Cannondale Slice 5 review

I'm going to do this review a little differently than I typically would. I love the science and technology of time trialing and since aerodynamics and attention to detail are so important to being successful, I have decided to make this a 2 part review with this section focused on the design of the bike and the next part will be dedicated to the ride.

My existing TT bike is a Cervelo P2C which is plenty fast. However, in the past 6 months it has become evident that I can produce significantly more power when I am back in the saddle compared to the tip of the nose position that I used in the wind tunnel and have raced the last couple of years. The problem is that I need more room behind the bottom bracket so traditional stack and reach measurements were not enough to help me make a good decision. To complicate things even more, most manufacturers are building seat posts with at least two positions and they often do not provide effective top tube lengths in every position. Specialized, for example, makes 3 seat posts each with two positions for a total of 6 different seat tube angles. You have to locate a Transition fit guide to get the data on the different geometries, but many big brands don't include it anywhere. Another challenge is that most manufacturers sell the same bike to triathletes and time trialists. The forward position preferred by most triathletes is supposed to help the legs for the run. The back position is referred to as the time trial position, but most TTers seem to slam the saddles forward as well.

I decided that I wanted to try to optimize power and drag and to start I want to use a position that produces maximum power. From there I will work on the aerodynamics in the tunnel and find a good balance as opposed to my mainly aero focused position I am currently racing. I doubt I will keep this frame if I can find a faster frame that has the proper geometry. This frame simply gives me the most options to find the correct geometry.


After considerable research, the Cannondale Slice frame had the most potential for me. It has a 73 degree seat tube angle which is about as slack as it gets in the TT world but more importantly, it also has a shorter reach which is really hard to find. Basically this bike is built for average to short torso riders with average to above average inseams.

I  decided to go with a Slice 5 and simply transfer the parts from my P2. The Slice 2 through 5 framesets are identical. There is a high-mod version which uses a lighter carbon layup, but otherwise the frame shapes and aerodynamics should be the same. Unfortunately, I was unable to look at a Slice before ordering so the first time I saw the frame was when I unpacked it. Upon opening the box I was impressed with the bikes graphics. The red is very bright and I like the graphics package. I then pulled the frame from the box and realized that this thing was an absolute boat anchor. I was not too concerned as the only parts I would be keeping were the frame fork and seatpost and those could not be that heavy could they?

The bike comes in a very small box and with minimal assembly completed. Basically you get the rear brake, both derailleurs, crank and chain installed. That is it, everything else is packed separately. For the average consumer this is not a big deal as the shop will do the assembly, but if I owned a shop I would build a little more assembly time into this bike than a normal TT/Tri bike.

The build kit for my bike is as follows:
Brakes: Shimano Ultegra
Derailleurs: Shimano DA 7800 (ceramic pulleys)
Chain: Shimano DA
BB: F1 Ceramic
Crank: Quarq SRAM S975 53X39 - 175
Cassette: Shimano DA 7800 11X25
Base Bar: HED Vantage 8
Clip-Ons: Bontrager X-Light Carbons
Shifters: Shimano DA 7800 bar end
Front Wheel: HED Stinger 9
Rear Wheel: HED Stinger Disc
Brake Levers: SRAM Carbon
Pedals: Look Keo Sprint
Cables: Nokon
Saddle: Adamo Race
Stem: Oval Concepts Alloy 110mm

The build of the bike is pretty straight forward with a couple of exceptions:

The rear brake mount is contained in a one-piece wheel fairing that does not allow for a traditional fixing bolt. To overcome this Cannondale has a small plastic mount that the brake bolts to and then the mount fits into a recessed section of the fairing via a single 4mm hex bolt. The mount is fairly clever, the only problem I ran into was getting the bolt torque correct where the brake attaches to the mount. The first time I over tightened it and could not get the brake to center, the second time it was a little loose and the brake would drift into the rim. It would have been quicker to fix if I had not needed to pull the entire mount out. The rear chainstays are plenty wide to handle the C2 width HED disc with pretty much any size tire on it so I can't imagine clearance being an issue for any wheel.

As with any decent TT bike, the cable routing is internal. Cannondale does not use behind the stem entry like most of the new generation of bikes, but uses traditional entry points on the top tube and down tubes. The front brake is fork mounted so the cabling there is traditional.

The internal cable stops are where I start to have issues with this frame. The the cable entry points are raised as opposed to flush with the top and down tubes. I really have no idea why Cannondale thinks this would be a good idea. I would assume this is a production issue and reduced the cost, but it is a poor choice for a bike that is supposed to be aerodynamic. Additionally, the holes are drilled out very large. So much so, that my Nokons would not work with them. I had to take apart some old barrel adjusters to shim the hole down enough to get my cables to work. I was expecting to find some kind of plastic stop that would fit into the frames, but they were not included with my bike if they exist.

One thing I did appreciate with the frame is that there are no challenges with snaking the cables through. The bottom of the frame has a large opening and you can feel the cable with your fingers and snag it to pull it through. One thing that does concern me is the way the cable guides are made. The cables touch the bottom of the frame before entering the guides. Since the Nokon cables are closed, it should not matter, but I would not want cables rubbing against the frame. Not only could it cause drag and shifting problems, it might over time dig into the frame.

The seatpost of the Cannondale is a unique design. Switching between the front and back positions is a somewhat involved process. The post is pretty heavy and seems to be more alloy than carbon fiber. The saddle is affixed using a clamp and two long 4mm hex bolts. The most irritating thing about the mount is that as you tighten the bolts it pulls the nose of the saddle up. So you have to guess how far to nose-down the saddle so that when it is fully tightened it will be flat or to your desired position. It took me 3 tries to get the saddle level. The mount design would most likely test very poorly in a wind tunnel compared to.... well, probably any other post on the market I have seen. The reason for that is that the mount hangs out in the wind and would certainly add a few grams of drag. That being said, with a rider on the bike, I'm not sure it would matter that much has his/her legs would probably cover the mount and the air in that area would likely be dirty anyway. One nice thing about the post is that it comes with an inexpensive hydrotail that allows for two water bottles to be placed behind the saddle. The downside is that it only works if you use the front seatpost position. There are other ways to mount some models to the saddle rather than the post, but if you already have a hydrotail it might not work with the Cannondale Slice.

Finally, the seatpost clamp works well, but is not a very aero design. While most companies have integrated their design into the frame, Cannondale basically took a road bike clamp and shaped it to work with the aero post.

The Slice 5 frame gives Cannondale two options for mounting the bottle cages, the down tube and seat tube. Cannondale went with the seat tube option. There are other fast TT bikes out there that also choose this position so I am not singling out Cannondale here, but I do want to say this - STOP IT. If I am racing a TT or Tri I am going to drink from the extensions. I really should not have to reach all the way back  to the seat tube to get my bottle. Also, I simply can't understand why mounts are not placed on each tube. You would not run it in a race most likely, but it would be nice to be able to carry a second bottle on the frame when training. Again, this is not only a Cannondale issue, but in my opinion a problem with every manufacturer that goes that route. Finally, this mounting position will not work with my Specialized aero bottle. I have not tried the profile design bottle yet to see if it is any better, but looking at the area where the bottle meets the down tube, I might just be better off with a round bottle if I chose to race with one.

My issues with the frame to this point are either minor annoyances or questionable designs that could perhaps be refuted. However, here is the deal killer for me on this frame..... Vertical dropouts. I just don't understand why anyone would think it is okay to do this. For those that are not sure what I am talking about I will try to explain. The aerodynamics of the bike/wheel interface will change depending on the gap between the rear wheel and the seat tube. There is some debate over what that distance should be. Cervelo, for example says about a credit card width when racing is correct. I think it was Look who stated that their bike was faster with a gap closer to 1cm. Regardless, of the correct distance the user should have the option to change this distance. Even if the manufacturer were to claim that they produce the bike with the optimum distance designed into the vertical dropout, this would be impacted by different size tires and wheel widths. A HED disc with a C2 profile and a Zipp Sub 9 running the exact same tire will have different circumferences changing the size of the gap. This is unacceptable if you are trying to go as fast as possible on as little energy as possible. While I understand that the Slice 5 is an entry level bike, the Slice 3 & 4 use the same frame. Also, When I look at the Hi-Mod pictures, it would appear their top of the line bike also uses this design. I guess it could be argued that this design might work better for a triathlete who would need to change a tire during a race, but I think any serious triathlete would take issue with this as well.

So at this point you are probably asking yourself why I bought this bike. As I explained at the beginning of the review, I am looking for the perfect bike geometry that will balance power output and aerodynamics. The Slice geometry has the widest range of options for someone with a short torso and long legs. Once I dial in that position, I will then look for the most aero frame that I can use and this will most likely not make the short list. Also, for anyone that is struggling matching their power output on their road bike, you might want to consider moving further behind the BB and this machine allows for that as well as any. I spent a considerable amount of time researching frame options and I must hand it to Cannondale. They are one of the few manufacturers out there that give riders this much choice. I am beginning to feel that I am not alone in having problems producing power in the aggressive forward positions that are dominating TT's and triathlons today. In fact, it took me two years to figure out what is going on and I have to imagine this problem is not isolated to me. I have been helping teammates with their position over the last season and we have changed the starting point. We are creating a position by getting the back end of the bike close to their road bike and then cleaning up the front as much as we can working with what the back-end gives us. Only one teammate has gone to the tunnel after doing this, but we were only able to pick up 11 watts at the tunnel and most of this came from a change in helmets. Meanwhile, his power output is only a couple of percent lower than his road bike.

Another anecdotal piece of information came from the USPro TT last year. I went through the photos that I took and at least half of the riders in the field were using a saddle position that was toward the rear of the available options.

 If you are just getting into Tris or TT's, this bike will be fine for you. At $2,100 retail it is a fair value. However, if you are serious or think you will be getting competitive, you will likely not be happy with this bike in the long-run. For example, the Cervelo P2 complete bike starts at $2,400 with a better parts mix and a frame that I would wager will be way more aero. However, in looking at other options, I would highly recommend considering a bike with a wide range of seat tube angles. If you know you can ride a steep tube without power issues, that is fantastic, but my bet is the average rider may be better off with something slightly less aggressive.

Ride and handling characteristics - I did not have the Slice for a long time. I was injured and knew that this bike was not a long-term solution for me. However, I can provide some feedback regarding the on-road performance of the bike.

The bike was solid in a straight line. The frame and fork do an average job of soaking up road noise and the bike was very stable. I could easily ride it with no-hands which has not been the case with a lot of the TT bikes that I have owned. The bikes cornering was acceptable. These bikes are not meant to have crit like handling characteristics, but I felt confident cornering in the extensions and when I did need to get out, the bike tracked predictably. The bike was relatively stiff. There was definitely some flex in the BB to rear triangle area, but certainly less than the Cervelo P2. I did not have issues with wheel rub and I would characterize stiffness as adequate for a TT/Tri rig. As stated above the bike does an adequate job of absorbing road noise and with the right cockpit and saddle, I feel confident that the bike would work for any length endurance event.

-Tony