Trek Speed Concept 2.5

The Speed Concept 2.5 is Trek's entry-level triathlon/time trial bike. The frame has the Kammtail Virtual Foil aero design employed by the more expensive bikes like the 9.9 that Mat reviewed, only here it's aluminium. The wheelset and gears, however, look like they've been borrowed from a sportive bike, and the tri bars are too high relative to the saddle.

This bike is aimed at triathletes on a budget. Fair warning: I am a time triallist. The bike requirements are the same, apart from the fact that triathletes want to be able to run when they get off, whereas time triallists want to be so spent they can barely walk. 'Budget' I get: my race bike has roughly the same replacement value as this, and I used to race on a modified Genesis Flyer.

For the Speed Concept 2.5, budget means an aluminium frame, albeit hydroformed into just the shape Trek want: that Kammtail Virtual Foil. It's essentially a long aero section with the back end chopped off. The intention is to maximise the frontal aero benefits while minimising any problems from side winds.

My vernier callipers give the following tube measurements at the thickest points: down tube 81.5 x 30mm; seat tube 80 x 32.5mm; seatpost 69 x 20mm. Trek say it's the most aerodynamic shape ever designed for a bicycle, and it certainly looks the business. Fellow racers appraised it keenly.

However, the aerodynamics of the frame itself isn't a huge deal in terms of the seconds it will save. The most important thing is the aerodynamics of you, the rider: your position, your skin-tight gear, and your pointy hat. After that you want deep section (or rear disc) wheels with the fastest-rolling tyres you can finish your race on. A faster frame is incrementally helpful but it's not a substitute for these other factors – as I found out when I raced it.

Frame, fork & fit

Two things are striking about the frame, apart from the tube profiles. Thing one is the attention that's been paid to aero details. The cables run internally. The rear brake is mounted out of the way underneath the chainstays. The junction between the head tube and the carbon fork (aluminium steerer) is neatly filled in.

Thing two is the steep seat tube angle, a feature common on aero bikes these days but which was largely introduced by triathletes. I measured it at 78.5 degrees. The effective seat tube angle will depend where exactly you clamp the saddle rails and whether you set the clamp facing forward or backward on top of the post; layback is plus/minus 10mm. Whatever you do, the angle will be somewhere between very steep and very, very steep.

The benefit of this for time trialling (and presumably triathlon) is that you can get forward over the bottom bracket. This opens up your hip angle: for a given torso angle, you end up bending less acutely at the waist than you would if you were sitting further back. If feels less squashed and it's good for putting the power down when you're on the tri bars.

If you're sitting further forward, you want the armrests a bit further forward too. (Note that CTT regulations state that the back of your elbow can't be more than 3cm in front of a line drawn through the centre of the head tube, so there's a limit to how far forward you can go.) On the Speed Concept 2.5, the armrests aren't further forward.

Reach is unusually short on this bike. The effective top tube length is only 52cm, which is small for a Medium sized bike. It's that short not because Trek have scrimped on the front centre distance – they haven't; there's enough room between the front hub and the bottom bracket to avoid toe overlap, a nice bonus on a race bike – but because the steeper seat tube eats into the top tube length. The cables that bulk up behind the stem are close enough to catch your knees on if you get out of the saddle.

A longer stem would maintain the saddle-to-handlebar distance. This one is 8cm, and just sitting on the bike in a TT position, I felt cramped. I wanted a stem about 12cm long, maybe longer. That's not an expensive or difficult upgrade, admittedly. The alternative, even though I am only average sized, would be to go up a size to the Large. The knock-on effect of that would be to raise the handlebar by another 2.5cm, since the Large bike's head tube is that much taller. A higher bar is the last thing I'd want; even a glance showed that there wasn't much drop from the saddle to the armrests.

The tape measure confirmed this. With the stem at its lowest point on the steerer, the relative position of the armrests on the Trek was more than 6cm higher than those on my own bike. (That has a dropped stem, true, but I could get the same bar position on my bike with a flat stem; the dropped stem gives scope to go another 2-3cm lower than shown.) The reason for the Trek's high bars relative to the saddle is a combination of a few things, the smallest of which is crank length. (I race on 165mm cranks.)

The two big differences are the tri bar arrangement and the bottom bracket height. The Trek's armrests fit on top of the tri bar extensions, which themselves sit on top of the base bar. While you can turn the tri bar brackets upside down to run the extensions underneath the base bar, the armrests then won't fit properly because the base bar is in the way. If this were my bike, I would immediately ditch these Bontrager tri bars and fit some with lower armrests. Easton Aeroforce bars would do it – they're about £90 – and there are plenty of others.

The bottom bracket height is something you can't change. It's deliberately low. Trek have made it low 'for stability', they say. On corners, they may have a point; in a straight line, like what you do in time trials most of the time, I've not found that bottom bracket height makes a difference, even on the tri bars. The other effect of lowering the bottom bracket height is that it lowers the saddle height, and reduces the drop from saddle to handlebar, by the same amount. Result: you sit that much more upright.

There are a few unusual frame/fork features. The fork is 'SpeedTrap compatible', so you can fit a computer sensor without messing up the airflow around one of the fork legs. If you use a wheel magnet computer rather than GPS, this is a worthwhile extra. There are a couple of sets of bottle bosses, and what looks like a third set on top of the top tube, behind the stem. This is for a Speed Storage box – essentially an aerodynamic Tupperware box for snacks. I didn't have the opportunity to try this.

Components

The Speed Concept's sophisticated frame and fork no doubt absorb quite a bit of the entry-level budget, so there isn't money left for fancy wheels. You get straightforward aluminium clincher rims with 23mm road tyres; the only nods towards speed are the spokes (24 per wheel rather than 32, and they're bladed) and the cool-looking aero quick releases.

Deep section carbon wheels aren't cheap, so it's understandable that they're absent on this entry-level bike. But you definitely want faster tyres. I'd fit Continental Grand Prix Supersonics with latex innertubes.

The groupset is Sram Apex with bar-end levers. Apart from the levers, it's Sram Apex as you would fit it to a sportive bike: 50-34 compact chainset and an 11-28 cassette. On a time trial or triathlon bike, this is a bizarre setup. A 34-tooth chainring is neither use nor ornament, and if you find yourself using it in a race, you may as well sit up and pedal gently back to the finish. The 11-28 cassette means that you have relatively wide steps between gears, potentially spoiling your racing cadence. A compact double and a wide cassette make sense on a road bike, which you might ride recreationally or race somewhere hilly. On an aero race bike like this, even if it's meant for novices, sportive gearing makes no sense at all.

The cranks are slightly longer than most average-sized bike riders would normally use, being 172.5 rather than 170. I can't say I noticed any difference when pedalling, but it does mean that the saddle will be slightly lower. And you'll have 5mm less room between your knee and your chest at the top of the pedal stroke – a consideration if you can adopt a very low tuck.

You don't use brakes much when time trialling, but these worked fine. The aero levers are a nice touch.

The ride

The acid test on a TT bike is: how fast do you go on it? Given that I was sitting more upright and felt a bit cramped, I thought I'd be slower. I was. Racing 10-mile TTs on courses that I know well, with the same kit, the same heart rate, and similar weather conditions, I was 45-60 seconds slower. That's measured against my own times in events just days apart, and more importantly against competitors who were present each time I was racing.

Some of this is down to wheels and tyres: my own bike has 50mm carbon rims and Schwalbe Ultremo TT tubulars. Some of it may be because of the gearing. Much of it, I'm sure, is down to the riding position. I couldn't get aero enough. It was marginally better when I slid the saddle right back to try to gain some breathing room.

Whether you'll run into this fitting problem is hard to say. It depends how tall you are, how much of your height is in your legs compared to your torso, and how low you want to go when you're on the tri bars. If you're taller, and particularly if you've got relatively long legs, you'll automatically get more drop from the saddle to the bars than I did.

For what it's worth, I'm average height (178cm), averagely proportioned (maybe a little longer in the torso), and not particularly flexible, due to some fused vertebrae in my lower back. If this review and Mat's of the 9.9 don't seem to chime, it's worth bearing a couple of things in mind: firstly, that the 9.9 is a much more expensive and much nicer bike; and secondly, that Mat is 12cm taller than me.

Despite what the blurb promised, I didn't find the Speed Concept 2.5 especially stable when riding on the tri bars. I'm used to having more bodyweight bearing down on the armrests, so the steering actually felt quite light and wandery.

Summary

The Trek Speed Concept 2.5 has a nice, aero frame, but everything else, including – for me - the riding position, is a bit of a let-down. It's not a bad bike but I wouldn't choose to race on it unless I could immediately spend another £200 on it. I'd get a longer, steeply dropped stem, different tri bars, and some faster tyres and tubes. (New wheels and gears would have to wait.) The other option would be to use that extra £200 to get a different bike: £1600 buys a carbon Planet X Stealth with 82/101mm carbon wheels and better gearing.

For racers taller than me, and for those who don't want as much drop between saddle and handlebar, the Speed Concept 2.5 could represent a good investment. There are things you'll want to upgrade – not least the weird sportive-style gearing and the non-aero wheels – but this chassis is worth hanging some upgrades on. Yes, it's aluminium rather than carbon, and that means a weight penalty, but for racing against the clock, aerodynamics is a bigger concern. Just make sure that you'll be aerodynamic enough when you're sitting on it before you go ahead and buy it.

Verdict

An aero aluminium frame with a curious component selection and a riding position that's too sat up for flat-out TT speed