• I’ve been a long time lurker at the forum. Since I recently acquired two late nineties Principia Rex frames, I thought that these two builds could have some interest.

    First of the blue Principia Rex. I bought this bike equipped with Dura Ace 7700 (albeit the chain seems to be on the short side, shifting is fine though).

    The bike was equipped with a random finishing kit, so that was the first thing I wanted to change. In the heat of the moment I thought a full white finishing kit would look good (feel free to post in anti..), if I decide to keep the bike I might change this at a later point.
    I fixed the janky headset configuration, replaced the saddle for something cheap from BLB that i already had.

    Wheels where some older Shimano Ultegra fitted with random Bontrager tires. I replaced the wheels with a sturdy Mavic OpenPro/Shimano 150 combo. Replaced the tires with BLB Black Mamba, normally I would use Durano Plus due to the excessive amount of sharp stones on the roads here in Denmark. I really don’t fancy getting a flat and wanted to try tan-walls, so the BLB tires seemed like the way to go. Again, not quite sure on the looks.

    I have ridden about 200 km on the bike so far, and I’m really impressed with it. You can really feel that this was build with racing in mind. This bike Is going to be my GT-bike. But I’m so impressed by the frame that the other frame will be build as a fast race/crit bike.

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  • Next of the black Principia Rex. It came with the seat post collar, and the proprietary Principia Headset cups. The frame have never been build, but the paint is a bit tacky from being in a shed for +20 years.

    The cost of new bearings and the remaining parts for the Principia headset was pretty high compared to a new headset (i thought), why I decided to remove the cups – only to realised that the diameter of the headtube is 37mm (1 ¼”). So, I’m trying to source a EC37 headset or figure out some other solution. I really want to find a cheaper solution than a Chris King EC37 headset.

    The bike will be built with a black Thomson Elite finishing kit, 1 1/8 carbon fork (I might be able to source a NOS Principia fork (albeit not a period correct Musing fork).

    Not sure which wheels I will use. I might use a (with no stickers) a set of Campagnolo Scirocco with Shimano-body that I already have. Maybe I will go with some deep section carbon wheels if I stumble upon a good deal.

    I think that Ultegra R8000 would be a good fit. Might opt for something else if its a good deal.

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  • In addition to the two Principia’s I also own a Felt F4 (threaded BB – so no squeak) with Ultegra and some Chinese Carbon-clinchers (running tubeless with IRC x-guard tires). Weight is around 8kgs.
    As a rainy day/winter bike I have a Scott Speedster with 10 speed Tiagra with mudguards. I’ve fitted a PlanetX saddle, Campagnolo Scirocco wheels (these where really cheap due to the Shimano-body) and a 3T carbon bar.

    Nothing particular special about these, but both of them ride flawlessly.

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  • I’ve also got to fixed-gear projects that I need to fix (hopefully this summer).

    First a Ridley Oval. I don’t think it really needs any work, other than fitting a drop bar to it. Omnium cranks, random finishing kit. Mavic Rims with PlanetX hubs, seems to run ok. Might change the rear wheel for a Phil-Wood hub laced to a H+Son SL42 rim.

    I’ve also got a beautiful Orbea track frame (no pictures yet). It needs a new headset, but otherwise it is pretty much finished. I’ve got some Shimano HB-7600 hubs om Rigida DP18 rims, that I will use for this build.

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  • Nice Ridley. I have a feeling those rims are for disc brake use only though so careful not to ride the brake too much :)

  • Thanks for the information, didn’t know that will check the rimes regularly after (brake)use. The front brake is only used for emergencies and to keep the police happy. So I have only used brake once when dialling in the cable tension.

  • On paper, yes, but in reality they are the same as A319 but without the machined sidewall.
    I built a set for a friend, and he has used them daily on his single speed for 4 years.

    Also, great principias I always wanted a black rex.
    Is it painted or anodized?

  • Arh cool, seems I’m safe then. I really don’t want to use the brake as I want to keep the braking surface black. Anyways, I always use clip-less pedals and really don’t use the bike for driving in the city due to the toe overlap. I’ve got a citybike with SRAM Automatix that I normally use for my (short) commute.

    To my best knowledge it is anodized. Sadly a bit scuffed as the frame has been sitting in a shed at the former owners house (whom apparently was a bike mechanic at the Olympics in Sydney for a Danish triathlete). I’ve only paid the 300 quid for both Principia's, so still think it was a pretty good deal.

    Just took the blue rex for 2-hour spin (including 30 mins in a hailstorm). The bike weights 9,6 kg as pictured (without bottles). The wheelset including tires does contribute with 3kg alone. So with some proper parts the black rex might be under 8kgs.

    I’ve ordered a headtube reducer today, hopefully this allows me to use a normal EC34 headset and a 1 1/8” fork.

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  • I helped @t0-ster source a principia CK from a guy that had a few (some years back).
    They’re around and pretty useless for most other bikes.

  • Cool - it would certainly be the most optimal solution to source an EC37 headset. I’ve been searching the internet but they seem to be hard to get by. Due to the fact that the blue rex uses a 1” fork I just bought an EC30 (this was before removing the cups).

    I've reached out to Principia and they said that all Principia-retailers could source bearings for the proprietary Principia cups. So this might also be a solution.

    This might also be a possibility:

    Fingers crossed that the head tube reducer works properly, it would certainly make it easier to source replacement bearings etc. in the future.

  • Update on the black Principia REX. Head tube reducer received and installed – seems pretty neat, doesn’t really add a lot of stack height (this bike will be slammed).
    Next step is to source an original Principia 1 1/8 fork and an EC34 headset to go with it. This might take a week or two. I have also ordered a Thomson Elite stem – as I apparently have sold the one I thought I had.

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  • Found a shop in Denmark that could deliver a Principia fork overnight (NOS made by Mizuno). It’s not that light (only a couple of centimeters needs to be removed from the steerer), but it was cheap.

    I’m considering removing the clearcoat to match the matt look of the frame. Still waiting for the Thomson stem and some few small pieces before I can install the headset/fork.

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  • Headset installed, fork (except the cone – have to wait for another day, so that I do not disturb the neighbours).

    However I’ve made a major f-up.. When fitting the wheel I realised that the frame is for 650c wheels..

    The seller mentioned that he used to be a mechanic for TT-rider, and that he was gifted the frame by that rider. However (even though I had heard of 650c being popular with TT bikes back in the day) I never considered to measure the black frame, due to the fact that the blue is 700c.
    However when you look at the two frames side by side, the difference in the placement of the brake-bridge is clear.

    Life goes on, i can either: 1) sell the frame or 2) source a 650c 1 1/8 fork and wheels – I can use the new fork for blue Rex.

    Some part of me still want to build the frame and have a part of old school bike “tech”.

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  • To help me overcome my disappointment over the now scrapped Principia project, I’ve picked up my old Orbea track-frame. Gonna put on a new cockpit (Thomson Elite), new tires and remove some links from the chain.

    Might need a new headset due to the fact I lost the compression ring, and rode without one for a while (stupid)..

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  • There is a Principia thread on here if you fancy asking questions there.


    I have a Rex, a TT2 and a track bike, and also several 650c bikes (not Principias).

    I would suggest keeping an eye out for 650c bits, they aren't common, but do pop up from time to time, there are some bargains to be had with 90s TT tech, and it is normally in decent condition despite its age

  • Fitted some tan-wall tires – I’m pretty pleased with the result. Think its going to look pretty good with the Thomson cockpit.

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  • I’ve actually used that thread for both inspiration and knowledge (so it’s kinda sad the first Principia turned out so ugly, so many nice Principias in that thread and on this forum in general…) . I’ve still got the frame, but it seems quite hard source a 1 1/8” 650c fork (I can see that Wiggle sells a 3t funda 650c fork). I’ve never tried a 650c bike before, so I really don’t know what to expect when/if I build it.
    But your post kind made me want to build the bike. There is a pretty good deal locally for som HED alu/carbon clinchers 650c, then I just have to source a fork….

  • I realise you aren't in England, but there is a 3t funda here. 650c bought in error


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Oli's Bike shed (Twin Principia REX's, Felt, Scott, Orbea & Ridley)

Posted by Avatar for Oli-from-DK @Oli-from-DK