Dahon Impulse P21 is a Dream Bike

A while ago I posted a thread about the horoscope of a new bike, a Dahon
Impulse P21, that was causing me a lot of grief. However, since the bike
had not been delivered in a rideable condition, but needed further
intervention from a cycling professional to make it road ready, I
deemed, with the help of the forum, that the horoscope could be recast
for the time I picked him up from the shop. This must optimally have
been around 11:30 on November 6th. In the event, I paid for Flyzipper's
assembly at 11:25 and rode my first few yards on him at 11:38. This was
just in time for a cycling holiday I was planning to take from 9th to
14th November in the Touraine region of France where I used to live.

This bike is a winner!

Flyzipper has 20" wheels, weighs 12 kg, and is equipped with a fabulous
21-speed SRAM DualDrive shifter - three speeds in the front hub and
seven on the rear derailleur. It is a whole new world of comfort to have
so light and small a bicycle! After a year of struggling with Behemoth,
a 20 kg Dutch monster whose geometry has never really suited me, I feel
as though I have finally come home. Flyzipper starts in a breath and
rides extremely straight. Weight on the handlebars is minimal. I was
right to choose this model with its straight T-bar handles, as this puts
so much less stress on my wrists than Behemoth's swept-back bars. My
wrists tend to start aching after only about 20 mins on Behemoth. On
Flyzipper, I rode more than 4 hours on my first big day out and didn't
even have to put on my gloves. I feel much more balanced on Flyzipper
for not teetering so high from the ground. And the SRAM is the best
shifter I have dealt with so far. All 21 gears are useable, but most of
the time, I just change between the 3 front speeds. When I have a
stretch of long, clear riding ahead, I up the rear shifter a notch or
two; when the ground is hilly or the paths are shorter or a stop-start
situation threatens, I put the rear shifter into a neutral 4th gear. I
have not yet tried the granny gears but will soon have occasion to do
so. What is great about this system is that it cuts down on needless
complexity. Behemoth has a Nexus 7 shifter, meaning that split-second
decisions have to be made between all 7 gears. With Flyzipper, there are
only 3, but each of those can be modulated through a whole spectrum of
shades when there is leisure.

I am amazed at the speed of this lil critter! He seems to be the fastest
of my bikes. Can it be that the advantage of lightness compensates for
the smaller wheels? My second outing in the Touraine was my first
accompanied cycle. My friend was on a 21-gear bike with 700mm wheels. I
was in 2/5 for most of our flat 7.5 km stint and she was in 2/7, but she
had trouble keeping up with me! We finished the circuit in just half an
hour, despite a nasty head-wind.

The Impulse P21 folds more easily and compactly than the Speed TR,
another model I considered. I worried that the addition of lights would
compromise the folding action, but this didn't happen. OTOH, the counter
did pop off when I had the bike folded. Fortunately I spotted it in time
and didn't lose it, but I now recommend pocketing it before folding. I
made a little mark on the seat-post to show how far I need to pull it
out to have the seat at the right height. As for the front bar, once
adjusted, the folding action affects neither its height nor its angle,
so this does not have to be recalculated every time.

Unlike the Speed TR, the Impulse has a chain guard, and to my delight,
after a week of stopping against lamp-posts and walls, I discovered a
small strut. It does not come with lights, but I discovered from
Behemoth that I hate dynamos anyway. I fitted Flyzipper with lights that
run on ordinary rechargeable AA batteries such as I already use for my
TV earphones and am well equipped to handle.

A few small demerits. It took me a week to figure out how to fold in the
pedals, and I reproach the manual for giving no clear instructions on
that point. (You have to push them _in_, towards their axis, then they
can be pivoted flat.) The magnetic catch that holds the bike together
when folded is rather weak and the two halves easily come apart. The
bike is extremely lumbersome to carry in its folded condition. Unlike
even the heaviest luggage which today almost always has wheels, the
Dahon needs to be hoiked and heaved over the smallest distance. I
quickly learned that, on train platforms, the folding must happen at the
last possible minute, when you are just in front of the door of your
wagon, and you must unfold the minute you alight from the train. At
Tours St Pierre station, elevators are only supposed to be used by the
disabled. I'm afraid I had to disregard this rule, because if I had
tried the stairs with that bike and my bags, I would have risked a heart
attack. (But why anyone should be expected to carry enormous
portmanteaus up and down great flights of stairs remains for me one of
the great ineptitudes of station architecture...)

The baggage rack is small and carrying capacity is limited. I used only
my one small Vaude pannier. I have various over-the-rack double panniers
but they hang too low to the ground. Also, I did nearly kick the pannier
off several times with my heel, so it could not have been any wider.
However, the Speed TR model has a special, high-set baggage rack for
touring that can be ordered for the Impulse as an add-on, should I
project a longer trip.

The most important drawback is that this bike is totally unupported in
France. Unlike Behemoth, who needs practically no maintenance, Flyzipper
has parts that rain and my weight and rougher riding could damage. I was
paranoid about getting a flat. Why are there no local sellers? Is Dahon
one of those American firms that has made a policy not to sell to "Old
Europe" out of redneck jingoism? From the fascinated glances Flyzipper
was attracting from all sides, I cannot doubt that there would be a good
market. The policy of the SNCF, the French Railway System, towards bikes
is hugely incoherent, but suffice it to say that many trips cannot be
made with a full-size bike. On the other hand, few folding models are
available in this generally bike-friendly country, and none with the
touring capacities of my Flyzipper.

I can't wait for the Spring!

EFR
Ile de France

On Mon, 15 Nov 2004 17:55:51 +0100,
Elisa Francesca Roselli wrote:
accompanied cycle. My friend was on a 21-gear bike with 700mm wheels. I
was in 2/5 for most of our flat 7.5 km stint and she was in 2/7, but she
had trouble keeping up with me! We finished the circuit in just half an
hour, despite a nasty head-wind.

Good to see you are getting on well with it (despite the horoscope
wierdness). At that speed (and maybe a little faster if there is no
head-wind) you should be fine for getting to and from work if or when
they move - as you seem to be much faster than on your old bike.

--
Andy Leighton =
"The Lord is my shepherd, but we still lost the sheep dog trials"
- Robert Rankin, _They Came And Ate Us_

On Mon, 15 Nov 2004 17:55:51 +0100, Elisa Francesca Roselli
wrote:

This bike is a winner!

*snip review*

Nice write up, thanks. Can you tell us how long it takes you to fold
and unfold the bike?


--


Email address is spam trapped, to reply directly remove the beverage.

Elisa Francesca Roselli wrote:
.....Dahon Impulse P21....... This bike is a winner!

....... Weight on
the handlebars is minimal. I was right to choose this model with its
straight T-bar handles, as this puts so much less stress on my wrists
than Behemoth's swept-back bars.......

I guess this is one clue towards sorting Behemoth - new handlebars -
assuming that bike is staying with you.


A few small demerits........... The magnetic catch that
holds the bike together when folded is rather weak and the two halves
easily come apart.

A bit of webbing or velcro strap to tie the two bits together can fix that
easily. So light and cheap that it can be left attached to handlebar or
somewhere else which is convinient.


The baggage rack is small and carrying capacity is limited.

Carradice (a UK cycle luggage maker of legends) make some bags adapted to
fit Dahon's (or, I think, have spotted a niche to sell their standard bags
to Dahon owners).
http://www.carradice.co.uk/dahon-sqr-products.htm

Digging around Carradice's site also shows an "uplift" mount for a
conventional saddle bag (wider designs rather than the longer SQR bag
shapes), which fits onto a SQR mounting block:
http://www.carradice.co.uk/sqr-products.htm





Otherwise, I wonder if its possible to get the Brompton front luggage
bracket fitted to a Dahon ? Its something which would need some thought, so
not one for someone without knowledge of both machines. If it can be fitted
there are a range of useful front bags made for Bromptons.


The most important drawback is that this bike is totally unupported in
France. ..... I was paranoid about getting a flat. Why are there no local
sellers? Is Dahon one of those American firms that has made a policy
not to sell to "Old Europe" out of redneck jingoism?

Probably as likely that French cycle shops cannot cope with unusual bicycles
? In the UK most cycle shops have little out of the ordinary.
Even so, Dahon are available in the UK, arguably easier to find than a UK
made Brompton folder.
Dahon.com suggests these are the French importer:
http://www.josealvarez.fr/public/ who in turn hint that "Bouticycle" are the
dealer outlet(s) http://www.bouticycle.com


Tyres shouldn't be too hard - Schwalbe make a range of types of the required
sizes, covering everything from extreme racing through urban sensible, to
mud-plugging off-road.




- Nigel

--
NC - Webmaster for http://www.2mm.org.uk/
Replies to newsgroup postings to the newsgroup please.

On Mon, 15 Nov 2004 17:55:51 +0100, Elisa Francesca Roselli wrote:

The most important drawback is that this bike is totally unupported in
France. Unlike Behemoth, who needs practically no maintenance, Flyzipper
has parts that rain and my weight and rougher riding could damage. I was
paranoid about getting a flat. Why are there no local sellers? Is Dahon
one of those American firms that has made a policy not to sell to "Old
Europe" out of redneck jingoism?

I can't imagine any American firm, or American Government official, ever
exhibiting anything like jingoism. You must have us confused with some
other country...

--

David L. Johnson

__o | It is a scientifically proven fact that a mid life crisis can
_`\(,_ | only be cured by something racy and Italian. Bianchis and
(_)/ (_) | Colnagos are a lot cheaper than Maserattis and Ferraris. --
Glenn Davies

David L. Johnson wrote:

I can't imagine any American firm, or American Government official, ever
exhibiting anything like jingoism. You must have us confused with some
other country...



:-)

Still, I don't think that's _really_ the problem.


--
--------------------+
Frank Krygowski [To reply, remove rodent and vegetable dot com,
replace with cc.ysu dot edu]

Elisa Francesca Roselli wrote:

Flyzipper has 20" wheels, weighs 12 kg, and is equipped with a fabulous
21-speed SRAM DualDrive shifter - three speeds in the front hub and
seven on the rear derailleur.

No, the 3 speed hub is at the back and the derailleur mounts onto it.

so. What is great about this system is that it cuts down on needless
complexity. Behemoth has a Nexus 7 shifter, meaning that split-second
decisions have to be made between all 7 gears. With Flyzipper, there are
only 3, but each of those can be modulated through a whole spectrum of
shades when there is leisure.

But the Dualdrive is more complex, so you seem to be misunderstanding
something somewhere... With the Nexus 7 if you want to change up,
change up, if you want to change down, change down. There's no "split
second decisions" you have to make at all, so I think basically it's all
a problem in your head. The point of a DD is more finely graduated
gears and a greater overall range than a hub, but it really is more
complex because you've got two independent shifting mechanisms. If it
works for you then that's Good, but for future reference don't get hung
up on hubs on their own being more complex to use, because they're not!

I am amazed at the speed of this lil critter! He seems to be the fastest
of my bikes. Can it be that the advantage of lightness compensates for
the smaller wheels?

Lightness makes you quicker and as Dr, Moulton proved back in the 60s,
small wheels aren't nearly the problem that lots of people seem to
assume as long as you have a reasonably good surface, and "reasonably
good" certainly doesn't require a billiard table.

paranoid about getting a flat. Why are there no local sellers? Is Dahon
one of those American firms

Dahon are Far Eastern, and are the largest manufacturer of folding bikes
in the world.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

In uk.rec.cycling NC wrote:

: I guess this is one clue towards sorting Behemoth - new handlebars -
: assuming that bike is staying with you.

Sadly, I guess that this is a clue towards sorting Behemoth. That bike
is too bike. This isn't a fixable problem.

--
Arthur Clune PGP/GPG Key: http://www.clune.org/pubkey.txt
"Blogs are neither necessary nor sufficient for evil to triumph.
They're just what we call an enabling technology" - Danny O'Brien

Arthur Clune wrote:

Sadly, I guess that this is a clue towards sorting Behemoth. That bike
is too bike. This isn't a fixable problem.

Why be sad about it? The new bike suits the rider better even for jobs
where the roadster is nominally better (why anyone would prefer battery
lights to a dynohub on an urban utility bike and how anyone can find a
Nexus 7 more complex than a DualDrive are both beyond me, but if that's
how Elisa feels then that's how she feels) so get some money and space
back and sell it on.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

On Tue, 16 Nov 2004 08:49:40 +0000, Peter Clinch
wrote:

Elisa Francesca Roselli wrote:

Flyzipper has 20" wheels, weighs 12 kg, and is equipped with a fabulous
21-speed SRAM DualDrive shifter - three speeds in the front hub and
seven on the rear derailleur.

No, the 3 speed hub is at the back and the derailleur mounts onto it.

so. What is great about this system is that it cuts down on needless
complexity. Behemoth has a Nexus 7 shifter, meaning that split-second
decisions have to be made between all 7 gears. With Flyzipper, there are
only 3, but each of those can be modulated through a whole spectrum of
shades when there is leisure.

But the Dualdrive is more complex, so you seem to be misunderstanding
something somewhere... With the Nexus 7 if you want to change up,
change up, if you want to change down, change down. There's no "split
second decisions" you have to make at all, so I think basically it's all
a problem in your head. The point of a DD is more finely graduated
gears and a greater overall range than a hub, but it really is more
complex because you've got two independent shifting mechanisms. If it
works for you then that's Good, but for future reference don't get hung
up on hubs on their own being more complex to use, because they're not!


Hi, I meant to post earlier and then deleted the OP's original
message. I think she could benefit from reading Sheldon's write up on
gear shifting. It talks of maintaining a reasonably even cadence.
Something that Elisa may not be doing. So, for the OP, here is the
link:
http://www.sheldonbrown.com/gears.html

And here is the the link, that includes that article, as well as many
others. It is titled "Articles For New Cyclists", but I believe there
is info that is helpful to more than just "new" cyclists.
http://www.sheldonbrown.com/beginners/index.html


Life is Good!
Jeff