Built to budget, spec’d for speed: Where to start building your own tri bike
Go to a specialist to build your dream tri bike to order and things can soon get a bit… pricey. But is it possible to do it yourself for less? Bruce Wilson decided to have a go ahead of his next tri…
The internet is a dangerous place; one minute you’re asking it for advice on pruning hydrangeas, the next you’ve fallen down the rabbit hole of looking for bargain tri bikes.
I must admit, casually scanning Facebook Marketplace has become a bit of a habit in recent times, so when I stumbled across a frame for a Giant Trinity, I wasn’t even looking for one. But there it was, luring me in with its provocative £500 price tag.
Nope, it didn’t have wheels, extensions, a group set or even crank arms for that matter. But it was blue, and it was cheap, and it was located just 15 miles down the road – I had to have it. A message of intent was sent, and a time and location was fired back my way in return. The deal was on.
Can you build your own triathlon bike?
It’s at this point that I should profess I’d never owned a proper tri bike before, competing for over a decade on road bikes with clamp-on tri bars to achieve aerodynamics marginally greater than my garden shed. In the last few years, I’ve started to take triathlons that bit more seriously and reasoned that the ‘cheat code’ I was lacking was the coveted tri bike. Surely, it’d make a difference and give me an edge in the discipline I like most?
Such thoughts ladened my mind as I jettisoned the kids’ car seats, to make room for my new acquisition, before heading off into the distance, destined for a nearby McDonalds. Under the watchful eyes of families devouring enough calories to power an Ironman, I came face to face with the seller and the Trinity.
‘Do you want to take a look around it’, he asked? Well, I did, but there wasn’t really that much to look at, barring the scuff on the seat post, and the other up by the headstock. It was as skeletal as any other bare bone frame you’ll see, so I saved him and I the time of delving deeper and handed over the money that’d been destined for a day out at Peppa Pig World.
Akin to that moment when you leave the hospital for the first time with a newborn in the car and keep checking rearwards on your precious cargo, I was both proud and excited by this latest addition to the family on the return leg home.
I’ve always been a glass-half-full kind of guy, and I love a challenge. I’d also say that I love building bikes, but that’d be a lie as I’d never done such a thing before. I really didn’t have much of a clue about what’d be needed to transform the Trinity frame from mere carbon fibre wall art into a time slashing sensation… but I knew a friend that did.
If you’re into triathlons, I’d be surprised if like me, you don’t know of at least one person that can give you a pointer towards the length of crank arms needed to suit a build. I was also able to grasp the stock fitment cassette and front chain ring sizes, which I was intending to mirror.
What I didn’t want to match was the build cost of a new bike. The cheapest version of the 2025-spec Trinity (SL 2) hits home at a tear-inducing £6,499, while the £10,499 SL 0 would possibly provoke a divorce.
Both look fancy, both look fast, but both also look quite familiar to the design of the frame I’d just picked up for 500-quid. By comparison, Giant will sell you their bare Trinity frame for £3,750. All of this being the case, I reckoned I was off to a pretty good start.
As you’re probably picking up, money was a major factor with this purchase, and the intention was to build a bike of a solid spec for less money than one would cost in a classified advert.
The Trinity is a massively popular tri bike that’s been around for a long time, so I saw an abundance of used options online, ranging from as little as £850 to £5,000. The difference? Age. Spec. Colour.
Every seller argued the virtues of their model, justifying why it would cost you more than the one in the advert right next to it. Some differences were blatant, while others required the vigilance of ‘Where’s Wally’ to work out how they’d got the pricing so spectacularly high.
The dearer ones were kitted with fancy wheels, 12-speed ratios and gram-saving carbon bolt-ons. Generally, the older the bike, the cheaper it was.
It seemed that two-grand was a good ballpark for a reasonable example… but being tight, I was on a mission to get this build’s cost down nearer to £1,000. Deluded? Quite possibly, but through incessant internet-scouring, a few shiny trinkets started to pop up at the right price.
Time to shop
The first purchase, and perhaps the biggest bargain of all, was a complete Shimano Di2 groupset for £300 (11-speed). It even came with shifters, a battery and the charger. I bagged it, before finding a barely used Ultegra crankset for just £80. My mate Rob had some decent carbon wheels for £200, and I found a tri saddle and Ultegra pedals loitering in my own garage.
As much as I love a bargain, I’ve always been a firm believer in spending, when necessary, on consumables that demand the utmost integrity, so items like the Ultegra chain, Swisstop brake pads and the rear cassette were all-new.
Other items that hit the wallet that little bit harder were a box-fresh Token Ninja bottom bracket and Shimano bar end shifters. Add all this lot together and the total had arisen to well over a thousand pounds. But after lying down for a little, I figured the build was still something of a bargain. Now all it needed was building…
Building the bike
I’m genuinely not shy of getting my hands dirty, but Rob’s enthusiasm for the build, and his knowledge for bikes, meant that I dropped everything off with him, getting a text the next day to say he’d completed it. A few beers were exchanged, and off I went for a joyride on my new Trinity. First impressions? A torture rack with the predictability of a scolded cat. What the hell had I just done?
My go-to bike is a 2022 Giant Propel Advanced Disc 1; it is quick, comfortable and stable. The Trinity, on the other hand, didn’t feel any of those things as I put it through its paces on that inaugural ride. Of course, Rome wasn’t built in a day, and while the same can’t be said for my new toy, the finishing touches would undoubtedly make a huge difference to it.
As anyone that’s ever ridden with tri bars will know, being comfy is sacrosanct. Altering the ergonomics was going to be a major priority of mine, but so too was making the build more versatile.
With a few rides under my belt, I realised that the Trinity would be a lot more pleasurable if I could change gear on the drops… not just on the extensions. Marketplace came to the rescue once again, in the form of a bloke selling a pair of Dura Ace brake/shifters.
He wanted £150 for them, which was a bargain when compared to the new list price for such luxuries. But as is often the case when you head off down an alternative route, it also meant I’d need to buy a 5-port junction box… so an extra £69.99 swiftly left my bank account.
And before I had chance to stop and breathe, I hit ‘buy now’ on some Michelin Cup 2 TLR hoops, meaning I could run the Giant tubeless – which is always my preference.
Riding long
Thankfully, there were no other glaring parts needed before being able to use the bike in anger at an Olympic distance club event. The ride was just under 30-miles and the route was relatively flat, so I figured there’d be no better time to unleash the virtues of the tri bike, in which it performed well – powering me to a third place finish.
Several tweaks to the seat and the stacks ahead of time had made the riding position that bit more tolerable, so I was borderline comfortable on the bike. It felt fast, precise and less sketchy… but I’d stop short of saying it was perfect.
In reality, it can be made better still, and that’s the aim over the coming weeks ahead of using it in a middle-distance tri. Comfort is still its Achillies’ heel, and the main reason I elected not to use it in a recent full ironman-distance event. I’ve got my eye on a few components that will enhance the cockpit area and improve the ergonomics.
The problem is, as you’ve probably grasped, all these ‘tweaks’ come at a price and prompt the question, has it been worth it?
I don’t honestly know the answer to that right now. What I do know is I’ve got a relatively high-spec rig that didn’t come with a sketchy backstory, half-stripped bolts or more owners than a rental hot tub. That’s a win. Plus, I’ve genuinely enjoyed the build process.
All told, I’m £1,850 down, but I’m confident I’d claw that back if I sold it. Not that I’m tempted to. For now, the Trinity stays. If nothing else, it’s become my very own two-wheeled black hole for disposable income, and I can’t wait to see how much more cash and dignity it can suck in.
Counting the cost…
If there’s ever there was a list to keep hidden from your better half, this is it…
Giant Trinity 2018 Advanced Pro frame (used) …………………………………. £500.00
Shimano Di2 11-speed (used) ………………………………………………………… £300.00
Shimano extension shifters (new) …………………………………………………… £49.99
Shimano 5-port junction box (new) …………………………………………………. £69.99
Shimano Ultegra chain (new) ………………………………………………………… £30.00
Shimano Dura Ace shifters/brakes (used) …………………………………….. £150.00
Shimano R8000 chainset (used) …………………………………………………….. £80.00
Lezyne tubeless valves (new) ………………………………………………………… £20.00
Michelin Power Cup TLR tyres (new) ……………………………………………. £105.00
Swissstop brakes – front and rear (new) ……………………………………….. £40.00
Giant underseat battery retainer (new) ……………………………………………. £9.99
Token Ninja 3-in-one bottom bracket …………………………………………….. £70.00
Extensions (used) …………………………………………………………………………… £40.00
Giant armrests (new) ………………………………………………………………………. £39.99
Giant armrest spacers (new) …………………………………………………………… £53.99
Giant extension clamp set (new) ……………………………………………………… £29.99
Selcof Delta 56mm carbon wheels (used) ……………………………………… £200.00
Shimano cleats (used) ……………………………………………………………………. £30.00
Selle TRK saddle (used) ………………………………………………………………….. £30.00
Total: £1848.94
Is a tri bike right for you?
This was a question I asked myself. Having spent decades clocking tens-of-thousands of miles on road bikes, the idea of a tri-bike seemed a little alien to me. Yet, despite the concerns, the appeal of trying one still prevailed.
Over the past four months of owning this Trinity, it’s grown on me more so than I could have ever imagined. There’s no doubt about it; the Trinity is quicker than the Propel. I’ve also noted a lower heart rate despite achieving greater speeds. It’s true that the Propel climbs better and offers a more comfortable ride, but time in the saddle appears to be the answer.
The more familiar I’ve become with the Trinity, the more accepting I am of its more aggressive ergonomics and occasionally nervous front end. It’s like anything in life, it’s not without compromise and I’ve learned that the red lines for using it are exceptionally hilly routes, very windy conditions (upwards of 15mph) and on super rough surfaces.
In any of those conditions, it can be more of a handful than helpful, but it’s otherwise becoming a go-to option over my Propel.
Personally speaking, I’d say switching to a tri bike has unlocked another level in triathlon that I didn’t know existed.
220 Triathlon Team
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