Bathtub Bike: 1958 Triumph Twenty-One 3TA

Some period Triumph ads referred to the bathtub bodywork on this 1958 Triumph Twenty-One 3TA as “mudguarding” and it had to have been nice in an era without as many paved roads as there are today. The seller has this really interesting and desirable bike listed here on eBay in interesting and desirable Kirkland, Washington. The current bid price is just over $3,500 and there is no reserve.

I have an unhealthy obsession for these shrouded bikes. I just barely missed out on a “styled” Moto Guzzi Ziggilo 110 as seen here from June of 2016, and it was only $2,500 – AND IT WAS LOCAL. Not that I’m still bitter or anything, but I’ve never forgotten that little beauty. A Triumph Twenty-One, which is a 350 cc, would be a much more usable bike and would be fantastic to own. It has a 4-speed constant-mesh transmission and, I think, a really nice clean look overall. This bike also has unit construction, in which the engine, gearbox, and primary case are all built into one common casing.

The Triumph Twenty-One hit the streets in 1957 and it’s not remotely the same as the slightly-modified 1950 Triumph Thunderbird 6T that Marlon Brando rode in the classic 1953 movie The Wild Ones. I don’t know if Brando would have appeared as tough as he did while riding a skirted motorcycle. Although, Triumph did offer one on the Thunderbird beginning in 1960. Enough of that, back to this Twenty-One. The company made the Twenty-One until 1966 and the styled/bathtub/mudguard – whatever you want to call it – bodywork was meant to keep both ride and bike clean, or cleaner than an open-wheel bike would.

Triumph made the 350 cc model known as the 3TA as this one is and they also made a 5TA, a 500 cc version, the Speed Twin. One of you will know (Geo?) where the name Twenty-One came from. I’ve found differing viewpoints about that, from either its 350 cc engine equating to 21 cubic inches or it was the 21st anniversary of Triumph Engineering. Or, maybe both? You can see that this bike needs a little help and some polishing. I think it’s cool as it looks now and I’d concentrate on making it drop-dead reliable (isn’t that an oxymoron?) and riding it as it looks now. But, there’s something to be said for a gorgeous, restored, styled bike, too. There should be a tank rack which I think may be missing, the seller mentions that there are a few pieces missing.

As I mentioned more than once, the engine is a 349 cc twin-cylinder and it would have had about 20 horsepower. The sad part is that the seller says it’s seized. Frankly, I’m surprised at the bid price for a bike in this condition with a seized engine, but it is 2021 after all, a year when some vehicles are literally off the charts, ones that we never thought would be so valuable, so anything is possible these days. Hagerty is at $4,200 for a #4 fair condition bike and with a seized engine this isn’t a #4 bike. Have any of you owned a styled/bathtub bike?


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  1. Howard A Member

    I bet if this was Asian, it would be in Scotty’s “lineup”. I think this has a normal looking frame under that “tub”, and many bikes of that time did use a pressed steel frame, like my Honda 50 that looked like that tub. Apparently trying to cash in on the huge Italian scooter market at the time. Not sure how much protection that tub would offer in the rain, I found, no matter what you do, you only buy time from getting soaked. As far as we were concerned,( in Beer City) there were only 2 makes of motorcycles, H-D and anything British. Europe and Asia had some incredible bikes, but we never saw them. If I had deep pockets, which I clearly don’t, I’d love to have project like this. It is so cool looking, even though riding it will quickly remind you of what riding a “Limey” is all about.

    Like 5
  2. Bill

    Much of the time the bathtub was discarded. This bike being complete may attract bids from those who want authenticity.

    Like 3
    • Frank

      Its all there. I had a 1959 Tiger, the Prince of Darkness model.
      Nice resto project.

      Like 3
  3. walt mcclurg

    I’d buy it just 4 ‘garage art’

    Like 2
    • man ' war

      I used to have a pedal motor bike. It looked French and seemed to be 60s or 70s. The engine was missing. And “garage art” was exactly how I had it – hanging on the rim from the ceiling hook. It was a little on the heavy side. I don’t recall what I paid for it at a garage sale, but I sold it for $20 bucks at the flea market.

      Like 1
  4. Robert Morris

    In the 1962-63 period I had a college roommate who owned one. He would let me use it and I loved it as it was a good handling bike but not real fast (20 hp.) so I felt safe. It was the same blue as pictured. I hope it gets restored!

    Like 4
  5. Al

    To me it looks more like a chamber-pot than a bath-tub.

    Like 4
  6. Terrry

    I don’t think this bike would give you any more wind and rain protection than a regular motorcycle, but it sure is unique and I like it. I’d jump in on the auction action if the motor wasn’t seized.

    Like 2
  7. Johnny

    I like it. I,d like to have this for something to restore during the winter months. Pull the plugs and spray kano oil in it and lets it soak.Then about a week.Start moving the rear wheel back and forwards a little at a time. Take you time and it will work loose. Then work on other parts of it. Yes, I like it and it would give me something to do. Then when your done. You,ve learnt with paitence–you can do it.

    Like 3
    • Howard A Member

      A trick I learned ( on my own) is on an air cooled motor that stuck, the usual mix of fuel oil and PB Blaster, let it sit a spell, then warm the cylinder with a torch. The heat expands the cylinder, but not the piston(s), and I bet it breaks free.

      Like 3
  8. walt mcclurg

    A limey Moped maybe back in the day? just saying

  9. geomechs geomechs Member

    A person always learns new things, even if he’s closer to 70 than 65. I always thought that Triumph introduced Unit-Construction in ’63. Obviously it was earlier for the smaller units and only adapted to the big twins later. Bert Hopwood (chief designer for Triumph back then) was always a champion of Unit-Construction but he constantly locked horns with Edward Turner who had a nasty habit of vetoing every proposal Hopwood came up with. Turner was the designer of the SPEED TWIN back in 1937. The Speed Twin’s success went to Turner’s head and he formed the attitude that no one could improve on such “perfection” (you should never promote a brilliant designer to management).

    The “21” designation, to the best of my knowledge, was merely the CID of the engine. Triumph was building 350s for quite a few years before this model was introduced so the “21” designation. I might add that Turner might have attempted to exert some ‘influence’ on the 21, being 21 years since he designed (not introduced) the Speed Twin but I think that 21 stood for the size and nothing more.

    Now for this bike. Just load it up and take it to my place. I need another project to fill my days (insert laughing here). I really like this bike and it would be a great deal of fun to ride it through the masses of Tokyo Trash Cans. What? Honda didn’t invent the motorcycle? Oh, it was Yamaha. No? Kawasaki! Suzuki? Now, you’re pulling my leg. I’m going to have to write that down in my copy of The World’s Motorcycles 1896-1963. Sorry guys. My morning jump-start hasn’t quite hit me yet so I’m a little cynical. Besides, my wife left me–to go see the GRANDKIDS (I go meet her in a week’s time) and I’m in this house all alone, getting into all kinds of mischief…

    Like 4
  10. Scotty Gilbertson Staff

    Auction update: this one sold for $3,655.99.

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