Bicycle Design

A little Birdy

This customized Birdy monocoque folder on Spinopsys caught my attention this morning. I think it is a great looking bike, but I was a little surprised when I read the weight. In his post, Philip speculates that “this particular Birdy has got to be the fastest and lightest anywhere.” Maybe so, lets see, 10 kilograms is about 22 pounds. Is that light for a folding bike? I don’t pretend to be an expert on them, but 22 pounds doesn’t really seem ultra-light to me. My 60cm road bike weighs 20% less than that without especially lightweight wheels. I know, I know; that is not really a fair comparison. This bike was not built for racing and it has front and rear suspension and pivots for folding. Still, this bike is a lot smaller than a standard bike. So I am just curious, what is the lightest folding bike out there? Is 22 pounds really superlight for a folder? Does anyone know? Maybe Walter can chime in and let us know what his fixed Friday weighs. As I said, I am no expert, but Walter’s bike looks pretty light to me.

OK, back to reading about the Tour of California. I wish I could be out there to watch the race in person. If you are lucky enough to do so, check out this excellent blog post on photographing a bike race. Great info; I found it via a Tour de France blog post.

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James

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Comments

9 responses to “A little Birdy”

  1. Marc Avatar
    Marc

    My Brompton M3L (full equiped) weights 12.4 kg. And my MTB Trek Fuel ex8 (full suspension) weights 13.6 kg.

    Reply
  2. Phil Avatar
    Phil

    I get to play around with quite a few folders James and I think this one is pretty damn light. However, maybe I could have mentioned the weight as it related to the rest of the Birdy brand.

    Still, I’m willing to bet that this is about as light as you can get form most folders.

    I should also mention that the barends are the heavy Cane Creek ergos, and the pedals could have been a lot lighter.

    Removing the barends and adding some Crank Bros Ti pedals would have made a big difference, and we did weigh ti with the pump on as well.

    Under 10 is absolutely achievable for this machine.

    Reply
  3. James Avatar
    James

    Marc, a Brompton is one of the few folding bikes I have ridden. The one I tried was no lightweight, but it was a fun bike to ride.

    Phil, I was being a bit of a smartass with this post. Of course, lightweight is a relative term and comparing a folding bike to a racer is absurd. 10 kg is certainly light for a bike like this one. Still, after seeing so many ultra light bikes lately, like the sub 3.5 kg fixed gear bike that I posted last, I can’t help but wonder what the lower limit is for different types of bikes. While I am at it I should mention that, though I really like lightweight road bikes, I have no desire to test that lower limit. Around 8 kg is light enough for me

    Reply
  4. grand_bi Avatar
    grand_bi

    The Dahon Mu SL is under 20lbs you can take a look at it here: http://dahon.com/us/musl.htm
    ; it’s the lightest folder I know of that is still in production (Dahon use to make the helios sl which was even lighter but there was to much flex in the frame http://dahon.com/archive/2005/heliossl.htm)!

    Reply
  5. bikefridaywalter Avatar
    bikefridaywalter

    First off, James, sorry for taking so long to reply. In case you haven’t noticed by the total INACTIVITY on my blog, I have been way too busy lately.

    Anyways, my fixie has gotten complicated over the years. I put on drop bars and a front brake, two levers, lights, tools, a bell, a bottle cage, fenders, a pump, an 1/8″ drivetrain, some platform pedals, and four years of road grime. So it doesn’t weigh what it used to at all. It’s up to a whopping 20#.. for a medium-sized all STEEL frame.

    The lightest we have ever built was approximately 15 pounds and it was a fully equipped road bike with a triple and STI shifters. Admittedly, it was made for someone relativelly small and light so we could shave off even more weight than I shaved off mine. The rider also had a nearly unlimited budget.

    Not enough to pay us to set up the shop to make carbon fiber or titanium, though. I think this is a goal we would one day like to achive. Needless to say, if we ever do a monocoque I’m *PRETTY* sure it will be less than 20 pounds. I mean, I could be wrong. Oh man, now *I’M* being a smartass.

    Anyways, while we’re talking about bicycle design and folders, have you seen our latest model, the tikit? We actually had a trained engineer working on making this one and it folds VERY nicely and clicks together. Get on the page, watch the videos, let me know what you think.

    Reply
  6. James Avatar
    James

    Grand Bi, Thanks for the comment. I don’t really know as much about Dahon as I should, but their product line seems to have improved a lot lately.

    Walter, a complicated fixie? Isn’t that an oxymoron? Just kidding; thanks for the reply. 15 pounds, huh. That is pretty impressive. I figured that you guys had made at least one lightweight folder for a customer. 20 pounds isn’t bad for your bike. My commuting bike is a 60cm Cannondale with a carbon fork. It could be a light bike, but with all the extra “complicated” stuff (rack, tools, lights, reflectors, heavy tires, pump, etc), it weighs well over 20 pounds. As you probably guessed, it doesn’t fold very well either.

    The Tikit looks nice. This bike seems to be geared to the commuter market where other Bike Friday’s seem to have been marketed more as travel bikes for recreational cyclists. I am glad to see this one from you guys. I only looked at the site briefly, but I tagged it so I can go back and check out the videos when I have some time.

    Reply
  7. bikefridaywalter Avatar
    bikefridaywalter

    Oh, yeah, I guess the fact that it folds should mean it should be heavier, right? Not to mention the fact I’m sure your Cdale uses some material lighter than steel.

    On the tikit, you HAVE to watch the videos– that’s the thing I think from the design standpoint you will appreciate. The value of this bike is not necessraily the market we’re trying to reach with it, but how well it folds– which makes it all the more applicable to this continually growing market.

    Reply
  8. James Avatar
    James

    Yeah Walter, my C’dale uses some magical mystery material that is lighter than steel (I think it is the same stuff they use to make beer cans) While I’m on that subject, I probably should correct what I said earlier. I am pretty sure I could fold that bike if I tried really hard. Getting it to unfold wouldn’t be quite as easy.

    I’ll check out all the videos over the weekend (I couldn’t view them from this computer). The fact that the tikit folds really fast is exactly why I mentioned the market that it is geared toward. I am sure that anyone getting on a subway or an elevator with a bike would want it to fold instantly. You don’t want to mess with a bunch of clamps and quick releases when people behind you are waiting.

    Reply
  9. Peter Avatar
    Peter

    Walter, you guys make outstanding custom folders, but “actually had a trained engineer” working on the bike? I think the Birdy had an entire team of folks, both at RM and at Pacific.

    Regarding the weight, the older Birdy models on the Yahoo groups weigh in under 8Kg. But all their production models weigh in excess of 10Kg, so that one is light indeed!

    Would be nice to see a ultralight folder. We have to lift and carry them, after all.

    Reply

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