Converting my Dahon Vector in to a 20-speed Road Bike

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A Dahon Vector conversion to 20-speed mini-Road bike

This is a guest post, written and shot by Derrick Zulueta. You can get your own Dahon Vector here.

Dahon vector conversion

Greeting! I bought my Dahon Vector P8 from NYCeWheels five months ago as a birthday gift to myself. I used it for about 4 months before I decided to convert it into a mini-road bike.

Four months gave me enough time to evaluate what I need to do for the upgrade. It took me one month to complete my project since all parts were sourced online.  The installation of aftermarket parts are not much different from a regular bicycle parts (except maybe for handlepost and front derailleur), so I won’t go into detail about that, instead, I hope to share some insight on how I dealt with workaround to make it functional.

The Dahon Vector P8 before the conversion:

Dahon vector conversion

This is a challenging project since I never had a road bike, or any prior experience on customizing a bike. I really don’t know what to expect, but my goal is clear – to convert my folding bike into a mini-road bike.

After months of research on prospective parts and their availability, I watched several tutorials and know-how in YouTube, and I came up with an ideal list of components to use in the hopes of having a performance improvement as well during the conversion, namely: dropbar, brifter (integrated brake and shift lever), 20-speed drivetrain, and a bigger 451mm wheelset.

Mounting a Dropbar

Most Dahon folding bikes came with adjustable Radius Telescopic handlepost which folds INSIDE of the frame. My goal is to keep the ability of the handlepost to fold even when installed with a dropbar. I managed to find a handlepost called Radius V T-shape which folds OUTSIDE of the frame. This handlepost is very rare in the US, it come as stock handlepost from a few selected Dahon model like the MU SL. This handlepost has a length of 330mm (13 inches) and a clamp diameter of 25.4mm. The handlepost is also angled towards the seatpost when installed as opposed to the stock Radius telescopic handlepost.

Newer dropbars has a clamp diameter of 31.8mm. I bought the FSA Energy Ergo with drop of 150mm, and I found this to be ideal with my height and reach on aero position (your preference might be different). In order to mount the dropbar to the Radius V T-shape handlepost, you’ll need a bar clamp from ControlTech which has a mounting holes for 25.4mm and 31.8mm. I also installed a stem extender called Aber Halo which moves the dropbar away from the seatpost by 50mm. The handlepost is the easiest to install, you’ll just need a 10mm allen key wrench to secure it into the headset.

Selecting the Drivetrain

The drivetrain set is the most expensive component for this project, and my challenge here is selecting the right drivetrain without overspending on the budget. I chose the Shimano 105 Road groupset  because it has the features of the top-end model at an affordable price. This is a commonly used component set on a lot of top road bikes and training bikes, it is exceptionally smooth, very durable and reliable group set. The set includes the Shimano 105 STI Lever, Shimano 105 standard crankset 53T/39T HollowTech-II, FD-5700 front derailleur, RD-5701 rear derailleur short cage, CS-5700 10speed cassette 11-28T, and CN-5701 10speed chain. As for the bottom bracket, the Vector frame BB shell size is 68mm English Thread. I chose the Shimano Ultegra SM-BBR60 Bottom Bracket because it is super light (only 77grams), and has better seal.

Stage 1 Assembly

I don’t have my own garage because I live in an apartment so I did everything in the kitchen!  It is IMPORTANT to use a proper set of tools, don’t use anything that is found in the kitchen. In this photo, the FSA dropbar, STI brifter, Radius V handlepost, and the double-chainring crankset have been installed.

Dahon Vector conversion

Wheelset and Tires availability

The standard 20” wheel measures 406mm. Another version of 20” wheel measures 451mm. Majority of folding bike frames will need a 130mm wheel hub for the rear, and 74mm for the front hub. There’s a very limited selection of 451mm wheelset that has those hub sizes. In US, ControlTech offers those wheelset in 6061AL alloy and 3k carbon version. The alloy version costs just a little bit over 200 bucks, while the carbon version costs almost a grand. The 451mm wheel will have a performance gain of 5 gear inches on 55T/11T gear ratio over the standard 406mm wheel, so for practicality, no question asked I bought the alloy version. There’s also not much of a big difference as compared to the weight of the carbon version as well other than looks. The ControlTech 451mm wheel with tires installed weighs around 1.6kgs, and is 600 grams lighter than the stock Kinetix Comp wheelset of the Dahon Vector.

The tire selection for 451mm wheel is also limited in US. You’ll be limited with these options:

Schwalbe Ultremo ZX 23x451mm (foldable)

Schwalbe Durano 28x451mm (wire bead)

Panaracer Minits Lite PT 451mm (foldable). Available is 23, 28, and 32mm size.

I chose the Panaracer 451x28mm size. The panaracer is designed for long mileage, and is good for touring. I believe they’re the best value. As for the tube, the ControlTech 451mm wheel will work on tubes with presta valve, otherwise you’ll need to drill bigger hole for schrader valve.

Stage 2 Assembly

Dahon vector conversion

The wheels, rear derailleur, and sprocket have been installed.

The Dahon Vector came with a proprietary Neos rear derailleur, it does not come with a standard rear derailleur hanger. The good news is, there’s a company here in US that manufactures a wide variety of rear derailleur hanger. They’re called Wheel Manufacturing, and the RD hanger for the Dahon Vector is model #27.

Dahon vector conversion

Short reach and Long reach Caliper Brakes

I made a mistake when I bought two SHORT reach caliper brakes (Shimano 105 brake caliper) for my project, and I learned it the hard way.  In terms of reach, the short reach brake caliper essentially should work on a larger diameter 451mm wheel because the rim will now be closer to the brake pads. The Shimano BR-5700 brake caliper which has a reach of 39-49mm has no issue when installed on the front, however the rear will need the LONG reach. The only way to mount a brake caliper on the rear is to use the Tektro r559 long reach 55-73mm. They’re good quality caliper brake but the brake pad is so-so, so I replaced it with a nicer pad from Koolstop.

Brake caliper nowadays are being offered for recessed mounting. The Dahon Vector frame and fork do not have a recessed mounting. I found this wonderful article from SheldonBrown which guides me through the installation process.

Helpful article from SheldonBrown:

Mounting recessed calipers on frames that do not have recessed mounting

For Rear: Front calipers for recessed mounting have bolts that are long enough to mount in back, if you substitute the appropriate washers and a 6 mm nut.

For Front: Here are 3 options:

1. Drill out the back of the fork crown (8 mm or 5/16 drill bit). This is actually quite easy to do with a handheld electric drill, since you’re only enlarging an existing hole. That’s it if you can get two front calipers. Sometimes, you may have to deal with a pair of brakes, with one long and one short bolt. If you used the long one in back, you can use the short one in front two different ways:

2. Drill out the back of the fork crown and use an extra-long recessed nut. These nuts are commonly available for use in carbon fiber forks.

3. Use the short recessed nut, but don’t put it through the back of the fork. Instead, push it up into the inside of the steerer from the bottom. You can reach a 5 mm Allen wrench in through the hole in the back of the fork, and poke the short caliper bolt in from the front. You may need to shorten the recessed nut slightly to get it to fit inside your steerer.

I have bought two front calipers with long center bolt(Shimano 105 Front and Tektro R559 front) and a pair of concave washer to help secure it to the frame and fork. I went option #3 for the front so I won’t have to drill holes on the fork.

Dahon vector conversion

Tricky Front Derailleur

The Dahon Vector frame doesn’t have a mount for front derailleur. The seat tube outer diameter of the Dahon Vector frame is around 40mm (don’t know the exact measurement), so you’ll basically need braze-on type front derailleur which is only available in a road groupset and a clamp/mount with an inner diameter of 40mm. I chose the Shimano front derailleur FD-5700 which belongs to the 105 groupset, and the clamp is a LitePro K-Type Braze-on adapter which is available via eBay. It requires a good amount of dexterity to precisely mount the FD so the chain guide is positioned between 1-3mm above the biggest chainring (as per Shimano spec) to achieve a smooth shifting. The FD chain guide needs to be perfectly aligned in parallel with the chainring as well to avoid rubbing with the chain when shifting to the biggest or smallest cog.

The Dahon Vector neither have a cable guide nor a barrel adjuster for cable tension. The LitePro FD clamp has a built-in cable stopper though. I used zip tie to secure the shifter cable, and I ran the shifter cable underneath the bottom bracket shell all the way to the cable stopper.

Stage 3 – Final Assembly

Dahon vector conversion

So here it is with the brake and shifter cable installed. I test folded it to make sure the cable is long enough to bend around the frame without excessive cable tension. I’m using a Jagwire Road Pro stainless steel cable and housing for brake and shifter.

This DIY project is really fun (and costly too), and I learned a lot from the experience. I know a lot of folding bike users have asked the same question about customizing their bike, and I hope to share this project to the DIY community ☺

List of aftermarket parts

The bike was literally stripped down. The frame, fork, headset, and seatpost clamp are what’s left on the original parts.

  • Wheel – ControlTech ISO451mm AL6061 clincher wheel (hub size 130mm rear and 74mm front)
  • Tire – Panaracer Minits Lite PT Foldable Aramid bead 451mmx28mm
  • Tube – Sunlite Tube presta valve (451mmx28mm)
  • Brake/Shifter – Shimano 105 ST-5700 Lever
  • Crankset – Shimano 105 standard crankset 53T/39T HollowTech-II
  • Front Derailleur – Shimano 105 FD-5700
  • Rear Derailleur – Shimano 105 RD-5701 short cage
  • Sprocket – Shimano 105 CS-5700 10speed cassette 11-28T
  • Chain – Shimano 105 CN-5701 10speed
  • Bottom Bracket – Shimano Ultegra SM-BBR60
  • Shimano 105 BR-5700 brake caliper (front) – short reach 39-49mm
  • Tektro R559 brake caliper (front) – long reach 55-73mm
  • LitePro Braze-on K-type adapter for front derailleur
  • MKS FD-7 folding pedal
  • Brake and Shifter cable – Jagwire Road stainless steel cable and housing with L3 teflon lubricated
  • Radius V T-shape handlepost
  • Aber Halo Stem extender
  • ControlTech bar clamp 25.4mm-31.8mm
  • FSA Energy Ergo Dropbar
  • Lizard DSP bar tape (two-tone)
  • Biologic seatpost 33.9mm PostPump 2.0
  • Fizik Aliante Gamma saddle