Folding Bikes - new Folding Fixed gear

I have been needing a folding bike for when I travel to various national psychology (my career) conventions. Other than my tandem, I always ride a fixed gear. So, for by birthday this year, I decided to build a fixed gear folding bike. I finally finished putting it all together.

By the way, for those who may not know, a fixed gear bike is a bike with only one gear that is essentially fixed to the hub. There is no freewheel and therefore no coasting. You will notice that there is no rear brake. This is because I can slow down the rear wheel by slowing down my cadence. You might also notice that the drive chain is on the left side. This is because the cranks are some spare tandem cranks I had laying around. On a fixed gear, the drive can go on either side.

The bike is a Dahon Boardwalk S1. Modifications are as follows:

1. Chopped the original bar stem (with welded straight handlebar) with an angle grinder and put on an adjustable headless stem. This involved hammering in a star bolt and tightening everything down.
2. Installed Nashbar cowhorn bars with a Tektro reverse brake lever.
3. New cranks. removed old cranks (square taper), and installed 175mm Shimano 105 tandem cranks.
4. New rear wheel. I build up a rear wheel with a flip-flop (fixed-fixed) track hub and laced it to a new rim. It took a little bit of work to get the spacing right (116mm). I had some extra track cogs from my other bike so I installed the smallest I had available, 15t.
5. New chainring. I don't remember what the original chainring was, but the biggest I had around was a 52t. This was entirely too small for me (I tend to ride a high gear so that I can keep up with the fastest group on training rides). I bought a Vuelta 60t chainring (typically used on recumbents). Much better.
6. New saddle. The original was terrible. Unfortunately, the one I bought isn't all that great either, but it is certainly better.
7. New tires. Actually I already some 20" X 1.5 Kenda High Pressure tires (100psi) from a bike trailer I built. I put these high pressure tires on the folder and put the boardwalk tires (similar, but lower pressure), on the trailer.
8. Added lots of reflective tape.
9. clipless pedals (speedplay frogs). I always ride clipless. These pedals are shared with my other bike.

Here are some pictures. It rides great. Feels very similar to my other bike, just a little lower to the ground. I might want to do something about the seatpost eventually because it is about 1.5 inches above the max line (I'm 6'1"). I could get one of their extending seatposts....maybe later. It should be perfect for my traveling and I might even start using it for all my commuting.

http://www.bobbykizer.com/boardwalk_fixed1.JPG

http://www.bobbykizer.com/boardwalk_fixed2.JPG

http://www.bobbykizer.com/boardwalk_fixed3.JPG

Always nice to see another fixie foldie! Welcome to the forums - and what a nice bike.
I do worry slightly about the seatpost being over extended - I hope it doesn't overstrain the seattube in the frame. I've got a couple of folding fixies myself - They are great fun - you do right to be an evangelist - see the links in my signature.

I'm a bit concerned about the rear cog if it's a standard fixie hub. Sounds like you are totally dependent on the lockring to prevent the cog loosening when pedalling forward. I thought you needed the lhs BMX hubs for that setup.

Braking of course will be 100% :)

Nice bike.

Nice bike, that thing looks mean.

Welcome and Thx for sharing - inspiring sweet mod. I always thought the bordwalk next to the swift would be perfect for a fixed gear
:-)

In response to datako, you are correct that it does rely on the lockring, but because the lockring is threaded left, it would essentially tighten when pedaling. I have been running my other bike like this for over a year without any problem.

Nice work, but if that were my bike, I'd be lopping off 3-4 inches of the handlepost!

Remarkably stylish. The skinny frame tubing looks really appropriate with the upgrades/mods you've done.

Looks nice!

So are the pictures flipped or are the chainring and cog on the left side of the bike?

A folding fixed gear ?

That is ridiculous.

:D

pine cone- the chainring is on the left side (see the original post).

fear & trembling. I wish I could cut some more off, my other bike has a lower slope (about 4 inches lower than saddle. Unfortunately, the steering tube/stem is tapered. I cut it as low as I could to still get a 1 1/8 inch stem over the tube. I know that there are other parts that would work better that I could buy from gaerlan, but this works just fine for now.

I've got a boardwalk S1 as well. I thought about doing this a couple times, but one thing's always worried me: The handlepost tapers. How do you get the stem to hold on securely?

pine cone- the chainring is on the left side (see the original post).

Sorry... missed that the 1st time around. With your flip/flop hub you will never have to worry about it coming unscrewed while stopping,

I have unscrewed one rear cog on a fixed wheel (a bit of a surprise :twitchy:), but I normally have brakes on both wheels so it's not a big deal I love fixed wheels and love folders but haven't combined the two yet. Maybe next year...

Any guess on total bike weight in ready-to-ride condition?

pine cone- the chainring is on the left side (see the original post).

fear & trembling. I wish I could cut some more off, my other bike has a lower slope (about 4 inches lower than saddle. Unfortunately, the steering tube/stem is tapered. I cut it as low as I could to still get a 1 1/8 inch stem over the tube. I know that there are other parts that would work better that I could buy from gaerlan, but this works just fine for now.

I'd get a quill stem - cheap and adjustable. That's how mine is bodged:

http://farm1.static.flickr.com/19/116282387_414643fdab_o.jpg

Looks really nice djembob! :thumb: I'd love to try something like that one of these days.

The Dahon Broadwalk is one of my favorite. Simplicity and light. A classic.
Great job for the fixie

apaclypse-
Good question about the handlepost. I actually tried a quill stem first but the quill stem was too narrow for the opening of the handlepost. This led me to try putting a 1 1/8 stem on the outside, like a threadless fork. This worked great. To secure it well, buy a "star nut/bolt assembly" from a bike shop or online retailer. This nut has a special locking washer thing on it that has tabs sticking out (kind of like a star). The nut is hammered in by threading it onto the bolt and hammering in the fork or in this case, handlepost (bike shops actually have a special press for doing this, but they told me that it works fine to hammer it carefully). Then simply take the bolt back out, slide on your new threadless stem, put on the top cap, tighten the bolt, align the stem with the front wheel, tighten the pinch bolts.

It was actually very easy, and is very secure.

http://www.sheldonbrown.com/images/starnut.jpg http://www.sheldonbrown.com/images/headset-threadless.jpg

@djembob02

I'd keep an eye on the top of the seat tube area for cracks/fractures. With your seatpost at that height you're putting a lot of leverage through the frame. I talk from experience...

If you grind off more of the handlepost a 1 1/8 quill will fit as the post tapers out...What's more, it will stiffen up the front-end.

Yes, I actually realized the the seatpost is even higher than I had thought. I am ordering the extendable seatpost. It won't look quite as clean, but I guess function is more important than looks.

Regarding the stem, I will keep that in mind. If I begin to experience any problem, I might try that. I actually was not aware that 1 1/8 inch quill stems were available. I just did a quick search, and it would certainly work.

One last thing, someone asked about the weight. It weighs 21 pounds.

since your drivetrain is on the left, won't the rear hub threads be opposite what it's supposed to be?

You might also notice that the drive chain is on the left side. This is because the cranks are some spare tandem cranks I had laying around. On a fixed gear, the drive can go on either side.

Nice. This also gives you a smaller fold with the drive train tucked in the middle of the fold.

I don't know why Dahon just doesn't make their bikes fold to the right so regular drive trains have this advantage.

Nice. This also gives you a smaller fold with the drive train tucked in the middle of the fold.

Yes! I just realized that. Now I'm thinking of LHD myself...


I don't know why Dahon just doesn't make their bikes fold to the right so regular drive trains have this advantage.

Because the handlepost/bar would then bump into the derailleur when folded.

Ooo... interesting "mods".

I think you are OK, with the seatpost IF, the bottom end of it is down near toptube(?) / chainstays ... if you only have enough in the frame, where just the clamp is around it. Then you are def. playing wth fire . ... atleast thats the way it was explained to me ...

Why do people keep asking about the LHD ? : o)

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did you find a magic ratio and/or use a half link to achieve chain tension?
nice ride man!
I am srsly thinking of converting my joey to fixed, even though I would have to drop the chain to fold it every time....
anyways, im ooking at the ENO White eccentric hub, so im interested in how you got your chain right

edit: ooh I see, horizontal dropouts! never mind :)

Awsome bike. Nice done.

Must be nice and light, what is the weight?

cmcanulty, the OP said in an earlier post that it's 21 lbs. Not bad.

Djembob02, do you happen to have any pics of the Boardwalk folded? It would be cool to see it especially with the reverse cranks.

Purdy sure. The dahon curve d3 ( 16" ) DOES fold to the drive side.

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