Now I have to take you to task here, because there are a number of inaccuracies...
Originally Posted by
pibach
The Birdy's short base and small wheels felt wobbly, nervous, and riding it needs high concentration.
I have posted a comparative geometry analysis of the Swift and the Birdy, and yes while the Birdy has a shorter wheelbase (than the Swift which has a typical roadie wheelbase) it is only marginally shorter. The Birdy's riding properties come from the entire frame geometry not *only* the wheelbase. Added to that, a wheelbase of around 1000mm is quite common to medium sized bikes. I don't know what the Mu wheelbase is, but even 1100mm does not make *that* much difference to ride quality in itself. Again, it is the whole bike geometry. You place too much emphasis on wheelbase, which, if you discount touring bikes, for the Birdy is average, not short.
Comparative Geometry - Birdy vs Swift [all dimensions in mm]:
Wheelbase: 1010 vs 1030 (longer is better?)
Effective top tube: both 550
Head angle: 71º vs 72º
Seat angle: 73º vs 72º
Trail: 63 vs 36
BB height: 290 both (depends on tyre width)
Stepover height: 535 vs 640
Chainstay length: 430 vs 410
Head tube length: 88 vs 125
rear dropout: 135 both
Originally Posted by
pibach
I like the Dahon handlepost hinge: i) it is nicely integrated and smooth. ii) opens/closes in a blink iii) relatively stable, mainly due to conical post shaping. iiii) VRO stem provides quite good lateral stiffness. Very strange that you rate the Birdy's handlepost above the Dahon's. Probably you have a different handlepost?
You must know about all the troubles the Dahon handlepost hinge gives. I have written a lot about it in the Dahon forums and here. The hinge is unreliable and there have been many reports of breakages. If kept tip-top by a knowledgable user, then the hinge is OK but for many average users it has given endless trouble. Denying it does not make it go away.
The closing mech of the Birdy is *far* more reliable and foolproof. By design it cannot self-loosen. The piece parts are much more robust. It is not for nothing that Dahon has abandoned the dodgy inside lock in favour of the outside V-channel which the Birdy has been using since the beginning.
The post is also conical like the Dahon's. Stiffness - by my experience there is no competition if you compare same length telescopic posts.
The opening/closing is just as fast as a Dahon's. Essentially exactly the same action.
Originally Posted by
pibach
b) I probably ride differently than most other folding bike owners? I come from MTB racing. I am an aggressive biker. Sometimes very fast around in town. The Birdy is not designed for this. The Mu isn't designed for it either. But it is quite similar to a BMX feel. It is surprisingly direct, agile, and fast around in town. I like this feel. Stand-n-hammer is no problem. Only I abstain from jumping stairs with the Mu (but hop front and lift back over curbs).
I regularly stand and hammer my Birdy. The front suspension does bob, but does not necessarily waste energy - it largely disributes it over a pedal cycle. But this is a separate topic. And I trust the Birdy frame a lot more than the Mu's and Dahons in general of which there are any number of cracked frame reports.
Originally Posted by
pibach
c) the Birdy's suspension didn't please me, particularly the front. It is not stiff. No real damping. It does bounce. It does pivot in the wrong direction (in contrast to other parallelogram suspensions such as the German A or Pacific Reach) giving a bad progression curve (diving effect when braking). It prohibits hands-free riding, which I do a lot on the Mu.
The front suspension is adjustable both in stiffness (different springs) and damping (different elastomers inside spring). The pivot is exactly in the right direction - up and backwards largely along the axis of the steering. The braking is 'anti-dive' - the parallelogram is stretched open when braking, countering diving. This is determined on which arm of the parallelogram the bakes are mounted. Both leading and trailing link suspensions are commonly used, there is no clear advantage of one over the other, except in the leading link the brake placement is much easier.
Free-hands riding I concede - it is not possible at all with my Birdy but others have reported that it is possible. I think handlepost geometry may be the contributing factor.
Originally Posted by
pibach
d) folding seems to be quite premature. The handlepost does not come neat towards the main tube. All together it is pretty much the same folded size as the Mu. Although the Mu is much longer (unfolded) and has bigger wheels. Folding speed is much faster with the Mu. Then you cannot wheel the Birdy. It does not stand stable when folded. Quick fold dosen't stand stable either. Rack needs to be unpacked when folding.
No no no no.
The handlepost folds precisely down left of the main tube next to the rear wheel, bar parallel to the frame. The hinge angles are designed for it to fold in exactly that way. When folded, it holds the fold together naturally - no afterthought magnet kludges are needed to prevent the bits flopping all over.
Folding speed I would call same as the Mu - it depends how practiced you are. But there isn't anything in the fold that prevents a snappy fold. There is a youtube somewhere that shows how quick a practiced action is. But it is rather silly to argue about a difference of a few seconds - what are you going to do with those seconds? Gloat at other folding bike owners?
The Birdy can be wheeled on the front wheel if it isn't folded back. Fully folded I would agree. Personally I find the wheeling argument a bit silly. If I need to wheel my bike, I do so unfolded. Much easier and no extra hassle to fold it where you finished wheeling it.
It stands stable when folded - not sure why you make this claim. Fully folded it is designed to have 3 points on which to rest.
I commute on mine daily and I have a rack top bag; the folding action of the rack means the bag does not have to be removed when folding. The bag ends up sitting neatly in a vertical orientation behind the folded package. Half or fully folded it stands stable.
I don't think the Birdy is a perfect bike but it is streets ahead of any Dahon you care to throw at it. Except for price, but I am willing to pay for that sort of quality, you pay less in the long run.