Trinity MTB Debuts With a Steel, High Pivot, Gearbox Compatible Freeride Bike
Within the ManuFutures facility of Deakin University (Victoria, Australia), surrounded by numerous carbon fibre innovators sits Engineered to Slide, a motorsports fabricator. Between the endless row of metal cutting tools and one fast track car sat a half-finished frame awaiting the welding torch.
That was two days before the Handmade Bicycle Show Australia had opened its doors. By the time the show rolled around Trinity MTB was official and they had their first prototype rolling on two wheels.
That was two days before the Handmade Bicycle Show Australia had opened its doors. By the time the show rolled around Trinity MTB was official and they had their first prototype rolling on two wheels.
Trinity Details
Frame material: 4130 Chromoly front triangle, billet aluminium rear triangle
Intended Use: "hucking triples to flat"
Rear Wheel Travel:170mm (200mm Boxxer fork)
Wheelsize: 29" front, 27.5" rear
Weight: 15.2kg (single speed)
Price: N/A
More info: @trinity_mtb
Frame material: 4130 Chromoly front triangle, billet aluminium rear triangle
Intended Use: "hucking triples to flat"
Rear Wheel Travel:170mm (200mm Boxxer fork)
Wheelsize: 29" front, 27.5" rear
Weight: 15.2kg (single speed)
Price: N/A
More info: @trinity_mtb
Three makers who ride
Mick (left) and Nigel (right)
Trinity MTB is a new creation of three friends who all have riding in common and each brings a unique skillset to the table.
Based near to Geelong, Mick Williams is Trinity MTB’s engineer and also runs Williams Racing Products, a young bike component manufacturer who specialises in custom stems and linkage yokes. Nigel is the fabricator and runs Engineered to Slide. Judging by how he left the welding of his only prototype to the day before the show, he’s clearly comfortable with a torch in hand.
Nigel's experience as a fabricator is evident on this frame
Finally, there’s the designer, Chase Warner. Chase is based in California and so wasn’t present at the Handmade show.
Prototype Number One - idea basics
The goal of this first prototype was to create a test mule that could be chopped and changed to experiment and refine the suspension kinematics.
“We’re using a binematic patented by I-Track suspension. It’s a high pivot, but the high pivot moves independently of the axle path,” said Mick of the design. “In short we’re able to get really high anti-squat numbers while still having a high pivot and an axle path that moves backwards. It’s obviously something we want to test a lot, but could also be a bit of a game-changer.”
Trinity MTB has built this prototype with an interchangeable bottom bracket area, something that would allow them to easily produce mounts for the originally intended Effigear gearbox (which wasn’t sent in time by the company), a Pinion gearbox, or just a regular bottom bracket as pictured. For now, the bike is set up as a single speed, something that didn’t faze Nigel and Mick who come from BMX backgrounds.
The complex lattice can house an Effigear, a Pinion or a regular BB as shown.
“There hasn’t been a bike on the market that you could run a gearbox or a standard bottom bracket to do some quantity of testing to do some back-to-back testing to see what works. Work out lap times, efficiency in pedalling and that type of stuff.”
4130 Cromoly and surprisingly light
As shown and currently set, the bike is said to have 170 mm of rear-wheel travel, while the Boxxer on the front is set to 200 mm. In this configuration, the head angle sits at exactly 64-degrees.
The front triangle is made of .9mm thick 4130 Chromoly tubing, with the result being a bike that’s said to weigh just 15.2kg as shown. Of course, that weight is with just a single gear.
“I’m a huge fan of steel bikes, but we understand that aluminium is probably a better material to make them out of,” said Nigel. “I really wanted to start with a steel frame because we could do a lot of changes and modifications to begin with and it gives us some freedom in setting up and testing the kinematics of the bike.”
“From there we’d like to move to aluminium, but we’re also interested in doing a limited run of steel bikes.”
The rear end is currently aluminium billet but there's talk of a full aluminium build in the future.
They may have plans to chop and change the front end, but the rear end was machined from billet aluminium and so changes there are likely to be more costly.
As for when they’ll be ready for sale or at what price? Well, there’s no comment there. “We want to get into the forest on this thing and huck some triples to flat,” said Mick while Nigel nodded.
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158 Comments
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For a huck machine you just need the chain to stay on not a gear box you will rarely shift.
A DH race bike with a gearbox? Now you are talking.
For me I’ll wait for the all-weather, all-mtn, enduro-lite, 29/29’r with 130-150 rear wheel travel model.
When I was a hucker, I had it in my mind that I’m always going further, faster and higher. Pushing limits and fate.‘I’m going to crash often and bad. It’s just the price of admission. So why would I want a bike made of glass that lasts exactly one crash?
Why is aluminum outselling carbon in consumer DH bikes? Because we know we are going to crash and are not made of money with factory support trucks at the bottom of the hill with spare frames.
All of them.
...
...
Ok, all of em then.
That's not different to any other high pivot: a rearward axle path and potential for lots of anti-squat. The difference would be if they can dial the anti-squat without massive pedal kickback. Which is usually done with an offset idler, which this design also has...
Unless the pivot is really high though, you still need some amount of chain growth to generate a bit more AS and get it into that 'pedals well' range. This is where i-Track becomes very useful; it provides the designer with many options for positioning the idler in a suitable location so that it moves in a way that generates the chain growth you need.
Side note I did my engineering degree at deakin uni in Geelong.
Then I realized it was real and wondered if I was out of the loop.
I mean, the only reason we all deal with high anti-squat numbers on single crown bikes is because we have to pedal the damn things up hills.
They said they were missing the gearbox and therefore went with a single speed setup for initial testing.
I wasn´t talking about their fabrication skills, but the way the prototype was assembled. They also stated this proto was intended to be hacked apart and rewelded as necessary. Furthermore, it aparently has been assembled rather hastily if i got that right from the text. Not sure if component choices are due to lack of parts availability, but i wouldn´t put it outside the realm of possibility either. All this in summary suggests to me that this is indeed nowhere near what they´re trying to achieve with this project, but rather a first proto to evaluate nthe validity of the concept. So compared to what their next evolution will most likely look like (gearbox, aluminium, carefully selected components etc) i consider this a rather "ghetto" prototype. No harm meant in calling it that though.
The I-Track patent claims that by having an idler pulley fixed on the swingarm, lots of antisquat can be generated with very little chaingrowth (think, pedaling pulls the chain downwards on the idler, tugging the swingarm down, counteracting squat) and therefore very low pedal kickback.
I personally think pedal bob is an exaggerated problem. Frame flex, weight, drivetrain and tire selection all have greater effects on pedaling efficiency.
Congratulations to the team at Trinity for getting this prototype together against a tight schedule, with a couple of curve-balls thrown in along the way.
The i-Track suspension system is all about providing the designer with options for achieving their design goals. In this case, the high-pivot inverted Horst Link layout provides a rearward axle path without the increase in Anti-Rise (aka 'brake jack') that you would get with a high-single-pivot configuration. Having the idler 'floating' on the seatstay link means that the idler pulley can be positioned in a much more convenient location than it would have to be if it was 'fixed' on the front triangle. Additionally, by making small changes to the idler position (forwards or backwards on that seatstay member), Trinity has the power to test a huge range of Anti-Squat values, so they can arrive at a final product that meets all their expectations. Having the idler mounted in this way has provided flexibility for Trinity, and allowed them to package the suspension incredibly neatly.
Well done!
The man is a master at what he does.
I take it that could be a problem getting hold of a gearbox to fit the frames, too...................?
Maybe I just need to go try one.
I don’t know why, but it bothers me.
Do they even exist? I dare anyone to try and buy one.
And the boys were up for a good chat/discussion about it too.
If it fits every gearbox, and you couldnt get an effigear in time... Pinion boxes are available. Again. Proper planning....
"The goal of this first prototype was to create a test mule that could be chopped and changed to experiment and refine the suspension kinematics. "
Knowing how to weld is still important. Some of these have straight up holes through the work piece. I'm with Tim on this one.
Tig or GTAW with steel is incredibly basic. I could certainly do a better weld than that and I'm only a C level.
@z-man: Sure, on 1/8th wall tubing. Thinwall TIG is way trickier. I mean, you may be a good welder, and capable of doing better, but it's not "basic" by any stretch. Took me a lot of practice to make a decent bead on thinwall.
Yes there's people that can do a beautiful job of it, but you're not going to hire one for a prototype.
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