Thanks everyone for the help. As 50PlusCycling mentioned, I'm realizing that this bike was customized much more than I expected. The good news is that it's giving me a chance to get to know my bike a lot more than I expected (with the obvious assistance of the very kind people in this forum).

On a separate note, anyone know where to get a front elastomer? I think in the process of folding/unfolding my bike, mine must have come out somewhere. Unlike the rear elastomer, the front one is surprisingly hard to find online. If anyone has any leads, ideally in North America, I'd love to hear them.

Thanks again!

I bought a front elastometer yesterday for £16 from Avon Valley Cycles in Bath, UK. They have hard and soft versions. However, really they are just a bit of high density foam - easy to fashion one with a razorblade and a bit of foam I reckon. The soft version has a hole down the middle you could fashion with a heated skewer or screwdriver - the hard one for heavier riders does not.
I have a LitePro 52' replacement chainring - works fine and less messy (ie no plastic retainers) than the original. I have spare 52 and 48s.
I also got a Birdy Bargain recently - a very good condition 24 speed 2001 model for £270. They are around occasionally - usually sold by people who don't know the real value of these bikes, whcih tend to run above £500/US$700 on Ebay and such sites.
On brakes, AlixPress (Chinese exporter website working in English - reliable) - do many aftermarket spares suitable for Birdys. You can get color coded lightweight V brakes, replacement suspension, chainrings, seatposts, , brake cable microadjusters, v brake adaptors to use 20" wheels , etc. Sometimes you have to dig a little deep on their site to find all the litepro parts. My stuff was delivered to the UK in 2 weeks, postage free. I got a chainring for $15. New 18" wheels, each with 4 bearings and red in color, can't remember the price but they are good and they are still selling them.

Even cheaper from AlixPress - see my other post.

I have a Nitto rack and it does rattle a lot. Some plumber's tape around all the rattling bolts would help. That bike (I have 4) sounds like a bag of nails on the road!.

That tyre you have, the one with the central groove, is a very slow one by the way. They have not been sold for a while.

I found the 52t with 11-32 cassette too slow so I went with a Litepro 58t because its the cheapest of the big chainrings on ebay. You can see it on the previous page; post #1008 . I wish it was faster but a bigger chainring with a tall 32 rear may make the chain might rub the swingarm.

What about adding a three-speed gear hub, effectively turning that Birdy into a Sram Dual Drive while keeping a more reasonable chainring?

Thanks. I had seen Avon Valley Cycles in my initial search, but it seems they don't ship outside of the UK (I'm in Canada). But thanks for the info about construction. Any chance you have a way to measure the outside diameter and length?

Birdy Stormtrooper at Birdy Global Community

https://cimg7.ibsrv.net/gimg/bikefor...dd51c09729.jpg

Made an ID badge for my GT. The Shapeways versatile green is a bit brighter than my frame but I'm too lazy to paint it to match.
https://image.ibb.co/bXA2Sp/birdy1_painted.jpg

Nice badge indeed.

What size chain is used on the Birdy with Shimano 8 speed Alfine hubs? Being in a marine environment mine needs replacing, just need to know what to order.

Sheldon Brown says Shimano Nexus / Alfine sprockets will work with either 1/8" or 3/32" chains, so free choice. But the chainring may not because of its chainguards, so 3/32 is the safest bet I think. meaning afaik 7- 8- or 9-speed chain, or a dedicated 1-speed 3/32 chain. Kindly don't sue me if I'm wrong.
https://www.sheldonbrown.com/harris/shimano-nexus.html

1/8 would be better. If you run 3/32 the chain can become stuck between the chain ring and the chain guard. If you don't run the original chain guard, it doesn't matter. But if you do, and the chain becomes stuck (when going over a bump or something), it can be surprisingly hard to dislodge.

Good
 

I am eising virdy classic as well. It is good to ride and see.
enjoy~

It seems the single speed chain isn't a good fit for those with Alfine 8 hubs. Perfect for the sprockets, but rubs on the sides of the derailur cage. Will try a 9 speed instead.

Thanks for sharing. So the single speed chain you used is 1/8" wide, then? Single speed chains also exist in 3/32" width, which is about the same width as an 8/9-speed chain, so it should not rub anything. But I guess the difference between that and an actual 9-speed is small, and they will work equally well in practice. Perhaps the single speed 3/32" is a little stiffer side-to-side and less likely to derail.

I don't actually know. It's a Shimano Nexus single speed chain HG-X10 with 114 links. I've not really chain in the UK referred to in 1/8, 3/32 etc.. The Q&A on the website I ordered from does say it's 1/8" though.

Chains are cheap though, so no bother to try another.

Ah really not having much luck with this.

The single speed chain rubbed on the derailur cage. I bought a fancy KMC 9 speed chain, but that jumps the rear sproket in about the 10 o'clock position when under any load. Only thing left to do is to try an 8 speed chain, or give up dump the hub and get a cassette instead.

That is really odd. You've tried both wide and narrow chains now, at least one of them should have worked. Unless... could it be that the new chain is skipping because the sprocket is too worn? New chains do not like worn sprockets, and vice versa. There is an insane amount of detail on the subject here: https://www.sheldonbrown.com/chain-wear.html It should be possible to tell by locking at the sprocket and how the chain engages it.

If the sprocket is the non-bevelled (fully flat) kind, then you can simply take it off, flip it around, and put it back on again, since the back side of the teeth will not be worn. If it's bevelled, you'll probably need a new sprocket: https://lite.qwant.com/?q=alfine+nexus+sprocket&t=web

Hey Mike - what kind of contraption you have attached at the back - with the transporting wheels?
Is this something available to buy?
Cheers

I'm fascinated that the owner of this Birdy found it necessary/useful to upgrade the stock 160 mm front rotor to a 180 mm, at least that's what it looks like. 160 mm is already huge for such small wheels, when there are people who are happy with 140 mm rotors on full size roadbike wheels. And it has no racks for touring. This person has some serious stopping needs. Possibly likes to ride up mountains and race down them again. Of course you can never have too much stopping power, as long as you know how to use it safely. (No criticism from me, just... mind boggling.)

Thanks, I'm considering to get one smaller than 52t, I've found them down to 45t. I just got my Birdy with the special Sunrace 9-32t cassette (Capreo replacement). With that cassette it has more than enough high gear, so might as well get some more low gear, for loaded touring. It's fine for reasonably flat terrain, but there's no bailout for long >10% climbs. (My stock chainring is already on the outside of the spider, it would not be possible to mount it on the inside due to interference with the suspension pivot. This chainring has fat plastic chainguards on both inside and outside.)

First I have to consider alternative gearing setups, though. I was thinking 1x11 setup before, but it's clear now that this will rub on the chainstay unless I move the chainring outboard. And it's already further out than what it should be, for large cassettes. So two options remain: Either Alfine 11 (more or less enough range), or SA CS-MK3 / SRAM DualDrive setup with 9-speed 11-32 cassette (very good range). The Alfine setup is simpler, keeps the chain tensioner higher off the ground, and may allow a tighter fold, if the tensioner sticks out less than a derailer. By the way, they put a regular XT derailer on it, not the Shadow version, which might also have allowed a tighter fold. But maybe the shifter cable path on the Shadow isn't ideal given the cable routing inside the Birdy swingarm.

New Birdy Touring
 

So I'm officially a Birdy owner now. Got my green Touring delivered in the weekend. I may have to get a Kermit sticker for it, since I've already called my other green bike Yoda.

https://farm2.staticflickr.com/1911/...7eb02eb4_b.jpg
R&M Birdy Touring by gunnsteinlye, on Flickr

Extras are front & rear racks, and dynamo lighting system. Sport stem and Ergon grips. For now I'm just tuning the ride position and testing out the gearing range, to see what parts need to be replaced. I'll probably replace the Marathon Racer tyres (40-355) with regular Marathon (44-355) for better puncture protection and a bit more volume. The dealer isn't used to these bikes, he had put the seatpost on backwards and the bars at a crazy angle, but once that was corrected the ride position was quite ok, if a little stretched still. I'll probably get bars with a bit more backsweep, which wouldn't work at all with the other stem. The ride is lively, my other bikes have more relaxed steering. At my weight the standard elastomers move quite a bit and give comfortable damping, just as I like it. The fold has one more step than the Tern I used to have, and is a little confusing at first, but is more compact I think and should work well once I'm used to it.

A little worrying is that neither wheel was completely settled into the dropouts, but a bit angled. I'd expect R&M to ship it folded with the wheels on, if so it was mounted wrong at the factory. Otherwise it's the dealers fault. Either of them should know better.

Gearing: It's got the regular 52t chainring. Rear it's got an XT derailer, and a special Sunrace hub & cassette combination that isn't compatible with anything else. The cassette is a 9-32t and 10-speed, and is used instead of Shimano's discontinued Capreo system. It shifts well enough, seems accurately adjusted. The tiny 9t cog means you get lots of high end gearing with a normal chainring, despite the small wheels. The 356% range goes from 2,1 to 7,4 gain ratio, a bit low range and high gearing for a touring bike, I'd say. Something like a 42t chainring would make more sense if touring someplace not flat. A dualdrive setup would give all the high and low end I could wish for. An Alfine 11 with 409% range might also be enough. I wish they'd sold it like that. The Nexus 8 they do offer just isn't enough, with it's 306% range.