scale did not show the dramatic change (carbon wheels took the bike down to 29 LBS 13 oz with everything stock, Shimano XT trail pedals and a bottle cage). Even so, the acceleration was vastly better. Even the handling felt more lively. After the carbon wheels, I went to a lighter alloy wheelset. Similar results. The good news is that the suspension has no adverse affects on the bike’s acceleration. Bad news; the frame has to be fairly heavy and, to get the most out of the Rumblefish, you have to buy new wheels. Again, I’ll go back to defending the Trek. the wheels are strong and show the purpose of the Rumblefish, plow through everything in your path ! They are strong and have been very durable.

Overall, the Trek Rumblefish Pro leaves very little to be desired in the parts department. Nothing needs to be upgraded and I would say, over the years of owning the bike, there is little need to look for places to upgrade and nothing besides a tubeless conversion that has to be done immediately.

Who should buy this bike ?

Bomb proof reliability from head to toe. The RumbleFish is overbuilt. This should equal a long term investment. Besides lightening up the wheels, there is nothing to upgrade. Everything on the bike is really worthy. Even the wheels are strong, roll well and feel responsive to ratcheting pedals in technical terrain. If the weight doesn't bother you, the stiffness and durability will please you. If you live in rocky terrain with steep loose descents the RumbleFish is great. If you climb steep terrain and value steering precision and like to get a great work out, the RumbleFish delivers. Lastly, the RumbleFish rider needs to like feeling the ground under them. This is the real strength of DRCV suspension. You feel what's under you. It doesn't feel like its doing the work for you. But when you need a bail out, the DRCV kicks in and offers plenty of cushion and forgiveness.