Initial Impressione of the Dahon Curve D3

I just bought a Dahon Curve D3… its a very stylish bicycle! The Curve D3 is the smallest folding bicycle Dahon currently sells. One bonus of owning a folding bike is that it can be made to fit kids and adults alike.

Having owned a Speed Pro V, I knew that Dahon doesn't sell junk… they sell quality. The narrow high pressure Comet slicks are great on pavement but you feel every bump in the road which is the price you pay for speed and high pressure, energy efficient tires.

Needing a smaller bicycle for the car and an easier to fold bicycle than my Speed Pro, the Curve is the only bicycle Dahon sells with 16" tires. This saves 8" in length when unfolded because of smaller wheels alone.

The frame is also smaller. The pedals are much closer to the rear axle because of smaller wheels which means the front end can be shorter as well. For carrying around, the Curve is over 2lbs lighter than my stock Pro and 4" shorter when folded.

Red was a colour requirement from my wife. The white stripes and curving frame are very artistic. The curved styling is sure to attract attention from bicycle connoisseurs.

  There were several things I considered prior to this purchase. I suspect that the straight forks on my Pro might be the cause of dangerous high speed hill descents. At over 60 kph, high speed wobbles ensue. My next bike must  have raked forks, which the Curve does.

My Pro had no way to measure how high the seat had to be after unfolding it and it wasn't acceptable to be dealing with paint damage all the time due to parts hitting each other when folding my Pro.  Fortunately these problems seemed to have been designed out of the Curve.

The Curve does require leaving the steering stem latch unlocked to avoid paint damage but this may simply require adjusting the magnetic pads to keep the frame members further apart when the wheels are folded.

One can extend the seat post and roll it on it's wheels when folded if you have to walk a distance with it… like into Starbucks for a coffee. It's just like wheeling luggage for the most part.

The folding sequence is very simple and quick. Dahon has fixed my Pro bike's handlebar issues. A latch on the handlebar allows you to turn the handlebar so it is flush with the steering stem and it then folds flat against the frame. Nice! Much better than sticking handlebar ends between spokes!

The problem with cables catching on things when folding has also been solved in the Curve D3. I have yet to experience any cables snagging when folding or unfolding this little gem.

The 3 speed Sturmey Archer was not what I'd want on any of my bikes. Why Dahon didn't use their own sweet shifting 3 speed hub is anyone's guess. I'm never quite sure if the Sturmey will change gears when I need it to. I have to stop pedaling in order for it to shift. On hills, it is very likely that sooner or later I'll cone to a dead stop when trying to shift into low. The manual recommends shifting before hills just like the pros do.

I was never a fan of Sturmey Archer 3 speeds because of all the shifting problems my brothers had with their bikes as kids. I've already had shifting problem testing the Curve on rollers until I learned to stop pedaling when changing gears. This requires one hard pedal before each gear change so that the wheels don't stop turning.

I also found the steering extremely sensitive on indoor cycling rollers. This is probably because the shorter wheel base means the front wheel sits behind the frontmost roller. The front wheel should actually sit on top of the roller. Once the weather cooperates, I'll be glad to report on any high speed and steering sensitivity issues.

Not having a large enough gear range is often a problem with 3 speed hubs. With 77 gear inches in top gear, it's fast enough to do 20 mph which was the maximum speed of my old fifty pound one speed Black Hawk. I'd expect that Dahon will offer greater gear ratios in newer version but does one want to really go that fast on such a small bike? Guess I'll figure that out if the snow melts on Wednesday

The way I figure it, a limited gear range isn't always a limiter when training. The highest average speed on club rides is 25 kph. This sometimes means doing 30 kph to maintain that average. Using the Speed Pro V to emulate near similar performance, I used 78 gear inches and determined that 30-33 kph requires a cadence of about 90-95 rpm.

As a beginner cyclist, I used to think high gear ratios meant high speeds. I have learned that high cadence is a much better tool than high gear ratios when it comes to maintaining high speeds for long distances. Further, with small wheel sizes it is more difficult to get high gear inches without enormously large cranks… unless  internal geared hubs are used so that common sized crank and cog wheel sets can be used to generate high gear ratios with small wheels

Then, taking training into consideration, developing a high cadence takes plenty of time and practice. By limiting the high gear ratios one is forced to use high cadence to go faster. Large gear ratios often make one lazy when training for higher cadences. Having a limited low gear range means having to develop better muscular endurance. Seldom does a person think about buying a different bike to accomplish different tasks or training needs. Besides, I'd love to see Lance Armstrong speed along on one of these Curve D3s at 40 kph with his 110 rpm cadence. That would be awesome!

My first impressions of the Dahon Curve D3 is that it is one sweet machine that fits almost anywhere you want to stash it. Two Curves can easily fit in a small trunk and it is a breeze to fold up and carry anywhere with its light weight. Small wheels make for fast sprint acceleration and big tires can be deflated from 75 psi and used as shock absorbers. Some owners are reducing tire pressures from 35-55 psi depending on their weight and how rough the terrain is.

The way I look at this minibike of a bicycle, the easier it is to take with me, the more likely I am to use it. As soon as the weather cooperates, I'll be testing high speed handling and ride stability. I can't think of any traveling cyclists, especially commuters, who wouldn't improve their cycling capabilities with this unique Foldie!

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Comments (1)

  1. stevehayes13

    High speed wheel shimmy is not a function of the shape of the forks – it makes no difference whether they are straight or raked. The phenomenon can be caused by a bent (ie, damaged) fork. Other potential causes are loose headset, loose wheel bearings, unevenly tensioned spokes, uneven weight distribution (only an issue when carrying loads).

    March 27, 2011
    1. WhatILearnedAboutCycling

      Hmm… That’s weird. No fork damage, tight headset and bearings, all the spokes are tight. I take very good care of the bike. Maybe its due to most of the weight being on the rear wheel which is normal for folding bicycles?

      As yet I have no other explanation. The wheel base is close to a normal bike.

      At very high speeds the steering is so sensitive that it is hard to hold a straight line. The steering has always felt very sensitive at any speed and having raked forks that angle the front wheel forward would move the steering forces forward of the headset so they should be dampening steering oscillations. My older Dahon had raked forks on it and had great stability at high speeds. When I test the Curve D3 it should either confirm or refute what I believe to be the reason for such sensitive steering on the Speed Pro V.

      March 29, 2011
  2. dethe1974

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    March 27, 2017