ROAD TEST: VENTUM
The new Ventum design harks back to a time when one of the fastest bikes was built up from washing machine parts, the Superman position was favoured and the Lotus ruled supreme. Yes folks I’m talking about the uber sleek Lotus 108 TT machine that saw Chris Boardman blow the hour record out off the water, as opposed to the sea diving submarine/car version of James Bond in ‘The Spy Who Loved Me’.
Not surprisingly you can guess that the Ventum has taken many design cues from the Lotus 108’s successor the 110. While the unique hydration system is inspired by F16 and F18 fighter aircrafts conformal tanks to provide an integrated fluid reservoir supposedly providing the lowest possible drag numbers under racing conditions. A future integrated aero bento box is in proto-typing stages and should be ready early 2016, which will fill the gap between the head-tube and the reservoir. The rear gear shrouding was yet another focus that impressed which most other bike manufacturers don’t seem to pay as much attention to. And of course the bike needs to be as adjustable as possible to get the majority of fit positions catered for.
The bike will also feature a new fork and fairing was designed to lower the drag on the leading edge of the bike. This is a very important drag point on the bike where turbulence is created by the front wheel, causing a thin boundary layer of air sticking to the surface of the wheels and tire. The new front fairing and fork combo is said to shave 6% off frontal drag due to its unique shape. It’s been designed help clean up the interaction between the conflicting wind directions, caused by the rotating front wheel dragging air forward and the frontal wind travelling backwards along the forward moving bike.
One very noticeable aspect of the bike appears in the asymmetric rear chain stays. According to Ventum, they are designed like that for a few reasons. By protecting laminar air flow over the rear of the bike by shrouding the rear cassette and derailleur which reduces overall drag. To achieve this, the drive side chain stay is very wide and this also helps make the arm very stiff horizontally. The non-drive side is very skinny and tall, allowing the wind to stay attached to the frame from the leading edge of the seat tube through to the rear skewer. The left chain stay also is very stiff vertically. Once the rear wheel is installed, it ties the two sides together, resulting in the bike being well balanced, giving the rider a lot of confidence cornering, descending and climbing.
We usually don’t get too much detail on the development and testing of a completely new bike but Ventum have given us a run-down of the process they went through, which we thought we’d share. The first and most important task was to develop a CAD solid model that was created and continuously refined to find there most aero shape. Once they had confirmed the final shape, they ran stress analysis using FEA (Finite Element Analysis). These results showed them how to design the carbon fibre bias, direction and thickness.
Ventum aimed to maintain a section modulus appropriate to the structural loads experienced at any point of the frame. This was achieved by carefully blending the frame shape and form to reach the correct section modulus at all points of the frame. This resulted in a frame that is able to handle stresses and loads placed on the bike throughout the whole load envelope.
Structural testing was divided into three categories including “load – deflection” testing, “impact testing” and lastly “fatigue testing”, where over 1 million tests cycles where completed on all four of their frames which is much more load cycles than ISO testing requires.
Aerodynamic testing was conducted in 2 different wind tunnels; Faster and A2. The bike was tested with rider on and off with a range of wheels. The bike design was refined in the wind tunnel for the real world. Road testing by World Class Professional athletes from triathlon and cycling, which brings us to our test.
Our test bike, being a prototype, was a little different to what the first production models will feature. We had an off the shelf fork, stem and integrated brake system which as we referred to above will change, as well as the stem/bar combo being upgraded to a slightly new design allowing even an greater range of fit options.
A full Ultegra Di2 running system ordained our rig including a set of Ultegra training wheels. This groupset is our best option for those chasing value for money, while also providing flawless gear changes. Ventum stocked the bike with an ISM prologue saddle, a fine seat in its own right, however due to comfort we swapped it out for own preference in an Arione Tri2. We were concurrently testing some deep carbon clincher wheels that also got a workout to test the bike under closer race type conditions.
Once built all of the fit was a piece of cake. A single Allen key bolt, recessed in front of the seat post was all that was needed to adjust seat height. Likewise the saddle position was equally easy to work with, giving more than enough fore/aft as well as tilt adjustment. One thing we did note was that an Arione Tri carbon braided saddle wouldn’t fit on the seat clamp, resulting in us using the kirium railed version.
Moving to the front end, we found adjustment of the pad height and width was pretty straight forward, again with the Allen keys. That being said there wasn’t much we needed to change other that moving the arm rests a little wider apart and further back. We also moved the extension length a little further forward and with the stock extensions we still had plenty more length to play with. Due to the nature of the integrated stem and base bar combo, height adjustment of the pursuit bar wasn’t possible, meaning those less flexible may struggle a little finding a comfy position when braking. Hopefully the new version of the base bar will allow a greater range of rider fits to be accommodated. The stock extensions were a gentle ski bend which we both prefer to any other design. At about 20 degrees at least one of us thought this optimal, while the other prefers around a 40 degree tilt. These being 22.2mm in diameter means they can be easily swapped out if desired.
As referred to earlier, we changed the wheels out for some of the testing to deep carbon rims. This was a little frustrating adjusting the brakes to accommodate the larger rim width as the bolt that controlled the front caliper release had a Torx interface, which took a lot of time to work out. Hopefully the full production model rectifies this to the standard hex interface. The rear wheel was a lot easier to work on with a standard 4mm Allen key doing the job.
The unique fluid reservoir was pretty easy to take off to clean and re-install. One thing we did find was the bolt and clamp system that attached the reservoir to the bike needed to be very tight to avoid the bottle rattling over bumps. The screw that tightened to the clamps was very difficult to move once firm, so we might expect this design is changed to something cleaner and more user friendly in future models.
Our bike was a size 54cm which for us having virtually identical front end stack and reach suited us perfectly. The seat angle range of 75-79 degrees gave use ample space to have the tip of the saddle just at the bottom bracket with room either side.
Next we looked at the ride of the Ventum. Usually both of us ride the bike, compare notes and put pen to paper. But with the Ventum being a bike with a few unique idiosyncrasies, we haven’t come across with other bikes, we thought it would be interesting to share both our experiences of riding the Ventum.
Ride quality – Craig
Once I was satisfied with the position, I kitted up to hit the road. When we test our equipment, we try not to bias each other before each has had a least a bit of time to evaluate the feel for ourselves. I got hold of the bike after Pat, but he found it tough not to tell me how unique the ride quality was and therefore I had some pretty high expectations off the bat. I usually don’t like to judge the quality of the ride on a first outing as I find I like to make small adjustments, but there was an immediate feeling that I was ready to ride hard.
Using my standard out and back course that has a variety of ups/downs, turns and flats I noted this bike was special. From the moment I put pressure on the pedals I could feel how efficient the power transfer was. On the flat the bike is THE BEST time trial machine that I have ever ridden, period. I attribute this feeling to the massive amount of carbon fibre in the bottom bracket and chain stays, giving the bike an unparalleled level of stiffness. While difficult to verify without some tunnel time, I tend to agree with the manufacturers claims of the most wind cheating bike on the market today. The attention Ventum have paid to the shape of the tubes around the stays and the enormous top tube maximise the best of both aero and strength. Interestingly the off the shelf fork set is clearly no aero slouch in its own right, making me wonder how much better the next iteration will be.
Given the vastness of the carbon frame, one would assume the bike wasn’t a lightweight. This is correct with the prototype frame we had, however the production model, which uses a different manufacturing process will be a few hundred grams lighter, bring it closer in line with other ‘Super Bikes’ in the marketplace. I thought this may affect the ability to climb but my own excess poundage far outweighs any slight increase in bike weight. I will admit that I never rode any long steep climbs but on those uphill sections that were ridden I found no great issue with weight. I believe the efficiency of the frame in delivering power to the drivetrain may offset any extra wattage needed to push forward. I was asked by some friends who I spoke with on the matter whether or not I’d choose to ride this bike on a super hilly course in light of the weight? My answer was that apart from the odd European race in the Alps there are no courses hilly enough to warrant any change. This is after all, a pure triathlon bred machine so there will be no individual TT being done either.
Going downhill was unremarkable, with good (not great) braking making me feel confident to ride hard through descents. Until these bikes are fitted with disc brakes I don’t assume I’ll ever be able to brake with the surety of most road bikes, nor do I think I need to. Again referring to the assumption above that no course locally will require a super agile bike for the downhill portion of a race.
Cornering was one area that this bike wasn’t as stellar as some others. While it isn’t bad going around 180 degree turns, the higher centre of gravity caused by the 1.5 litre fluid reservoir, does make it less nimble, especially on tight turns. It does have a noticeably different feel initially when climbing out of the saddle or going through a U-turn. After a few weeks on the bike I was more than used to the feel.
The hydration system worked about as well as expected. I’m not really of fan of the bite valves as they don’t seem to deliver as much fluid as I would like for the effort. I didn’t try to drain the bottle during a ride but got pretty close, and still found that the straw worked equally as well near the lower fluid levels as it did the top. Refilling was actually very easy with the soft rubber plug being fairly easy to manipulate. It should be noted that this wasn’t tried under the stresses of a race, but with practice should be no more difficult than any other similar set up.
Overall, I rate this bike as one of the best triathlon bikes I’ve had the pleasure of riding. The bike performs well under all conditions, but really excels on the flat to mildly bumpy terrain, where I think it’s in a class all on its own. I still don’t think it’s as beautiful as some other TT bikes but when performance is the measure of the day, looks just don’t matter. I’m really looking forward to seeing the production model, especially if the front end is a little more adjustable and it comes up a touch lighter on the scales.
Ride quality – Patrick
Being about 4cm shorter than Craig, but with the same stack and reach, means that we comfortably ride the same sized bike. Just drop the seat height. My first ride experience of the Ventum was literally jumping on it right out of my garage. And even prior to getting the position dialled right in this bike felt fast! At first sight you immediately think ‘without the aid of a down tube is this thing going to be like wet spaghetti’? Well the answer is a resounding no. In fact for me it was the stiffest ride I can remember. I found myself getting up to speed in record time and able to put the power down out of corners with ease. As Craig mentioned, the sheer volume of carbon in and around the bottom bracket coupled with the very stiff and beefy, but unique, rear stays makes it feel as if every bit of power you put into the pedals is being transferred into propelling you forward. What amazed me the most was when testing the Ventum in high wind conditions there seemed to be very little push from cross winds considering just how much carbon and hydration there was for the wind to hit. Just on a side note, the bike actually felt even more stable when you added a set of deep dish wheels. Seriously in ‘race’ set up this bike is an absolute rocket!
Now I ride with my knees coming in so I will say that I found the integrated hydration system to be a bit of a nuisance to begin with. I kept banging my knees against the plastic reservoir. But by the second week I had that under control, all it really meant was a slight adjustment to the way I ride, I never really noticed when it became a natural feel. What I did need to concentrate on though, was cornering. With the weight of the bike being so high, and especially when riding with a full ‘tank’, I really did need to adjust how I position my body on the bike when going through a corner. I felt a bit skittish in the beginning and it was probably a good week before I felt comfortable going through any sharp or descending corners, at any speed. Once I got used to the different centre of gravity of the Ventum I actually found it to be quite zippy through corners. Maybe not as quick as the Cannondale Slice we reviewed earlier in the year, but not far off. Interestingly I found the bike to climb extremely well. I wasn’t expecting it to feel so spritely up the hills with all the extra weight of the additional carbon, but it climbed like a much lighter bike. Also of note was just how compliant the bike felt on harsh country roads. For such a stiff bike with a significant amount of carbon I would have expected a lot of road chatter, but again the Ventum surprised and gave a very plush ride.
Like Craig I also found the Hydration system a breeze to refill, although I didn’t get the chance to test under race conditions. However what I would love to see in future versions is a cap flat against the tank instead of sticking up in the wind. It may only be aesthetics but it would add to the overall sleekness of the bike. Add to that the future bento box to fill the void between hydration and stem and hopefully some cunning spares storage and you will have the ultimate triathlon bike, along with what feels like the fastest.
I really think once the Ventum hits full production you are going to see a lot of them at a race near you, but maybe not for long as there is a good chance they will disappear up the road ahead of you. One thing you can count on though is the Ventum is here to stay.