Curl... what you want to know?
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https://patents.google.com/patent/CN...assignee=dahon
Here are the patent drawings annotated in Chinese:
https://patentimages.storage.googlea...204021155U.pdf
curl fork.jpg
Last edited by tcs; 05-12-17 at 10:16 AM.
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Aha! I was right in my suspicions! This is a tremendous improvement; I've long thought that all folders should follow this sort of design. It makes no sense for the steerer to be part of the fork when the area which requires maximal stiffness is the elongated stem. This is the weakest area of the Brompton; their 'upgrade' to the M handlebar this year won't make any difference to stiffness when the majority of the flex originates at the stem/steerer interface, which in Brompton's case is prehistoric.
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Good guessing chagzuki.
Thor, I'd like to know if the main frame latch has had fundamental design changes since the mega-dodgy stem version that was recalled. Specifically, the bolts that hold the sliding latch plate, are they shoulder bolts? Or positively retained some other way?
Thor, I'd like to know if the main frame latch has had fundamental design changes since the mega-dodgy stem version that was recalled. Specifically, the bolts that hold the sliding latch plate, are they shoulder bolts? Or positively retained some other way?
#55
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Next time turn the phone 90 degrees.
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Actually, dude, adults use TABLETS and CELLPHONES to watch videos all the time. All the people I know use them,...and quite a few are in their late 60's to boot. Computers are no longer the main form of media consumption.
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Aha! I was right in my suspicions! This is a tremendous improvement; I've long thought that all folders should follow this sort of design. It makes no sense for the steerer to be part of the fork when the area which requires maximal stiffness is the elongated stem. This is the weakest area of the Brompton; their 'upgrade' to the M handlebar this year won't make any difference to stiffness when the majority of the flex originates at the stem/steerer interface, which in Brompton's case is prehistoric.
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I thought I remembered someone mentioning that Birdy uses a system of this sort but I couldn't find any pics on the net, perhaps I was getting confused with Mezzo. I'd assumed that since a Mezzo uses a regular ahead stem (or so it appears from the pics I've seen) the steerer must be conventional.
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Which is still fine by me!!!
At least @ThorUSA went through the trouble to create the video. I thank him for that.
At least @ThorUSA went through the trouble to create the video. I thank him for that.
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#63
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Is it?
mezzo.jpg
We see in this picture that the Mezzo stem is clearly clamped to the steerer above an Aheadset. I don't see any steerer clamping mechanism at the fork crown. This would indicate to me that the steerer is one with the fork crown. On the Curl, the steerer is one with the stem, and the fork crown is clamped to it.
dahon curl.jpg
mezzo.jpg
We see in this picture that the Mezzo stem is clearly clamped to the steerer above an Aheadset. I don't see any steerer clamping mechanism at the fork crown. This would indicate to me that the steerer is one with the fork crown. On the Curl, the steerer is one with the stem, and the fork crown is clamped to it.
dahon curl.jpg
Last edited by tcs; 05-13-17 at 10:13 PM.
#64
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Aha! I was right in my suspicions! This is a tremendous improvement; I've long thought that all folders should follow this sort of design. It makes no sense for the steerer to be part of the fork when the area which requires maximal stiffness is the elongated stem. This is the weakest area of the Brompton; their 'upgrade' to the M handlebar this year won't make any difference to stiffness when the majority of the flex originates at the stem/steerer interface, which in Brompton's case is prehistoric.
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I guess there's no justification for it beyond that it provides a kind of accurate tactile feedback that inspires confidence... I'm not knowledgeable enough to talk about 'power transfer'. If I'm riding casually on the Brompton it's fine but if I'm climbing a hill it feels like a bendy-bike, and for me that's not a good thing.
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Not sure how you are differentiating the mezzo fork from the curl. Yes the steerer is connected to the fork. But the fork blades are separate from the steerer and clamped in to the steerer.
Big difference?
Certainly no flex in mezzo forks.
Big difference?
Certainly no flex in mezzo forks.
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With the Curl the forks are clamped because it's a convenient way for the whole fork to clamp onto a steerer which is rigidly connected to the stem, this is paradigmatically different.
#68
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I guess there's no justification for it beyond that it provides a kind of accurate tactile feedback that inspires confidence... I'm not knowledgeable enough to talk about 'power transfer'. If I'm riding casually on the Brompton it's fine but if I'm climbing a hill it feels like a bendy-bike, and for me that's not a good thing.
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The Curl fork design might be because Dahon's R&D said it's stiffer or stronger or more secure or less expensive to manufacture or maybe takes 3.6 seconds less time to assemble. But I'm of the opinion that the Curl fork is designed the way it is mostly to minimize the folded envelope.
curled up.jpg
(I also note in this shot they've corralled the floppy cables by tucking them under a brake lever.)
curled up.jpg
(I also note in this shot they've corralled the floppy cables by tucking them under a brake lever.)
Last edited by tcs; 05-14-17 at 11:12 AM.
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But a special front bag may be very expensive, like the Brompton front bags. So I definitely prefer a luggage rack over the rear wheel. On that you can strap a large backpack of your own choice. And if you need to carry the bike on a staircase, you can carry the backpack on your back. And also if you would park the bike and proceed on foot.
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Personally, I prefer having a bag in the front:
A sorry decision from Dahon, especially considering most of its bikes also have a bag lug in the front.
- It avoid adding yet more weight on the rear wheel
- I can easily grab something out of the bag, and also keep an eye on it
A sorry decision from Dahon, especially considering most of its bikes also have a bag lug in the front.
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Personally, I prefer having a bag in the front: It avoid adding yet more weight on the rear wheel. I can easily grab something out of the bag, and also keep an eye on it. A sorry decision from Dahon, especially considering most of its bikes also have a bag lug in the front.
While on a luggage rack above the rear wheel you can strap a 120 litre backpack, or a 300 litre box, if they are not too heavy, without limiting the steering too much. 120 litre is the largest backpack you can buy. For people who have no car, or who go on holiday without a car, that option can be very important. That way a folding bike can also be used as a luggage trolley or shopping trolley for a pedestrian.
Last edited by George3; 05-15-17 at 06:15 AM.
#75
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Yup, Brompton's quick release bag in front is a MAJOR reason it's my preferred touring rig.
- best handling with weight carried on front
- doesn't preclude additional luggage on the rear rack, although front is always my 1st choice
- you can fold the Brompton with front luggage still attached
- the B will carry your luggage in shopping cart mode and I've pushed my rig like a baby stroller, incl. camping gear, for many hours/miles while sightseeing in places I wouldn't risk locking up (clicky).
- It's easy rig single shoulder straps into dual backpack straps. While touring, I often carry my T-Bag as a backpack for rough riding sections, through public transport, and ~1/4 mile in/out of the woods when hiking my entire rig to/from wild camping spots.
Unfortunately, it looks like the Curl's fold design (handlebar stem folds against front of head tube?) does preclude a protruding front mounting block... also doesn't seem like it would be able to carry/wheel your luggage like the B due to the main tube hump.
I also wonder how the Curl will ride without the suspension. When I first got my Brompton, I had a firm suspension block installed (just cuz everyone recommended it), but it was too brutal for me. Put the standard block back on and it rides as nicely as my 700x32 gravel bike - I can tip comfort toward either bike just by air pressure.
- best handling with weight carried on front
- doesn't preclude additional luggage on the rear rack, although front is always my 1st choice
- you can fold the Brompton with front luggage still attached
- the B will carry your luggage in shopping cart mode and I've pushed my rig like a baby stroller, incl. camping gear, for many hours/miles while sightseeing in places I wouldn't risk locking up (clicky).
- It's easy rig single shoulder straps into dual backpack straps. While touring, I often carry my T-Bag as a backpack for rough riding sections, through public transport, and ~1/4 mile in/out of the woods when hiking my entire rig to/from wild camping spots.
Unfortunately, it looks like the Curl's fold design (handlebar stem folds against front of head tube?) does preclude a protruding front mounting block... also doesn't seem like it would be able to carry/wheel your luggage like the B due to the main tube hump.
I also wonder how the Curl will ride without the suspension. When I first got my Brompton, I had a firm suspension block installed (just cuz everyone recommended it), but it was too brutal for me. Put the standard block back on and it rides as nicely as my 700x32 gravel bike - I can tip comfort toward either bike just by air pressure.