The suspension of the Birdy and Moulton have a short stroke of only 25mm and cannot be compared with mountain bike suspensions that have a much bigger stroke.

The loss is minimal and on rough road you actually ride faster with a suspended bike than with a not suspended bike. And if you want even more confort, with the 18" wheels you can mount 50mm wide Big Apple tires.

The gearing of the Pacific Cycles Birdy with 52/11 and 18" wheels (or even 20"wheels) is much too short.

Riese und Müller Birdy with derailleur use a special 9-32 cassette (and special rear freewheel) that provides a much longer 52/9 ratio (about 7.8m depending of the tires size).

I changed the wheels to have a SRAM XDR freewheel and mounted a 11s 3T 9-32 cassette.

I agree that on very rough pavement, shocks make the bike faster. And while you find the loss minimal, I found it constant. Over the years I had two Moultons and eventually parted with them. I have not had a Birdy. My small wheel bike is my Brompton, which has a shock and needs the shock for comfort.

My experience is that the rear suspension both of the Moulton Speed (note that the Moulton AM and older models have a different rear suspension) and Birdy do not cause an efficiency loss.

The main benefit of suspension for speed on rough road comes from the front suspension that makes the bike safer while the rear mainly affect the comfort.

I have also a Brompton, a superlight with titanium fork and rear triangle, on cobbles the front wheel bumps from one cobble to the next and force the rider to reduce its speed.

The problem of the Brompton is the combination of small wheels + rigid fork + narrow high pressure tires.

I am afraid that the same will happen with the very rigid single arm fork of the Helix.

The bigger wheels won't help a lot because the tires are too narrow and too high pressure. Peter should have made the frame to accept 50mm wide tires (which is the most common width of ETRTO 507 tires).

I have a titanium frame with carbon fork road bike with even bigger = ETRTO 622 high end wheels and even with 28mm wide tires, the same happens.

The only clear benefit of bigger wheels is on soft ground, sand for instance, where the smaller wheels are blocked faster. But also in this case, wider tires are needed.

I find that that the primary suspension and the best are the bike's tires. I too have a 622 with nice lare tires, 38. On the brompton I run Primo Comets at 65 to 75 psi and it helps. I like wide supple tires and may try Scorchers next. I find rear suspension is to be more beneficial than front. It is the comfort that is letting you ride faster on broken pavement.

we would be interested in two helix bikes with 10 speed derailleurs...

dear bike forums

thank you for your pm. i cannot replay because i have not 10 posts yet ;o)

we're based in switzerland. what is the fs section on bike forums?

best, namor

For Sale is fs. You should be able to find it easily. Roger

The Primo Comet are indeed very supple tires and even if they aren't really wide, they provide some comfort.

For the Greenspeed Scorcher, they are currently 40mm wide and as far as I know too wide for the Brompton (I saw there was s narrower test version made for the Brompton but not in production yet I think).

Now, a full suspension Birdy even with narrow high pressure tires like the 32x355 Kojak at 8bar provides a level of safety and comfort on cobbles totally unknown with a Brompton, whatever the tires used.

I agree, over cobbles a Birdy or a Moulton are going to be more comfortable and faster. Its all the other time that you don't need the weight and lower efficiency of the shocks, that led me away from them.

If you can fit the Scorcher on the Brompton, they will surely be a very good solution, they are wide, supple, fast tires. Maybe without mudguards ?

But Greenspeed made a narrower test version of the Scorcher especially for the Brompton, so the 40mm won't fit on all Brompton's

In New Orleans, mudguards are a must. There is this to go by but I don't think I will need to go through all that just looking at the bikes. We shall see after I accumulate more wear on the Comets.

So, its the rear fenders and its mounting that cause the problem !

With the original rear fender, there is indeed not enough clearance between the tire and the fender, sooner or later dirt will clog between the tire and the fender.

Removing the mudflap of the rear fender is a very bad idea, it is this mudflap that mostly protect the rider.

thanks. found it. a little too steep, though...

Front will no problems. The rear may as well. I see no problem with the mud flap or at the front. The tire will be 1/8-inch taller and 1/16-inch wider at each side. I could possible raise the rear flap an 1/8-inch if I had too.

It may not work out in practice. The next time I need a tire I will buy one and try and post. Right now I don't need one. If it does not work in rear I can use it in the front where cushion is needed more.https://cimg0.ibsrv.net/gimg/bikefor...69cc73e517.jpg

So true

What was the final verdict on the seat post?

I'm looking at the helux tube here at house and it looks round to me

So how is Helix doing? Should be around 200 bikes shipped by now?

Helux seatpost
 

Helix not too bad. I'm replacing saddle to something more comfortable to me. But other then that not too shabby.

Helux seatpost
 

Helix not too bad. I'm replacing saddle to something more comfortable to me. But other then that not too shabby.

I checked the website.

Is it possible to order one now?

I do not think so. They have a lot of paid customers still waiting for bikes. Roger

Helix
 

My understanding is that they will be selling to the general public. The supporters will eventually get a bike but down the road

I just received an email offering December 2019 delivery. Prices are $3500-4k. Contents here for those who did not receive it:

$3500-4000. Somebody in this thread predicted this years ago...