Well, there you go...
 

A second person telling you straight up long-cage is a no-go on 355. Long-cage only begins to have sufficient ground clearance on 451.

It's a risk, yes, which I must weigh against the risks/flaws of other approaches. I'm not at all decided yet.

I'm talking about the new 2019 models. The Touring is pictured with the BB chain tensioner. The City with IHG isn't, but that could of course just be an old/wrong picture.
If I go for a Dualdrive or Sturmey Archer CS-RK3, I could use a short cage derailer with a 9/10 speed cassette. I'd have to check for suspension movement chain growth/shrink first. Worst case, a medium would work.

I would use the Marathon 44-355. Better puncture protection and a bit more clearance.
(I'm using 55-406 Big Apple on wide BMX rims, on another bike with medium cage derailer and front triple. It's close, but not too close.)

I've only test ridden a Birdy for 5 minutes, never tried the fold. Could you please share what you think the flaws are?
AFAIK it's the ONLY high quality full suspension bike out there that folds quickly, conveniently and compactly. That makes it easier to forgive some flaws...

I hear you. Yet I also hear Riese & Müller, the people who designed and developed the bike, say the long cage is fine (implicitly, or they wouldn't have sold it like that). So I'm not decided yet. Whichever way I go, I'd have to build a new rear wheel. Which means I should buy the Touring with the long cage, just because it's slightly cheaper than the City model. There are hardly any differences apart from the rear hub/gearing and tyres.

Here we have a Kojak tyre, which in 355 size only exists in 32 mm width. A 44 or 50 mm tyre adds height. Second, this is offroad: dirt, leaves, plants. Riding paved only and being careful means you get much less crud like this. Again, I don't believe R & M would sell it with a long derailer if it was a terrible idea. It clearly does work well enough to pass quality control of a quality conscious German company. Yes, it does mean increased risk of failure, and a need to take more care when parking offroad, and increased chain wear due to more sand and dust being caught by the chain. Disadvantages which must be weighed against disadvantages of other solutions. NB: I appreciate your input and I agree on the risk, I just don't see it as quite as unworkable as you seem to do.

The 9-46t cassette with long derailer is tempting due to the simplicity of such a solution, but it's a pretty high price for a consumable part, and may not clear the chainstay. The SA CS-RK3 IHG with 11-34t cassette and short derailer solves the clearance issue and gives enough range, but is more complex, and the angles of the Birdy means rain will follow the indexer cable into the hub. These are the only two options with acceptable range and cost I see at the moment. I won't decide until I have the bike in front of me and can do accurate measurement.

Thanks! I'll give them a try.

https://cimg2.ibsrv.net/gimg/bikefor...f014ba1257.jpg

if you check my red birdie I have a large cog r mech which sloves some clearence issues
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Hi again. Could you expand on this please? In what way does it affect the fold?

You can run a medium cage derailleur for up to 34 teeth, a long cage is not necessary. I've run a long cage with 355's, but it often hits things like the lips on curb cuts. I converted my Birdy to 406's, with the medium cage derailleur, and clearance is no longer an issue.

Hi again. Could you expand on this please? In what way does it affect the fold?

You an run a double on the front of a Birdy without interfering with the fold, but you have to make sure that your crankset has enough Q factor, leaving enough room for the front derailleur to travel. I used to run a double on mine with no troubles, but after converting to 11 speeds, two rings on front was no longer so necessary, so I went back to a single.

Yes, one of my options is Dualdrive or SA CS-MK3 with 9-speed cassette and short or medium cage derailer.
How big tires do you think one could fit with 406 and mudguards? All the 406's I have seen have been using narrow racing tires which are a no-go with me. If 40-44mm won't fit, then I'll stay on 355.

What sort of 11-speed is that, cassette or Alfine? What cassette size? I'm curious about whether big-range cassettes will work without the chain rubbing the chainstay. Thanks!

i wondered the same thing, so i posed the question directly to PC. Their response, posted on the MTBR Folding and Travel bikes channel is that no, it cannot take tires as wide as that.

I'm currently running an XTR cassette on an Ultegra 6700 hub. I've run an XT 34t cassette on an Alfine hub on my previous Birdy. I've never had a problem with chain rub.

Nice! Do you know what size the biggest cog is - 36t, 40t, larger? The 11-speed XTR goes at least to 40, possibly larger.

The 11 speed is 11 to 40 teeth, it looks like a dinner plate on 20" wheels. I've looked at the 12 speed, but don't need anywhere near that much gearing, and I would have to change my hubs. On the other hand, it would look pretty cool (which is important). Tempting...

Excellent, thanks! That gives decent odds that the SRAM 10-42t and the e*thirteen 9-46t cassettes will work, perhaps even the SRAM 10-50t. The Shimano 10-51t is still more expensive than the others and requires a dedicated hub, while the former three all fit the same XD driver, so I'm leaning towards that standard.

Good evening. Some of you may recall me posting a few questions about an older Birdy for sale near me. I appreciate greatly the advice I received, and ended-up purchasing it for a very reasonable $300. The gearing, as purchased (with cassette removed) was much too low. So my first order of business was to get a cassette back on it. However, I noticed that in the lower 4 gears, the chain rubs against the frame (see the photos below; sorry they're a little crappy). The last photo is of the chain in the highest gear, with the resulting clearance. Am I missing something obvious? The bike was obviously made for an 8-speed cassette, so I'm wondering what I'm doing wrong.



https://cimg4.ibsrv.net/gimg/bikefor...9b9cebdb48.jpg
https://cimg3.ibsrv.net/gimg/bikefor...4cfd85c64f.jpg
https://cimg6.ibsrv.net/gimg/bikefor...04f8049f3c.jpg
https://cimg5.ibsrv.net/gimg/bikefor...a55fea3fda.jpg

Also, I'm wondering if I'm folding it correctly. When folded, should the 2 wheels be parallel to each other? I can't seem to get it that way since the side of the front wheel hub hits the rear derailleur. Maybe that's normal, but I'd love it if someone with more experience could confirm.


https://cimg5.ibsrv.net/gimg/bikefor...2b63566c46.jpg

https://cimg6.ibsrv.net/gimg/bikefor...b68849216c.jpg

Thanks very much!

That's insanely cheap!!! :eek:

Unlike a Brompton the wheels do not end up parallel. I seem to recall that the front wheel should tuck in a bit more, which would let the handlebars tuck in better too. A current owner should confirm...

The current Birdies are sold with a 52t chainring. Your chainring looks a bit smaller, and your chain seems to miss the cutout in the chainstay, just above it. If the chainring isn't original, the whole crankset may not be either, in which case the chainring may also be too close to the center of the bike. But judging from how big the chainring protector is, it looks like it's just the chainring that has been swapped out for a smaller one.

Looking for a decent lightweight rack for my Birdy MK2 frame. Anyone know of a supplier in the EU?

Also, I just don't get on the original v-brakes. What are my options in terms of replacements?
https://cimg9.ibsrv.net/gimg/bikefor...a485305cf7.jpg

If you mean getting rid of v-brakes alltogether, then I'd consider Sturmey Archer drum brakes, at least on the front. They're weatherproof and would give very good braking performance on such small wheels. (It would be an expensive swap for the rear, which looks like a Nexus IHG.) I avoid rim brakes on my bikes, but that's a matter of opinion.

Nice photo!

Thanks very much for this info. You're definitely correct about the chainring... the one installed on my bike is a 48t. And until you mentioned it, I hadn't noticed the cutout on the chainstay; such a small yet obvious detail. However, the cutout is still about an inch above where the chain is currently. Will a 52t chainring make that much of a difference? Would you also happen to have any info about the original crankset, in case I need to go back to it? The Birdy is such an elusive beast around here that I'm not sure that many bike shops will have experience working on them. I feel that if I can provide as much info as possible, that will make the job of making sure everything works that much easier.

Sorry, I don't have my own Birdy yet, I don't know much about it. You're right that 48 to 52 teeth won't make much of a difference. NB: The current model I'm referring to has a 52t chainring combined with a special 9-32t Sunrace cassette. They used Shimano Capreo cassettes before, also with a 9t smallest cog. Those require special hubs. If the cassette you got for it is a common cassette with smallest cog of 11t, and that fits the hub, then it would require a bigger chainring to get normal gearing. Perhaps something like 58 or 60t. And that would lift the chain high enough to reach the cutout, it seems. So it could be your model was made for a big chainwheel like that. But this is speculation on my part.

It looks like your bike has been modified a bit. The front chain ring is not right, it looks like a double, with the chain on the small ring, and a chain guard bolted on to where the outer chain ring should be, this is the cause of your chain rubbing. This setup might work on a another bike, but not a Birdy. You can check the crank set bolt circle size, and buy a 52 tooth chain ring, and put it on in place of the chain guard, that will get the chain away from the swing arm.

You can run any Shimano square taper crank set, you can also adapt the Octalink or Hollowtech crank sets and bottom brackets. The stock crank set is quite heavy, it was the first thing I swapped out on my Birdy. I like the Hollowtech 2 crank and bottom bracket (Ultegra or Dura Ace), which weighs half as much, and is not hard to find.

The fold is correct, the front wheel will stick out a little. You can get the fold tighter if you use a more compact derailleur. You can run just about any Shimano cassette and derailleur, from 8 speeds to 11 speeds.

The stock V brakes on Birdies suck, they are mushy, and they rattle and make noise. Any higher-end V Brake will work, and be quieter. I run Shimano XTR V brakes, which still rattle a bit, but have much better modulation. I use a folding titanium carrier on my Birdy, when the bike is folded, the wheels on the carrier tuck underneath like a Brompton, allowing it to be wheeled around. You can even stand a Birdy up vertically on this rack. I got it at Yahoo auctions Japan, but it was sourced from a distributor in Taiwan. It's strong, weighs almost nothing, and is quite tough. As a plus, the wheels don't rattle like the Nitto rack. Ttianium Birdy Rack

chain clearence frame clearence, chain line
 

I run a litepro combination chainguard and cog set. Its around 25£ on ebay. Then you can mounted the combination with the cog on the outside of the crank spider. This solves many issues. Like frame rub. Tyre rub.
clearence of cogs from rear frame stays on folding.