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Patent Pending: Yamaha XS400 “Roadster”
Posted: Mon Mar 30, 2026 8:57 pm
by KungFooBob
I saw a vid on Friendface and thought it was AI so had a google.
Turns out is real, from a couple of years ago.
Looks kinda cool, shame about the motor
https://www.bikebound.com/2024/03/26/xs400/
Odd setup for the brakes/suspension...
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Mon Mar 30, 2026 8:59 pm
by weeksy
Wtf is going on there?
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Mon Mar 30, 2026 9:00 pm
by KungFooBob
weeksy wrote: Mon Mar 30, 2026 8:59 pm
Wtf is going on there?
Most importantly, Roman wanted to test a new front suspension concept he’s been developing, a Progressive Upside Down Fork (PUSDF) assembly intended to minimize dive under braking — a system he’s in the process of patenting. There are three patent claims:
1. Progressiveness — for example, for a 120 mm suspension travel of the wheel, there is a 60 mm lift in the fork.
2. When springing, the axis of the front wheels is pushed forward and thus eliminates the shortening of the wheelbase.
3. Separation of spring and braking force — the motorcycle does not dive when braking.
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Mon Mar 30, 2026 9:03 pm
by Skub
It's a very tidy bike visually. The C90 fork/suspension arrangement sort of runs against the 'simple' ethos. Looks too clever for me.
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Tue Mar 31, 2026 7:09 am
by Bigjawa
KungFooBob wrote: Mon Mar 30, 2026 9:00 pm
weeksy wrote: Mon Mar 30, 2026 8:59 pm
Wtf is going on there?
Most importantly, Roman wanted to test a new front suspension concept he’s been developing, a Progressive Upside Down Fork (PUSDF) assembly intended to minimize dive under braking — a system he’s in the process of patenting. There are three patent claims:
1. Progressiveness — for example, for a 120 mm suspension travel of the wheel, there is a 60 mm lift in the fork.
2. When springing, the axis of the front wheels is pushed forward and thus eliminates the shortening of the wheelbase.
3. Separation of spring and braking force — the motorcycle does not dive when braking.
Dive? There's about 25mm of fork travel....
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Tue Mar 31, 2026 10:07 am
by Rockburner
The forks are certainly interesting....
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Tue Mar 31, 2026 10:25 am
by Taipan
Looks like he's solved a problem those forks didn't have! Quite like the simplicity of the rest of it though.
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Tue Mar 31, 2026 7:49 pm
by Le_Fromage_Grande
The XS400 engine is very underwhelming
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Tue Mar 31, 2026 7:50 pm
by KungFooBob
Le_Fromage_Grande wrote: Tue Mar 31, 2026 7:49 pm
The XS400 engine is very underwhelming
It also looks massive for a 400 twin.
Re: Patent Pending: Yamaha XS400 “Roadster”
Posted: Tue Mar 31, 2026 8:11 pm
by Ian
Le_Fromage_Grande wrote: Tue Mar 31, 2026 7:49 pm
The XS400 engine is very underwhelming
That's a bit of an understatement