How fast can a steel fixed wheel bike go?

This might be of interest to some of you. I’ve been working with Neil “Soupy” Campbell for a few years now on his quest to become the worlds fastest cyclist.

His aim is to break the long standing Absolute World Speed Record of 268.831km/h (167.044 mph) set by Fred Rompelberg in 1995. This is a motor paced record.

He’s already broken Guy Martin’s British record back in 2016 on an old tandem behind a VW Passat and next week aims to break the European record of 127mph.

The new bike is built by MOSS Bikes who also build bikes for the Redhook Crits.

You can follow his progress on Facebook (https://www.facebook.com/operationpacemaker/) and Instagram (https://www.instagram.com/operationpacemaker/).

For the number crunchers out there... the gearing on the bike, which is based on a fixed gear cross over drive, will be about 460” in old money.

That’s equivalent to around 245x14 on a standard road bike...

Will be even bigger for the World Record attempt.

Steel is real, thanks for sharing

It sure is. Moss build the bike from a mix of Reynolds tubing. Mostly 953 Stainless with bespoke 3D printed Stainless Steel lugs and yokes.

It’s a beast. :-)

It’s a beast. :-)

Yep!

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followed

Saw this thing at bespoked - absolutely bonkers. Good luck!

Wouldn't the sprung saddle reduce power transfer?

wild! good luck!

Nice to see that fid has got behind it as well .

Is it significant that that bike has basically no hallmarks of a conventional "fast" bike? Or at these speeds are the rules completely different?

Remove the pace vehicle and the bike will not achive the speeds.
The bike is not having to slice through the air the car is doing that job and needs a big engine and aero mods to kinda tow the bike along.
You still need the big gears to spin up to that speed.

On rollers i can spin up a 44x17 to 44mph, i can't do that on the road as i need way more power to punch/slice/slip through air density.

It's still effing fast and rather dangerous :)

Rompelberg in 1995...

While the pace car is punching a hole in the air it still takes a significant amount of effort to achieve those speeds. Just try pacing behind a fast wagon on an A road at 50mph. It's not like riding on the rollers. :-)

The reason for the shape of the bike being "unconventional" is that to keep the bike stable at that speed they've gone for a long wheelbase. It does not need to turn fast... just needs to be stable in a straight line. They've also gone for motorcycle technology (wheels and front end) as bicycle tech, especially the wheels and tyres, is just not designed for those speeds. So that also influences the design of the bike.

Not having to be "aero", much like a stayer or derny racer, also influences the position.

So is that strength the reason for the small wheels?

What's happening at the drivetrain? Is that a double chain?

No. As I said above... long wheelbase for stability. Small wheels are that are motorcycle wheels. They don't make bicycle wheels and tyres that can deal with the speed Neil is aiming to do.

Cross over drive so that we can get a gear ratios big enough.

64t on the front, that drives a 15t which drives a 58t on the opposite side of the bottom bracket. That then drives a 13t on the rear wheel.

Would be the same as having a 245t x 14t on a standard bike... about 460 inch gear in old money.

We can increase that gear by changing the combination, some this line there for instance:
68t x 14t x 64t x 13t would give an even bigger gear of about 580 inch which would be needed for World Record speed. That's something like 255t x 12t on a normal road bike.

I'd love to show this bike off in my Physics classes.

Air resistance,power,gear ratios. Theres about a month worth of teaching here!

Just for some context on chainring size.

That's a Royce custom 104t chainring.
So the double chain drive system because a 245t chainring would be impractical .

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Damn, that's a very cool solution. Must be fun for the knees getting it up to speed..

I think they had a donhou at a rollapoluzza event a few years back at the short lived look mum2.

Everyone tried to beast it and get up to speed in 20 seconds instead of slow and steady for a minute...

Article and video here Craig maclean had to tape up his calf for clearance ha

Madness. Three thumbs up

Record attemp tomorrow (tuesday) will soupy hit 127 mhr 🙏