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Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

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Old 07-28-07, 11:35 PM   #1
ChromePista
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2007 Dahon Jack

2007 DAHON JACK

SPEEDS 7
FRAME SIZES S (16"), M (18"), L (20")
GEAR INCHES 37" - 101"
FOLDED SIZE 38 x 69 x 91 cm (14" x 27" x 36")
WEIGHT 12.4 kg (27.3 lbs.)
FOLDING TIME 5 seconds
SUGGESTED RIDER HEIGHT S Frame (157 cm - 167 cm/5'2" - 5'6"); M Frame (167 cm - 183 cm/5'6" - 6'); L Frame (183 cm - 193 cm/6' - 6'4")
MAX RIDER WEIGHT 105 kg. (230 lbs.)

FRAME DA Series, Joe Murray design, 7005 aluminum, custom-drawn Sonus tubing, forged Lattice hinge, replaceable derailleur hanger, integrated head tube, patented ReBar technology
FORK Oversized, straight, integrated design

HANDLEBAR 6061-T6 aluminum, riser, 31.8mm oversize
STEM NVO, patented InfiniteAdjust technology, 3D forged 6061-T6 aluminum
HEADSET Dahon Fusion, Zero stack, cartridge, sealed, conical spacer
GRIPS Dual Density Kraton
SADDLE SDG BelAir RL
SEAT POST BioLogic™ PostPump, 27.2mm

BRAKES ProMax V, aluminum, linear spring
BRAKE LEVER ProMax V, aluminum bracket/aluminum lever
CABLES AND HOUSING SIS, Pearl silver housing, slick cables

FRONT HUB Formula, QR, aluminum
REAR HUB Formula cassette, aluminum, sealed
SPOKES 14G stainless steel, brass nipples, black ano
RIMS Aluminum, anodized black
TIRES Schwalbe Big Apple, 26” x 2.0”, RaceGuard puncture protection, 75 psi

SHIFTERS SRAM 3.0 Comp, 7 speed
REAR DERAILLEUR SRAM SX4
CASSETTE Suntour, 7 speed, 11-30T
CRANKSET Truvativ IsoFlo, 38T
CHAIN KMC Z50, Narrow, Noiseless function
BOTTOM BRACKET CH, chromoly axle
PEDAL VP 990-A

KICKSTAND Aluminum, Dacromet bolt
SUPPORT BRACKET Aluminum

I just received my Dahon Jack after waiting a month while it was on back order. I ordered a small sized Jack as a campus bike for my niece. It should be a perfect college bike, with a rugged design and the anti-theft folding feature. It has an excellent ride, easy to use grip shift 7 speed, full size 26" wheels, and good component quality. The mechanic at the shop was fascinated by the Shraeder air pump built into the seat post. It really is a nicely designed pump. To keep it from getting stolen, I replaced the quick release seatpost clamp with an allen head clamp.

When loading it into the car, I noticed how hefty it was. It weighs 27 lbs which is a whole lot more than my 16 lbs carbon fiber bike. I had a little trouble fitting it into the doorway of my car with the frame folded, as the unfolded bars were very wide. I also noticed that this small size Jack has the rebar integral with the hinge. In product shots of the larger sizes, there is a rebar (top tube) that joins above the hinge.

To prepare the Jack for my niece, I removed the grips and trimmed 35mm off each end of the handlebar which will fit her shoulder width better and make the bike easier to manage through doorways. This simple modification makes the bike much less cumbersome. The brake levers have adjustable reach, which I set low for my niece. The bar has an OS center and a lot of rise. I would have prefered a regular diameter bar and no rise. The stem has a notch that fits a ridge along the steerer tube sleeve. The sleeve allows the top cap to secure the headset/fork, even with the stem/bars removed for transport. The sleeve ridge allows the stem to adjust up and down or be removed, without needing to realign the stem with the front wheel. The downside is that other stems (not having the matching groove) will not be compatible.

The brakes and rear derailleur were well adjusted, but the wheels needed major tuning. I had to true them for dish, roundness, and lateral trueness. Both the front and rear hub bearings were set much too tight, but since they had adjustable cones, they were easy to set right. The BB had an old style cup and lock ring, which I also had to adjust (too tight). I rode a couple of miles on these overtight bearings, but hopefully they won't have damage. They are fairly smooth now that they are adjusted properly.

Because of the OS handle bar, the basket mount I had in mind for this bike would not work. However, there are rear rack mounts on both the drop outs and seat stays. The water bottle mount is in a strange place, underneath the down tube near the front tire. The bottle will get messy and it might be dangerous pulling the bottle out while on the move. I will have to warn my niece only to remove the bottle when stopped. By the way, stopping is easy since it has a kickstand. I realized what a nice feature this was at a crowded bike shop as I did not have to find empty wall space to prop the bike up.

The gear range was wide enough, but with only 7 speeds, the jumps between gears is pronounced. There is only one chainring, but I think this is a plus as it simplifies things. A chainring guard will keep the chain fro messing up my nieces pants. The SRAM RD and grip shift work very well together. The long chainstays, full size wheels, and kicked out fork make the bike very stable and easy to ride no hands. With the tires pumped up to the max 70 PSI, the ride was a little harsh as there is not suspension. At 50 PSI, the fat 2.0" tires should soak up some road shock. The tires are treaded road tires and not knobbies. This makes the quiet for road use, but not ideal for riding muddy trails. The saddle is very comfy. Despite being cramped on a frame too small for me and the upright poistioning, this bike was surprisingly fast and nimble. It does not feel heavy when riding it, only when lifting it.

I really like this bike and will probably order a medium sized one for myself.

Last edited by ChromePista; 07-30-07 at 10:23 AM.
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Old 07-29-07, 12:49 AM   #2
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Thanks for the write-up. I'm quite curious about this bike, and want one. (though I can't justify it) I have a nice hybrid that I ride all the time, and my Curve D3 that I ride occasionally.

Have you any idea what the differences are between the Jack and the Espresso, aside from color? I didn't compare all the specs side-by-side, as it is too cumbersome with the way Dahon's site is laid out.

But it appears the Jack has a better seat and better tires. (Schwalbe?) Maybe a better derailleur too?
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Old 07-29-07, 04:34 AM   #3
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Quote:
Originally Posted by ChromePista View Post
2007 DAHON JACK
I removed the grips and trimmed 35mm off each end of the handlebar which will fit her shoulder width better and make the bike easier to manage through doorways.
Lucky it wasn't butted. I looked at this bike before I went with small wheels. It's a great bike. I'm impressed by Dahon's component selection. They always manage the best of the least expensive componentry.
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Old 07-29-07, 08:26 AM   #4
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The Jack and Espresso have similar frames, but the execution is different. The Espresso has a comfort bike profile, triple crank, low gearing, clear finish, cushier saddle, high rise stem, and skinnier tires. The Jack has a mountain bike profile, single crank, higher top gear, menacing all black urban street fighter finish, sportier saddle, low rise stem, and fat road tires. Although the Jack has a MTB profile, the owners manual does not recommend offroad riding or jumps, and there is no suspension or knobby tires. It is more of an urban assault bike, with a minimalist design that gets the job done. A flat bar would have been much sportier, but the more upright position with the riser bar might be better for commuting in traffic. The black finish is very urban chic. It is matte black with rad gloss black splash logos. It looks much more expensive than the $400 I paid. That is now my main worry, that my niece's bike will be a target for theft.

Since I could not mount the front basket, I think I will add a rear rack with a saddle bag the converts to a shoulder bag. That will make it eaier for her to carry a U lock and books. With the long chainstays, there should be no heel clearance problems.
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Old 07-29-07, 07:31 PM   #5
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I also have a Dahon Jack. If you go to dahon.com's forum, you will see my review on it, plus some of the things I did to it. I ride it to work, and fold it under my desk.
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Old 07-30-07, 05:43 AM   #6
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ChromePista - I'd hold off on the rack before you talk to her. Luggage racks & fenders are not at all in style with the younger crowd who are not serious bikers. Maybe that's what you're after though? Make it seem like more of an old person's bike so it won't get stolen?

...just a thought.
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Old 07-30-07, 10:20 AM   #7
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My niece is a very practical person, so she wants it to have utilitarian features. When she came to visit (before the Jack arrived) she rode my wife's bike which has a front basket. We went shopping and she found the basket very useful and wanted one on her Jack. I thought she would think a basket was geeky. Because the Jack has a fat OS handle bar, I could not mount the basket bracket, so I installed the rear rack instead. It is a Transit Rack with a flat top that acts like a rear fender. I got her one Transit Metro pannier that converts into a shoulder bag that looks like what urban Gen Y people use. She can use that to haul the U-lock which weighs a lot.

There is some bike theft at her University so I installed some anti theft devices. I replaced the quick release seat post clamp with an allen key 31.8mm seat post clamp. I replaced the QR axle skewers with Hublox non-QR skewers that require a special keyed wrench. The rear skewer was a bit short, so I had to remove an axle spacer, redish the wheel, and use an old skewer nut with less recessed threads. I also printed a color photo of the bike and wrote down the serial number, so she might have a chance at recovery/claim if it gets stolen. Since it's a folding bike, I am hoping she will keep it in her dorm room at night.
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Old 07-30-07, 10:51 AM   #8
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If she's in college, she'll appreciate the basket and/or any and all luggage carrying ability, as you've discovered; most college students are smart.
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Old 07-31-07, 12:42 PM   #9
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Tell her - Don't lock the Jack up outside - it will get stolen

Quote:
Originally Posted by ChromePista View Post
Since it's a folding bike, I am hoping she will keep it in her dorm room at night.
Yeah, that is the best idea. I would never lock my Jack up outside - it is too 'cool', someone would definitely steal it.

I would add this - if she has a tail-light, it should have the quick-release knob taken off, and bolted on with a Torx (star) bolt. Same with a head light. Then at least, if she has the bike locked in front of the campus bookstore, no loser can walk by and take her light(s) off.

When I commute, I have a removable quick-release Topeak rear rack, with a 'trunk'. It works for me, but she should have a bolt-on rack. People think college campuses are full of nice, enlightened students, but there are also some losers and townies that will rip you off.

You know, I also tried to find a quick-release bolt for the stem bolt, to avoid having to use an Allen wrench to loosen the handlebars, but did not find one. Maybe it is not a good idea, because a person might accidently hit the latch with their leg. Yeah, scratch that idea.
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Old 07-31-07, 12:44 PM   #10
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She might also want one of those 'net' bungies that motorcyclists use, to put groceries on the rack. Maybe? I would say probably a really small one.
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Old 07-31-07, 08:42 PM   #11
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WoW! I wish I had an uncle like you! You really care your niece, that's nice.

I test rode the Espresso last summer and it's a nice bike. It's too straight up for my taste but changing the handlebar may have been an option. I like the bike overall with the tripple ring but I have too many bikes. You made a good choice.
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