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  1. #1
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    Downtube 9 folding modification.

    I recently purchased the new model downtube 9 (front suspension). It's a very smooth ride, and meeting my expectations very well. It's also my first "real" bike; I'm not a very serious or experienced cyclist.

    I live in a small apartment, and I'm using it for commuting, so it spends lots of time folded up (at office and at home). This is where the problem comes in. I ride in a very upright position (I'm not a very sporting cyclist and lack the flexibility- especially in the neck). I've adjusted the brake levers, shifter, bar ends and handlebar angle to fit my riding posture. This has made the handlebars and controls very "long" front-to-back. Since the handlebars fold between the wheels, this makes the folded package significantly wider. I'm trying to reduce the width when folded.

    I think that rotating the lower stem can put the handlebar hinge on the other side of the bike- making the handlebars lay "outside" of the fold. Noting the image below, the handlebar folding joint hinges towards the rider (well, 45* to the side), so that the handlebar rotates down beside the 'rear' edge of the front fork.

    My first thought was to rotate the lower stem 90*. This would put the handlebar folding joint hinge 45* to the other side towards the rider. This would put the handlebars on the outside. If you look at the picture, though, you will see the problem with this plan: the lower stem joint tilts forward around 5* from the steering axis. The result is that you have a handlebar tilted 5* to the left. I took the bike to my LBS to try out this experiment and there was much snickering at the funny angle.

    My second though is to rotate the lower stem 180*. This would also allow the handlebar to fold on the "outside" of the wheels when folding. It will also tilt the handlebar 10* towards the rider (relative to the original position).

    What are your thoughts? I'm a bit concerned about rotating the lower stem from a safety standpoint. I haven't considered if it ruins the bicycle, structurally speaking, to essentially mount the stem backwards on a threadless headset. I also don't know how the handlebar stem's 5-10* tilt towards the rider will effect handling. And finally, I haven't seen any folders that swing the handlebars on a hinge *away* from the rider- it is always hinging towards the rider. Is there any concern that if the latch fails, the hinge away from the rider will facilitate flying the rider over the handlebars?



    Side note: Yan was most helpful with my purchase. I live relatively close to the downtube brick&mortar store and Yan was very accommodating with my need to test-ride it before purchase. Gold star there!

  2. #2
    jur
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    Handsome bike.

    I wonder if you should stick it out for just a while with the existing setup. I remember very well when I started riding, I couldn't get upright enough. I wanted to sit up and beg, and had no neck flexibility. But in a fairly short while things improved, quite drastically so.

    So do some gentle neck stretching exercises along with your riding, eg when you get to work. Tilt the head forwards, backwards, sideways and turn as far as it will go, hold for 15 seconds in each position. Push a little and pretty soon you will be amazed at the improvement.

    Slowly over time, also start lowering that handlebars until eventually you end up with the bars roughly level with the saddle.

    Before long you will start thinking about having higher gears. (That requires a bigger chainwheel. I am on a 60T chainwheel these days.)

    If nothing works, then there is always the option of installing an Aberhallo stem (thorusa.com).
    My folding bike photo essays www.dekter.net/

  3. #3
    jur
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    Sorry, I never addressed the original question - of trying to reduce the folded width.

    It helps a huge lot if you can identify exactly why it will not sit neat and flat when folded. It may be brake levers, bar ends or other items interfering with the fold. I found that by fiddling with the handle bars' height when folded is crucial. Lowering or lifting them up when folding may have the desired result that it slots neatly in an empty space. I remember my Yeah bike, that required the bars to be pulled up a bit when folding, which put them close to the ground when resting, between the wheels, with nothing interfering. Minimum folded width resulted. Pedal position is also important.
    My folding bike photo essays www.dekter.net/

  4. #4
    Eschew Obfuscation SesameCrunch's Avatar
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    Quote Originally Posted by jur View Post
    Sorry, I never addressed the original question - of trying to reduce the folded width.

    It helps a huge lot if you can identify exactly why it will not sit neat and flat when folded. It may be brake levers, bar ends or other items interfering with the fold. I found that by fiddling with the handle bars' height when folded is crucial. Lowering or lifting them up when folding may have the desired result that it slots neatly in an empty space. I remember my Yeah bike, that required the bars to be pulled up a bit when folding, which put them close to the ground when resting, between the wheels, with nothing interfering. Minimum folded width resulted. Pedal position is also important.
    Or, the entire handle-post can be lifted out and inserted in between the folded frame. It looks like there's a quick release for the post.

  5. #5
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    Quote Originally Posted by jur View Post
    Handsome bike.
    Thanks much!

    Quote Originally Posted by jur View Post
    I remember my Yeah bike, that required the bars to be pulled up a bit when folding, which put them close to the ground when resting, between the wheels, with nothing interfering. Minimum folded width resulted. Pedal position is also important.
    The bar-ends add some length to the handlebars, so pulling them to where they are past the top stays (with the brakes) and hub projections actually has the bar-end touching the ground in "front" before the bottom bracket does. This is when folded, of course. The opposite works a little bit better- shortening the handlebars as much as possible puts them above much of the workings on the rear wheel.

    Quote Originally Posted by SesameCrunch View Post
    Or, the entire handle-post can be lifted out and inserted in between the folded frame. It looks like there's a quick release for the post.
    That's right- but there's also a retaining pin that keeps the handlebars from being extracted beyond safe minimum insertion or rotating. I pulled the bolt to extract the handlepost, and this does give a great fold. It's a bit much to do every time I fold though (couple times a day) since it requires an allen wrench.

  6. #6
    Senior Member JosephLMonti's Avatar
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    Quote Originally Posted by jur View Post
    ...there is always the option of installing an Aberhallo stem (thorusa.com).
    +1

  7. #7
    jur
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    I don't think rotating the stem 180deg will be a problem. If the hinge folded spontaneously, you actually would be better off since pulling towards you closes it. Does the hinge have a safety backup mechanism?
    My folding bike photo essays www.dekter.net/

  8. #8
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    Quote Originally Posted by jur View Post
    I don't think rotating the stem 180deg will be a problem. If the hinge folded spontaneously, you actually would be better off since pulling towards you closes it. Does the hinge have a safety backup mechanism?
    Good to know. I figured that if something shouldn't be mounted a certain way, it wouldn't fit/not turn snugly/other mechanically-obvious failure mode.

    The hinge is... Well it isn't like a dahon-style hinge (with some type of levered system that locks into place)- it is very similar to brompton hinges. The two parts of the hinge fit together then a wedge is jammed into their intersection with a screw-handle. It doesn't have a secondary safety latch like dahon's do, but it takes a very deliberate effort to fully unscrew the hinge so that it will open.

  9. #9
    Senior Member jobtraklite's Avatar
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    Quote Originally Posted by SesameCrunch View Post
    Or, the entire handle-post can be lifted out and inserted in between the folded frame. It looks like there's a quick release for the post.
    I hadn't thought of that. Sounds like a good idea. My only complaint with my Dahon MU P8 and Speed P8 is the fold. By the time I fine tune the the handlebars' height and angle so they don't get in the way of the fold or in the spokes so I can roll it, I might as well pull it all the way out.

    Do you find that the bars will stay in place while you roll it, or do I need to bungee them in place? As it is now, I need a bungee to keep the fold; but with your system, the magnet might be able to do its work and I can use the bungee to hold the bars in place.

  10. #10
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    I performed the modification and did a 180 on the stem. The handlebar now folds over the front. The barends protrude out the side a bit, but it solved my original concern which was tightening up the "footprint" defined as parts-of-the-bike-touching the floor. The handlebars are now free to have more accessories attached without worrying about damaging it when folding the bar down between the wheels casually. The usual bungee solution is employed to hold it all together (no magnetic coupler on the bicycle... yet!). This solution also leaves me easier access to rolling when folded http://www.bikeforums.net/archive/in.../t-612570.html since I don't have to open up the wheels to get at the handlebars.

    I think I'll still take the handlebars out when the bike goes into the trunk, as putting it on its side currently requires me to choose between plopping it down on the folded handlebars or on the derailleur.

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