You’re standing at Bray Hill. Your feet are literally vibrating because a 600cc engine is screaming toward you at 140mph. But it’s not a bike. Not exactly. It’s this low-slung, asymmetrical three-wheeled machine that looks like it belongs in a sci-fi flick from the seventies. And then you see the passenger. He’s hanging off the back, inches from the asphalt, head tucked behind a wheel, body acting as a human counterweight. This is the Isle of Man sidecar experience. It’s chaotic. It’s beautiful. Honestly, it’s probably the most terrifying thing you can do with a helmet on.
Most people think sidecars are just a side-show to the "real" TT races. They’re wrong.
While the solo bikes get the headlines, the sidecars are arguably more technical. It's a dance. If the driver and the passenger—usually called the "ballast" or "brawny nutcase"—aren't perfectly synced, they’re going into the wall. There is no middle ground at the Snaefell Mountain Course. You either get it right, or the 37.73 miles of hedges, stone walls, and manhole covers will let you know exactly where you messed up.
The weird physics of the Isle of Man sidecar
A solo bike leans. It’s natural. Physics wants the bike to lean into a corner. A sidecar? It hates corners. Because the machine is asymmetrical, it wants to tip over every time you turn right (in a left-hand sidecar setup). This is where the passenger comes in.
They aren't just sitting there enjoying the view.
The passenger is constantly moving. When the outfit—that's what we call the rigs—turns right, the passenger has to throw their entire body weight over the sidecar wheel to keep it on the ground. When they turn left, they’re hanging out the other side to keep the rear wheel planted. Watch a guy like Dan Sayle or the Birchall brothers. It looks like gymnastics at 150mph. If the passenger is late by half a second? The outfit flips.
Dave Molyneux, a legend with 17 TT wins, once basically said that the sidecar is a machine that shouldn't work, but through sheer willpower and a bit of engineering madness, it does. He’s built his own frames for years. In the sidecar world, the top guys are often the ones building the damn things in their sheds. It’s incredibly grassroots compared to the factory-backed solo teams.
Why the 600cc limit exists
You might wonder why they don't use 1000cc engines like the Senior TT bikes. They used to have more variety, but currently, the rules are pretty strict: 600cc four-cylinder engines (mostly from the Honda CBR600RR or Yamaha R6) or 900cc parallel twins.
Why? Because the chassis can only handle so much.
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The Isle of Man sidecar outfits are incredibly light. If you put a 200-horsepower liter-bike engine in there, the power-to-weight ratio would make the thing virtually undrivable on the bumpy, narrow roads of the Island. The 600s are the "sweet spot." They allow for incredible corner speed without the raw torque tearing the tires to shreds or sending the outfit into a permanent slide. Ben and Tom Birchall have dominated this class recently because they treat it like a science. They don't just "drive"; they manage the momentum. They broke the 120mph lap record because they found a way to carry speed through places like Ballagarey where most people would be praying to whatever god they believe in.
The "Passenger" is a bit of a misnomer
Let’s talk about the passenger.
Calling them a passenger is like calling a co-pilot in a fighter jet a "traveler." It’s insulting. The passenger is the active suspension. They are the traction control. At the TT, the passenger’s job is to read the road ahead of the driver. They know every bump. If there’s a jump at Ballaugh Bridge, the passenger has to time their landing so they don't break their wrists or bottom out the suspension.
It’s a brutal job. Your knees take a pounding. Your neck is constantly strained against G-forces. And the heat? You’re tucked right next to an engine and an exhaust pipe that’s glowing cherry red.
I’ve talked to guys who have finished a three-lap race and literally couldn’t uncurl their fingers from the grab handles. The grip strength required is insane. But they do it for the buzz. There is no other feeling like being six inches off the ground at Glen Helen, seeing the sparks fly off the skid plate.
The Birchall Era and the evolution of the lap record
For a long time, the 110mph lap was the holy grail. Then it was 115mph. Now, we’re looking at the 120mph barrier being shattered.
The Birchall brothers changed the game. Tom (the passenger) and Ben (the driver) brought a level of professional athleticism to the Isle of Man sidecar class that wasn't always there. In the old days, it was about grit and mechanical sympathy. Now, it’s about data. They look at entry speeds and lean angles like Formula 1 engineers.
When they set the first ever 120mph+ lap in 2023, the Island went mental. To average 120mph over 37 miles on a three-wheeled vehicle is, frankly, stupid. It shouldn't be possible. The roads are too crowned. The bumps are too violent. But they did it by being smoother than anyone else.
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- 2013: Tim Reeves and Dan Sayle win, proving that the old guard still had it.
- 2015: The Birchalls start their reign.
- 2023: The 120mph lap record falls.
It’s worth noting that the sidecar community is tight-knit. If a team crashes in practice, rival teams will be in their paddock tent until 3:00 AM helping them weld the frame back together. You don't see that in MotoGP. There’s a shared understanding that what they’re doing is uniquely dangerous, and that creates a bond that transcends the trophy.
What it’s actually like to watch (The Fan Experience)
If you go to the Island, don't just sit in the Grandstand. That’s for tourists.
Go to the bottom of Barregarrow. You’ll see the sidecar outfits bottom out so hard that the entire chassis throws up a massive curtain of sparks. The noise is different, too. It’s a high-pitched, angry wail that echoes off the stone walls. Because there are two people on the machine, you can see the communication. You see the passenger look back, check the gap, and then dive into the next "chair" position.
Honestly, it’s more visceral than the solo bikes.
You can see the effort. You see the muscles tensing. You see the machine dancing on the edge of adhesion. At places like Cronk-ny-Mona, where the road drops away, the sidecars look like they’re hovering. It’s hypnotic.
The risks nobody likes to talk about
We have to be real here. The Isle of Man sidecar races have a dark side. It is dangerous. When things go wrong in a sidecar, they go wrong in a very "big" way. Because the machines don't lean, they don't "lowside" like a bike. They flip. Or they hook a wheel in a hedge and stop instantly.
We lost the Crowes (Ryan and Callum) from the entry lists for a while after big accidents. We’ve lost legends. The sidecar community deals with grief differently. They acknowledge it, they respect the mountain, and then they get back in the chair. It’s a specific type of stoicism that you only find in the Manx community.
Some critics say it’s too dangerous. They say the machines have outgrown the course. But if you ask the drivers, they’ll tell you that the danger is why it matters. It’s the ultimate test of man and machine working in total harmony. If you sanitized it, it wouldn't be the TT.
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Technical quirks you didn't know
Most outfits use a "slinker" or "long" chassis now. Back in the day, they were much shorter, which made them twitchy. The modern LCR (Louis Christen Racing) frames are masterpieces of engineering.
- Steering: It’s not like a car. It’s more like a direct-linkage system that requires massive upper body strength.
- Braking: Most have linked brakes, but the driver has to manage the bias so the sidecar wheel doesn't lock up and pull the whole rig into a spin.
- Tires: They use flat-profile slick tires, which look like miniature F1 tires. They have a very narrow operating window. If they’re too cold, you have zero grip. If they’re too hot, they turn to grease.
How to get into sidecar racing (If you're crazy enough)
You don't just show up at the TT. You have to earn your stripes. Most guys start in the British Sidecar Championship (FSRA). You learn how to handle the "outfit" on short circuits like Brands Hatch or Donington Park.
You need a partner you trust with your life. Literally. Most successful sidecar teams are families—brothers, fathers and sons, or best friends who have known each other for decades. You need to be able to anticipate what the other person is going to do before they do it.
- Step 1: Find a local club.
- Step 2: Get a passenger license (it’s easier than a driver license to start).
- Step 3: Realize that you’re going to spend all your money on tires and petrol.
- Step 4: Keep your head down and your weight low.
What’s next for the three-wheelers?
There’s talk of electric sidecars. It’s been tried in the past with the MotoE-style tech, but the weight of the batteries is a huge issue for a machine that relies so heavily on weight distribution. For now, the internal combustion engine is king.
The battle for the next few years will be between the old-school engineering of guys like Dave Molyneux and the high-tech precision of the younger generation like the Birchalls or the Founds. We’re also seeing a massive influx of newcomers from the Isle of Man itself, which is great for the longevity of the sport.
The Isle of Man sidecar isn't just a race; it’s an anachronism. It’s a throwback to a time when racing was about two people, a toolbox, and a desire to see how fast they could go on a public road. It defies logic. It defies safety. And that’s exactly why we can’t stop watching.
Actionable Insights for Fans and Aspiring Racers
If you're planning to head to the Isle of Man to witness this madness, or if you're genuinely considering getting into the "chair," here's what you actually need to do:
- For the Spectator: Download the TT+ Live Pass. It’s the only way to see the onboard footage from the sidecars, which is arguably more exciting than the solo bikes because you can see the passenger's work in real-time. Position yourself at the Bottom of Barregarrow or The Bottom of Bray Hill for the most dramatic sidecar action.
- For the Aspiring Racer: Don't buy an outfit immediately. Go to a "test day" hosted by the FSRA (Formula Sidecar Racing Association) in the UK. They often have "passenger schools" where you can try it out in a controlled environment before you commit thousands of pounds to a rig.
- For the Tech Nerd: Study the "Leading Link" front suspension. It’s the secret to why these machines don't collapse under heavy braking. Understanding the mechanical trail on a sidecar front end is a masterclass in unconventional geometry.
The sport is evolving, but the core remains the same: two people, three wheels, and a 37-mile mountain that never forgets a mistake. Respect the mountain, and it might just let you break a record.