I understand it’s a local website which I can’t even read. Maybe it costs this much locally in Indonesia which is of little help for me. Thanks for sharing though.

Just wanted you to know how much things cost here closer to the manufacturer and how much you are getting price gouged over there in Europe. The part will, of course, be even cheaper in the PRC.

Riese & Müller mount a Shimano RD-T610-SGS derailleur on the Birdy which is OK because 36t is about the maximum possible on the Birdy 3.

The stopper for the rear arm folding is circled in red in the picture below which also show the position of a Shimano Ultegra RD-R8000-GS derailleur on the Birdy with 50x355 tires in its worst case position (the cage is the closest to the ground on the cogs in the middle of the cassette, its higher on the biggest and smallest cogs, on your picture, the derailleur cage isn't in its worst case = closest to the ground position).

https://cimg2.ibsrv.net/gimg/bikefor...dc785398cb.jpg

About the gearing, if you are satisfied with 52x11 as longest which is about 6.7m, you could as well use a 9-34 cassette with a 42t chainring that also gives about 6.7m as longest and gives about 1.7m on the biggest 34t sprocket what is the same as what you will have with the inner small 39t chainring of your double and a 32t cog.

XDR hubs and cassettes were/are not available locally and I can’t order them online due to the high costs. I don’t want to install things which are not readily available locally and have no warranty even though the price. And no replacements available locally if I’ll need to replace cassette or change it for any other confirmation. Shimano cassettes are always available in any configuration and cheap price. Same goes for my Brompton, all parts are always available locally.

So going the way you suggested with XDR hub/cassette is not feasible for me in my location.

But you seem to buy many things on Aliexpress which is also not local availability, can't you buy those XDR parts in Asia like you do for parts coming from Aliexpress ?

Is SRAM not available in Turkey?

The problem with the current range of Shimano groupsets its that they have now several groupsets completely incompatible with each others: 12s MTB is totally incompatible with 12s road, 10s and 11s MTB for ebike (Linkglide) are totally incompatible with previous 10s and 11s MTB and with current 12s MTB and they now have new 11s and 12s Di2 MTB that only work with Shimano new Steps ebike motor !
They have also now 3 types of freewheels on their rear hubs, the old one, one for MTB 12s only, one for road 12s only.
For road, there is now in 12s only Di2 groupset but customers are waiting since many years for a MTB 12s Di2 solution, the newly announced 12s MTB Di2 isn't a solution, it works only in combination with 2 new Steps motor (previous EP8 motor isn't even upgradable to work with those groupsets).

I previously liked a lot the excellent Shimano groupset but the latest one are a mess !

I don’t buy drivetrain components from China if it’s possible. Only components that will not require maintenance or replacement.

Rear hub, cassette, chain are all bought locally, Shimano. Front derailleur will also be Shimano. Also locally. The only drivetrain thing I’ve ordered from China is double chainrings. $33.91 shipping and import tax included. And they will be available to order forever. And for this price I have absolutely no issues ordering them from China.

Jipe I get it now. You just don’t like Shimano. I’m sure you have your reasons. Here in Istanbul they have very good customer service, very, very wide service network, products availability, good prices and Shimano service center mechanics (mine is too) know what they are doing. So I see no reason why to look for alternatives.

I didn’t come across any official SRAM service centers or found they parts widely available. Only few things here and there probably imported by individual companies. I’m pretty sure they are not present here officially.

I liked a lot previous Shimano drivetrains that work perfectly well and are very reliable but not the current ones like Di2 only road 12s which are incompatible with MTB 12s mechanical only which require the special microspline hub, Linkglide fully incompatible with Hyperglyde and Hyperglide+, new MTB Di2 that work only with a Steps motor...
And all these new drivetrains have a very limited choice of cassettes that aren't good for small wheels bikes.

I don't know about availability where you are, but where I am one can get Shimano stuff from 7 to 12 speeds. I am still at 10-speeds and will stay there unless 10-speed parts are no longer available (which I reckon will be in a decade) and I am forced upwards. In other words, no one has to chose 12- or even 11-speeds or the latest that Shimano puts out. Heck, I've been thought of going back to 9-speed and would do so were it not for the unavailability of GS MTB RDs for small wheels. I mean, we've got 10-speed Zee with 11-36t for 305 and 349, we've got 10-speed Deore RD-M6000-GS with 11-42t and we've got 11-speed SLX RD-M7000-GS, XT RD-M8000-GS, XTR RD-M9000-GS and GRX with 11-46t for 406 and 451. That other mess that you brought up need not concern us at all. 12-speed? I reckon I'll get there in 2030 perhaps. No need to throw the baby out with the bath water.

The problem is that a cassette that starts with a smallest cog of 11t is not good for small wheel bikes, the gear inch it gives with a usual 52 or 53t chainring and 52/53x11 is too short and the big cogs above 42 are completely useless. Using very big 60t or more chainring is not a good solution because they aren't standard and do not fit on many folding bikes.

This is the reason why bike manufacturers like Moulton, Riese & Müller and others use special cassettes with a smallest cog of 10t or 9t.

Shimano has only one solution that accept a 10t cog, its the latest MTB 12s Hyperglide+ which is only compatible with Shimano microspline hub and only in 10-45 or 10-51 (or even bigger from third party).

Shimano had the Capreo drivetrain specially made for small wheels bike but its obsolete (cassette is max 9-28) and anyway discontinued from Shimano and n spare parts available anymore.

Therefore the choice of SRAM XD or XDR rear hub that accepts cassettes starting with a 9t cog, for which there are several cassettes options that fits very well for small wheel bikes with a wide enough gear inch range to avoid the need of a double chainring and that in 11s are compatible with SRAM, Shimano and even Campagnolo derailleurs.

The picture I put of my Birdy show such a solution : XDR rear hub, 11s 9-34t 378% range cassette and Ultegra RD-R8000-GS medium cage rear derailleur (and for a frame that accepts it, there is also a 9-39t cassette 11s for XD/XDR rear hub usuable with a Shimano GRX derailleur).

I think you need to speak for yourself. For many, including myself, a 11t smallest cog and cogs beyond 42t are useful and adequate. Racing and speed may be your call. It is not not mine. Your terrain and uses are not mine terrain and uses. Highest point in Belgium is less than 700m. I was born at 1,600m. Highest point here is 3,100 and it's volcanic so there are steep river ravines to traverse everywhere. We need not discuss, of course, the great inefficiency and rapid wear of 9t cogs.

As I wrote, 52x11 on the Birdy is only 6.76m which is very short.

The Riese & Müller Birdy has 7.86-2.21m with a 9-32t cassette, a Brompton 6s with BWR 7.95-2.63m.

Neither the Birdy nor the Brompton are race bikes but nevertheless, their manufacturers judge that 7.86 and 7.95m are good for their bike. But maybe these manufacturers are incompetent ?

Shimano had Capreo with 9t smallest cog, SRAM introduced 10t cogs for both road and MTB on all their drivetrains but maybe Shimano and SRAM are incompetent too?

R&M Birdy’s 32t does 2.34m and not 2.21 according to my calculations. 6 speed Bromptons sold in Istanbul have 44t chainring as standard to provide shorter gears for climbing, so the Brompton 6 speed range I have is 2.33 to 7.05m. While I found 7.05m to be plenty for speed on my Brompton, 2.33m is still not short enough for me.

Hence I need shorter range and will be adding 39t chainring to Bridy which will provide 1.75m on 32t. Pretty awesome range I’d say, 1.75t to 6.49m.

I think discussing what bicycle manufacturers put on their bikes is pointless, users are free to modify their bikes to suit their needs. I bet this chainring wasn’t installed by R&M, yet rider felt such modification necessary to suit his needs.


https://cimg3.ibsrv.net/gimg/bikefor...500b5e3a1.jpeg

Its because like me, you changed the tires from 40mm wide to 50mm wide (Keuzotter gives also 2.21 for 52x32 with 40mm tires) and for this reason, I moved to a 50t chainring.

With the original 9-32 cassette and 42t chainring you can have 6.7-1.87, not so far from what is obtained with a double chainring.

Could be a good choice if we would have hubs/cassettes available.

Perfect drivetrain for Birdy would probably be rear hub + belt. Belt for Birdy will be just perfect as it doesn’t have to go through the rear triangle. The biggest challenge would probably be how to figure out a tensioner for belt while folding. As far as I know belts are not supposed to be bend in the opposite direction.

The benefit of the belt is limited, current belt last not as long as older ones.

And belt have a lower efficiency than a chain.

Last point, there are no small cogs for belt like for a chain which is a problem for a small wheel bike.

Tensionning is also a problem, not only for folding, but also because the distance between crankset and rear wheel axle changes when the rear suspension works.

For the hub, Rohloff is excellent and compatible with small wheel. That's what I have on my Brompton with 54x13 it gives about 1.5m-8.0m gear inch with 14% perfectly equal spaced speed. Rohloff also allow to switch speed while pedaling with power which isn't possible with other IGH and isn't too heavy (actually a non disc Rohloff with some small weight savings has the same weight as the Brompton 6s BWR).

I could take a Birdy with Rohloff but to minimize the weight, I preferred a derailleur that with my current setup 50t front 9-34t rear provides a enough range.

Could someone advise torque values for these two screws?

https://cimg7.ibsrv.net/gimg/bikefor...65c8099e8.jpeg

I checked that one, it’s fully retracted and doesn’t touch the frame when rear wheel is folded


https://cimg8.ibsrv.net/gimg/bikefor...d75ce3712.jpeg

there is also room between the wheel and the frame

https://cimg1.ibsrv.net/gimg/bikefor...9e5187ff9.jpeg

but something still prevents it from going in further and I can’t find what it is. Not the chain tensioner.

Maybe check for cables/wires binding and being stretched? Whatever it is, you'll find it eventually :)

This used to be the gospel and many still believe it. But several belt bikes are now being offered with variable chainstay length and a belt tensioner, with "back-bending" of the belt. R&M makes them, and there are also some offroad bikes. I'd definitely like a belt for my Alfine 11 Birdy. (Now I use a chain and chain wax for cleanliness, which works, but must be applied frequently.)

Some factors I think are preventing a belt Birdy:
- R&M don't seem interested in developing the Birdy further, with their massive focus on mid-drive ebikes. Pacific focuses more on lower price models, and have licensing limitations.
- Belts require a straight beltline. The Birdy suspension pivot is slanted, so as the suspension moves the beltline changes, and the rear & crank axles change from parallell to non-parallell. The deviations are small, but perhaps enough to either cause problems or keep R&M from wanting to experiment with it.
- As you say, a belt tensioner that works when folding, and also when riding, can be difficult to design. I guess it needs to be quite strong and stiff.

The same folding problem happens as shown on the picture when the chain is not on the smallest cog.

Can you check if its not the chain on the cog that prevent to fold enough ?

For the belt tensionning while folding, Kinetics makes Brompton with belt drive and use a modified Brompton tensionner. I always wonder if such a system provides enough tensionning for a belt ?

Do you have any detail on this? Anecdote: My 4 years old gates belt drive mid-motor ebike with nuvinci has passed 14 000 km now, with no sign of belt damage/wear, and no cleaning done. Ridden year round in sun/rain/snow. I don't know how long it will last, but even if it suddenly snaps tomorrow I'll be happy with it.

Maybe true for most of the riders that use belts. But for a strong enough rider, belts are more efficient than chains. I don't recall the exact wattage point where the belt wins, but it's been measured thoroughly. Of course in muddy/dusty MTB use, or with poorly maintained rusty chains, belts can win even with quite low wattage, I'm sure. Belts are an excellent option for the right uses.

For the Birdy, yes, because of the slanted pivot axle and the folding limitations. But variable chainstay length and belt tensioning in general is no longer a dealbreaker with belts, several manufacturers make such bikes now including R&M.

This is no longer true, I think. For sure the NuVinci / Enviolo can shift with power (though I would only recommend this hub for ebikes because of its low efficiency). And there are several new-ish options now like the Kindernay and the 3x3, made for MTB and/or ebike use. Are we sure those can't be shifted with power?

Anyway this shift-with-power thing is overrated, I think. With derailers it accellerates cassette/chain wear, so there's a benefit to reducing power anyway. Those who haven't tried IHG's may think the issue slows down shifting, but I'd say that's not generally the case. My Alfine 11 shifts instantly, always, and I don't have to stop pedaling, just reduce pedal speed. With derailers the shift speed depends on how fast the wheel/cranks are rotating. If climbing a tough hill in the 2nd lowest gear and I need to shift down, that shift can be very slow, while at high speed the shift is quick. (I ride with chains, belts, derailers, Alfine 11, Nuvinci, and Sturmey-Archer 5-speed. Each of those systems are excellent for their uses.)

Interesting option. It looks like they use a belt snubber. With that they can get away with less tension.

https://cimg6.ibsrv.net/gimg/bikefor...1c41c7200.jpeg

This is an 11~36 with GS derailleur. I used to run an XT SGS derailleur and 18” wheels, and was always bashing the derailleur. I swapped to 20” wheels and the GS derailleur and no more bashing. The bike doesn’t fold quite as tightly as before, but still fits in a Birdy bag.

Makes sense.

What's the biggest tire size that can be fitted on a Birdy with a 406 rim?

35x406 without mudguards (Continental Contact Urban 32x406 on 25mm inside rims = 35mm measured width).

Pacific Cycles deliver the R20 11SP with Panaracer Minits Tough 32x406.

I didn't had any folding issue but it was with the Titanium Birdy, not Birdy III. It might be different with a Birdy III but I doubt about it because the overall wheel size isn't much bigger in 35x406 than in 50x355 which is the standard wheel size of the Rohloff Birdy III.
Below a picture of the folded Ti Birdy with the 32x406 Continental Contact Urban tires (and a custom carbon front mudguard+Ridea rear mudguard and easy wheels):
https://cimg1.ibsrv.net/gimg/bikefor...46bf9638cf.jpg

I figured out the problem. Chain tensioner was hitting the frame as it wasn’t installed correctly (too forward).


https://cimg0.ibsrv.net/gimg/bikefor...0e5489766.jpeg

repositioned it to face down when unfolded and now all is well. Since rear wheel folds further up fold became much smaller as front wheel spindle now goes fully underneath the derailleur. Unbelievable how much difference it made.

Is this much chain slack and position of tensioner when folded normal?


https://cimg5.ibsrv.net/gimg/bikefor...65fabc530.jpeg

No, its too much slack.

Do you have a picture including the rear derailleur when folded ?

The chain isn't the original one, could it be that its too long, longer than the factory chain was?

The Birdy can benefit from a bit shorter chain than is common/advised on other bikes, so no wonder if the bikeshop made it too long. I have it rather short on mine since the Alfine chain tensioner isn't very long, to avoid it getting slack when folding.