RandomHajile

dirtjump and slopestyle Are BMX ???

even the action pictures schwalbe use don’t look like they’ve used a BMX


the suspension forks and big 26inch wheels make me think this is a jump bike not a bmx

Jipe

The picture show clearly that its not for road or trail use.

Therefore probably not really puncture proof.

But, anybody can try it and on some places roads are clean without debris and a sophisticated puncture protection isn't needed.

Geepig

I have been riding off-road since the 1970s, and back then with a standard bike on 26x1.25" wheels the choice was road tires or slightly racier road tires. I had the occasional puncture, but that usually occurred if you rode your tires into the ground or in the vicinity of Blackthorn trees, for example. These days I live in another, sandier country that also has Blackthorns and I would quite happily use something like billy bonkers for summer road and trail riding. In the snow they look like they will clog easily, and if I still lived on clay then they would not be much good anytime it was wet.

The choice really depends on where, when and how you ride.

Estuche

Hi, does anyone here have experience with the Kamoya suspension? It seems like it would greatly improve lateral stability?

Jipe

Why should it improve something that isn't a problem ?

The fork is stiff enough by itself, no lateral stability problem.

What seems sure is that it will increase the weight.

As for the Brompton, there are many useless, if not not working well third party custom components for the Birdy sold at an outrageously high price.

The basic concept of this front suspension is questionable: if the two springs do not have exactly the same stiffness, they will tend to create a distortion of this suspension.

Estuche

So Jipe am I reading this right? Are you suggesting that this kamoya product is "useless" and "outrageously priced," and if so is this based on actual, real life experience with the product, or speculation? I think Kamoya (Kuosac too) often innovate, and their approach is worth some consideration and thought. Kamoya was likely one of the first to come up with a radically different design on Brompton's rear suspension, which was then grossly copied by others. Perhaps having to spend over US$250 on a multiS G5 front suspension would produce more outrage in at least some folks than this $95 one would if it works fine, as ugly and heavy as it may be

To continue a friendly argumentation I found some videos. Note that Kamoya has a "silky" version aimed at absorbing as much chatter as possible, and a stiff "super" version.
Youtube vids here:

And here:

Short reviews here:
https://translate.google.com/transla...241/parts.aspx

And here:
https://translate.google.com/transla...g.jp/10310161/

Jipe

There are two things.

First the supposed "greatly improved lateral stability".

How would this suspension do that ?

Because this dual spring is wider than a single suspension ? That's pure b...ls..t because the frame side is connected to the frame in one point with only a hook.

Second, what's the difference with the original spring+PU+foam ?

Both are spring based, the Kamoya seems to have only springs in compression (the PU is in rebound, note that the two video and the picture show slightly different suspensions) while the original has spring+PU+foam in compression, so not better (the Multi-S has a real damping).

And this Kamoya has the same problem as most other third party front suspensions for the Birdy: the spring is shorter than the original one what makes it less progressive.

What I see in the video is... what I see when riding my Birdy with its original suspension, a spring that absorbs the road roughness, no evidence that it does it better.

Note that there are two springs for the original front suspension, 8.5 turn hard and 10.5 turn normal stiffness and two foam stiffness.

The reviews both show an old Birdy model, not the current one (BTW. I saw the same concept of front suspension mounted on a Frog, the now discontinued old little brother of the Birdy).

Last point, with two springs, two big rods inside the springs, two assembling thick aluminum bars, this suspension (like the Kamoya suspension for the Brompton) must be very heavy, much heavier than the original one.

I spent enough money in third party components for Brompton and Birdy that appear worse than the original one and some of them so badly designed that you wonder if the seller/designer ever tried to mount its component on a Brompton or on a Birdy !?

Jipe

There are two things.

First the supposed "greatly improved lateral stability".

How would this suspension do that ?

Because this dual spring is wider than a single suspension ? That's pure b...ls..t because the frame side is connected to the frame in one point with only a hook.

Second, what's the difference with the original spring+PU+foam ?

Both are spring based, the Kamoya seems to have only springs in compression (the PU is in rebound, note that the two video and the picture show slightly different suspensions) while the original has spring+PU+foam in compression, so not better (the Multi-S has a real damping).

And this Kamoya has the same problem as most other third party front suspensions for the Birdy: the spring is shorter than the original one what makes it less progressive.

What I see in the video is... what I see when riding my Birdy with its original suspension, a spring that absorbs the road roughness, no evidence that it does it better.

Note that there are two springs for the original front suspension, 8.5 turn hard and 10.5 turn normal stiffness and two foam stiffness.

The reviews both show an old Birdy model, not the current one (BTW. I saw the same concept of front suspension mounted on a Frog, the now discontinued old little brother of the Birdy).

Last point, with two springs, two big rods inside the springs, two assembling thick aluminum bars, this suspension (like the Kamoya suspension for the Brompton) must be very heavy, much heavier than the original one.

I spent enough money in third party components for Brompton and Birdy that appear worse than the original one and some of them so badly designed that you wonder if the seller/designer ever tried to mount its component on a Brompton or on a Birdy !?

2_i 

I have a Kamoya kickstand for Brompton. It is an overthought, overengineered product that is useless in practice. I also have the said Kamoya suspension for Brompton. It works reasonably, but then its design route went close to that of Brompton, nothing radical there, just an incremental improvement.

Geepig

Look at the side view, and then look at the spring unit. Notice how much less substantial the spring part is. As an engineer formerly with a motorcycle I would only ride a bike with that suspension up and down the yard. I can see that it is underdamped, and there is a good chance that on a fast down hill bend any obstacle will skip your front wheel from under you. There is a lot more to suspension than stiffness, and I cannot see anything to keep you and your machine together unless you stay on good paving in good weather.
You could try this out on the BMX forum, as they have experience there with small wheels and suspension.

grayrest

Well, Multi-S used to make a $70 shock that they discontinued when they intrroduced the $200+ version. The new one has some adjustability but the old one works fine for me and I'm disappointed they no longer sell it.

Estuche

Good discussions so far! A few things: Any suspension system will have limitations, including under which conditions it will perform well or poorly. A key, obvious thing to think about as a buyer is what conditions one is using a given bike under, and which "assets" one personally values the most. It may be price, weight, adjustability, lack of maintenance, looks, part availability, etc. Many suspensions with "active" damping will require servicing; this is less of an issue with parts that any LBS has available, and a headache for a niche bike owner. Again, experiences may vary, real life experiences that is!

Another important aspect is that of the rider as a damping "agent"; in addition to any suspension choosen, do play with tire pressure, and know when to accelerate and when to stop, really basic stuff. The 355 wheel size doesn't get as much love as it deserves IMO. It is nice to have winter studded tires, true offroad tires, marathons for commuting, and the lightest slicks still in production (e.g., Minits, 150gr per tire) all in one place.

On a related note, just FYI, the recently released Bonkers tires look cool but are a level 2 tire, so no good protection, per Schwalbe.

Estuche

The physicists and engineers may chime in, but I do wonder if the fact that the two springs, being situated between the front tire, rather than it being a single rod in line with the tire, can have a meaningful effect. For example, the regular (and most of the aftermarket) Birdy spring will likely work great for hits that take place near the center of the wheel's trajectory. What happens however with off-center hits? Or are suspensions like the MultiS as stiff as, say, Cannondale's Lefty? Because that would be pure b...ls..t

Is having a spring a bit closer to an area of impact completely unimportant? Or two springs to carry and balance out the load of offset impacts? Perhaps it's negligible! Ideally some tests are performed at some point of the various options out there.

Jipe

The front suspension unit (spring based are anything else) lower end of the Birdy is bolted to the moving part of the fork.

But the upper end isn't bolted, its only slightly nested in the fixed part of the fork and held by a single hook.

There is no rigid link between the suspension unit and the fixed/suspended part of the fork that could provide any rigidity improvement of the fork.

The lateral rigidity of the fork comes from the two axles between the moving part and fixed part of the fork located at the bottom right and left side of the fork. Because the fork is quite wide at this place, it provides and excellent lateral rigidity.

Another problem with third party Birdy front suspension unit is that the hook has a curved shape meant to fit to a spring. It isn't adapted for the square shaped groove of third party front suspension. As consequence, the front suspension is not firmly held by the hook, there is some play that you feel when there are rebounds.

timo888 

I'd agree that there is no lateral instability issue to begin with. BTW, that first video when played at 0.25 speed is like a bad LSD trip. (Lateral Stability Device)

alfabob

Hi all.


New joiner here. I've owned a Birdy New Classic Gen 2 since 2 years ago. However, its not had as much use as my Tern Link. This is mainly due to the short stem and lack of racks and such in Malaysia.

Anyway, I've finally found an expedition rack for the Birdy that can fit the Gen 2. I was wondering if anyone here can share a photo of their Birdy with a similar rack in the folded position? Trying to see how whether the I can still use my EZwheels to wheel around the Birdy with the Expedition Rack.


Also, has anyone been able to adapt something like a Tern Luggage Trust to the Gen 2 New Classic?

Jipe

Couldn't find a picture of a Birdy with the expedition rack.

But the titanium rack is exactly the same, below a Birdy with titanium rack. Yes, you can wheel around pulling the bike from the front (the best is pulling it with the low ride rack that become a handle when the bike is folded).








You can mount a Brompton front block adapter to the Birdy: https://bikegang.ecwid.com/#!/Brompt...tegory=9988082

JRat

I'm another new Birdy owner who has read through much of the valuable discussion in this thread. I bought the Birdy City (European model with Nexus 8 gears) in the hope that I can add a second, smaller, chainring to extend the gearing range. I see from this long thread that has been done. So far I've figured out (i) the chainguards have to be sacrificed and (ii) the smaller chainring (38T is the smallest available in 130BCD) is fitted on the inside of the cranks. I've found a source of front derailleur clamps which claim to fit the 40mm dia seat tube but I'm having trouble in identifying a suitable front derailleur mechanism. Any suggestions? The Birdy pictured above appears to rely on manual shifting between the chain rings.

Jipe

Ridea and Color+ have specific front derailleur clamp for the Birdy.

You need a classic down pull front derailleur like for instance a Shimano 105.

To have the chainrings at the standard distance from the frame, you need a compact or double road crankset with the biggest chainring mounted on the external side of the crankset and the small chainring mounted on the internal side of the crankset (like you can see on the pictures of the Birdy with H&H rear rack posted above, the crankset mounted is a Shimano 105 double road).

The clamp has a plate to mount the derailleur like on a frame with a front derailleur mounting brazed on and a hole on the rear to receive the front derailleur cable housing. This cable+housing must come front the bottom.

Look at this link to see how to mount it (its on a Dahon but its the same on the Birdy).

Last point, you must pass the cable+housing inside of the Birdy frame through the foreseen holes like its done for the rear derailleur and rear brake cables+housing. The cable+housing of the front derailleur must do a loop like the cable+housing of the rear brake on the left side of the bike and go up to the front derailleur mounting clamp.

JRat

Thank you for the advice and suggestions. However, as I'm in UK I've decided to first try what is available here so I've ordered a 2-piece front clamp unit (item B07T4KTZBD from Amazon UK) as it's both cheaper and quicker to get than something from Asia. If it becomes obvious that it won't work then I'll have to move to a more expensive solution. The photos with that product listing also illustrate your point about the cable routing from below - I had been thinking of the cable pulling from above which would be a straighter routing from the hole in the frame.

I don't want to be changing the crankset if I can avoid it. The current chainring on the outside of the spider is about 48mm from the centre which is not a very good chainline for the hub gear which is 42mm. Initially I am planning to try a 52T (ie existing chainring) / 38T chainring combination but, if successful, would like to substitute 54T to give slightly higher gearing when on the big chainring.

2_i 

Most likely you will not be able to prevent the mounting finger from rotating in that adapter. Even if you initially have some success, the tab that acts against rotation will soon shear off. Maybe the design could have worked if these units were made to a higher precision, but they are not.

Jipe

Most bikes factory equipped with a front derailleur use a cable+housing coming from the bottom and most front derailleur (I could even say almost all) are made for a cable+housing coming from the bottom.

My Birdy was factory equipped with a front derailleur and a 52-36 compact crankset and has its hole in the frame above the derailleur. Nevertheless, the cable+housing make a loop to the bottom so that they can come into the derailleur from the bottom.

I listed Ridea and Color+ which are high end expensive brands as examples but there are cheaper types from Litepro for instance available on Aliexpress.

JRat

That clamp has already arrived and I see your point about the anti-rotation tab being flimsy but it's probably only there to keep things in alignment while the bolt is tightened. My current objective is to confirm that I can get the front derailleur to work. I can then get a better clamp.

Thanks.

I've been occupied by the search for the other components. The Shimano FD-5700 appears to be the only front derailleur which is designed to acommodate a maximum chainring size of 56T (it's rated at 56T although I'm planning 54T - other derailleurs are designed for 53T or smaller) and my proposed shifter is a Shimano RS31 Revo twist shifter (old design but new stock) which isn't indexed and thus avoids the issue of compatibility with the FD-5700.

JRat

I've now tried that braze-on clamp from Amazon UK (B07T4KTZBD) and agree that it won't work. The problem is that the part holding the rear clamp fixing bolt conflicts with the rear triangle. This prevents the clamp from being placed low enough for the braze-on mount to be at the right level (when I tried the clamp on the bike the braze-on mount is 7cm above the top of the chainring, which looks to be too high). I've now placed an order with Bikegang. I note that the specific Birdy braze-on clamps have the clamp tightening screw placed where it doesn't conflict with the rear triangle. I'll send part B07T4KTZBD back to Amazon.

Samidare

I wouldnt suggest getting the brompton front block on a birdy though.
If you own one i suggest that you get it removed.
Reason being that if the front blocks moves it will cause the front suspension clip to be loose and will likely cause an accident.
With regards to the rear rack. Any reason why an easy wheel which is lighter cant be use ?