Interbike Custom Bikes Update IV (Worlds Lightest)

*** The Final Update on The Worlds Lightest Bike is Posted.

Back again for more interbike updates.  As mentioned earlier, we were fixed on 2.5 projects but now it’s expanded to the usual 4+.  So for right now we’ll look at the newest project which was tossed at me and I just couldn’t turn it away.  I’m sure many or most of you have seen Gunter Mai’s world record bicycle at 6.55 pounds.  We loved that bike, and only had a few complaints about it.  Now it’s found it’s way here, at least part of it has and we’ve been given the chance to make some changes.  The new owner of the bike, Jack has sent it our way and we’ll work together to see if we can improve on it, in our opinion.  If you want to see the previous complete version of the bike you can find it here:

Gunter had gone to great lengths to get his 2.97kg weight so really there is very little to improve on in my opinion.  We did want to outfit it with a full range of gears as well as q/r skewers since the bike should ultimately be a hill climb racer.   So let’s take a look at what Gunter had, what we got from him and the changes we’ve made so far.

The foundation for the project was a full custom Spin. One of the most meticulously hand crafted frames I’ve ever seen.  Bottom bracket bearings are a slip fit with cups molded in.  Headset bearings cups are molded in and a reduced diameter upper accepts the Extralite micro bearing without a carrier of any sort, saving quite a few grams.   Down tube shifter bosses were put on the bike, but on the headtube instead of the downtube.  Claimed weight was 642.5grams, but my scale says it’s 643.9  It’s certainly possible that it’s gained 1.4 grams worth of road grime from the 1000’s of miles of use this bike has already seen in the last year.

The fork is a one off custom hand made by Thomas at THM.  Claimed weight of 185.9grams.  On our scale, it’s exactly that as well.  Considering that a production version of this fork is already the lightest fork available and weighs usually around 225 grams cut, there really isn’t anything to do here.  So like the frame this remains unchanged.

The bar/stem came complete and I knowing the weights of the individual pieces, I didn’t see a need to disassemble it yet.  So for now the complete package here is 264.6grams.  That includes, handlebar, stem, brake levers, brake housing, and bar tape.  Once again all one of a kind custom made.  111 gram custom Schmolke bar, 54gram custom NoRa stem as well as heavily modified brake levers built from what used to be a Campagnolo ergo shifter.  Once again absolutely nothing to improve on here.

Headset.  Custom built specifically for this bike the stock headset featured a ceramic hybrid lower and an Extralite micro upper with custom made wedge.  No lower race is included because the fork accepts a press fit directly onto the steerer/crown.  The original headset came in at 23.4grams.  We kept the upper bearing and wedge but replaced the lower with a Kcnc DLC coated ceramic hybrid from the Morion M1 which dropped the headset almost a full 5 grams.  Maybe not a huge savings but as a percentage of the total that’s quite an improvement.

Downtube shifters made by Bernhard at B-T-P. Certainly not much to save here, perhaps a fraction of a gram could be shaved off by reducing the size, but to keep the functionality I think they should remain unchanged.  Claimed weight was 9 grams we find them 9.2 grams.

Here is where we suffer our first penalty.  The original Gunter derailleur was a scant 28.5 grams.  Our plan is to eventually replace it with a 35 gram BTP derailleur, but lead times are likely to prevent that from happening before interbike.  So as a stop gap fix we have our in house tuned Campag Record derailleur at 49.9 grams.  Already we’ve managed to make the bike almost  1% heavier.

Here again we gain weight.  In keeping with the spirit of a bike that can be raced in hill climbs we have to face the likelihood that it will in that process find some descents.  Shaving the brakes to make them lighter isn’t really an option.  So we went with the lightest things available to us in semi-stock dress.  The Ax Orion Premium fitted with BTP race pads and btp cordz adapters reduced the stock weight from 145gr. down to 103.5gr.  However Gunters previous brake was 71.6gr complete.  That’s a gain of 31.9gr, and probably the biggest one of the project.  That’s over 50gr gained so far.

The seat collar is yet another BTP product.  Claimed at 2.9 grams and coming in on our scale at exactly 2.9 grams we see no way of improving on this and retaining some sense of durability, so it stays unchanged.

Another piece that came with the bike that will remain unchanged is the custom one piece, Schmolke TLO / Tune Speedneele, seat and seatpost combo.  Covered in the same foam that works for handlebar tape this combo unit weighs an incredible 74.9grams on our scale, though the claimed weight was 75.1grams.  We see no reason to make any changes here.

Finally it’s time to save some of that weight we gained with the derailleur and brakes.  This is one possibility.  It’s a crank from Rico at Myth.  An early prototype and one of only a couple in existence.  At 281.4gr complete w/bb it’s 16.6grams lighter than the previous THM from this bike.  There is another possibility which we won’t show unless it arrives in time for the show.  Hint: it is produced by the same company that makes at least one other item on this project.   Chainrings have finished production but have not arrived yet and will be about 6 grams lighter than the previous rings, more on that once they arrive.

For the biggest chunk of our weight savings we’ve got new wheels for the project.  These wheels currently sit on the bike and have saved about 3 grams over their weight since we built them.  These are still not the final product we have an idea that could still take a decent chunk of weight from them.  The previous Lew wheels were a much deeper profile and with that came a heavier weight at 709.6gr.  That’s a savings of just over 100 grams.

So as things stand now we are making the bike lighter, but with several changes still pending and most of them adding weight to the bike we have to work on a few other areas for saving weight.  It would be nice to see this bike go below the 2.8kg mark, but right now my estimates put it falling just shy of that goal, but I think I’m being conservative.  More updates to come as more parts arrive.

10 comments on “Interbike Custom Bikes Update IV (Worlds Lightest)”

  1. Phil Gandini says:

    This is a crazy project! I love it. And Jason has put his usual level of detail into the presentation of the project. So, does this bike now reside in the US, rather than the EU? Nice.


    1. Phil, yes the new owner is in Colorado now.

      Travis, this is just an update when the bikes are ready for Interbike we will have detailed images taken of everything. Not too much longer to wait! 🙂

  2. Travis says:

    Could you post better pictures of the brake levers?

  3. Ian Pederson says:

    When I first saw those AX wheels the first thought that popped into my head was “I bet those would look great on Gunter’s bike” and now they are. You guys truly have a dream job.

  4. Sebastian says:

    Some parts are too heavy. 😉

  5. Larry Frostman says:

    Great , now I can skip the diet !

  6. Jason Martin says:

    Guys…. I REALLY want to make my next Mountain Bike to be a DI2 bike. What would I need to do? I can source most of what I’d need locally (South Africa) but I definately need some help with remote shifters/derailleur cages,etc.

    Can you help me?

    PS. Your Crumpton bikes are gorgeous!

  7. Tim K says:

    @jason martin… Just ride Singlespeed you Pansy 🙂 it saves weight and there are no excuses…

    P.S. I am also from South africa and ride a Custom made TI singlespeed mtb ask jason how pretty it is!

  8. Stephen says:

    Interesting the things males waste their time on… There is a bike that comes in at 3.6 oz, all made of unobtanium it seems.

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