Hello, I would be grateful of feedback on the following: I have a mk3 Birdy using the Nexus 8 gear hub. However, even on first gear, it is difficult to climb steep hills. I read some threads that it is possible to replace the front chain ring. Could anyone make a recommendation on the replacement chain ring? Thank you for your help

Rather than disturb the chainring with its associated chain guards how about using a bigger sprocket on the hub? The supplied sprocket is 16T so an 18T sprocket reduces the gearing by about 12% which is roughly the difference between the Nexus 8 gears (excepting the 18% gap between 2nd and 1st gears) and would put the new top gear where 7th gear is currently. You might also need a new and longer chain (9 speed) but it would be worth trying the larger sprocket with the chain already on the bike. A new sprocket and chain will be no more expensive than a new chainring. An 18T sprocket on the hub gives about the same gearing reduction as fitting a 46T chainring. You could fit an even bigger sprocket if you want even lower gearing but remember that what you gain at the bottom you lose at the top.

I've got an ongoing project to try and fit dual chainrings and a front derailleur on a Birdy 3 with Nexus 8 hub in order to widen the gearing range but keep finding new obstacles.

Feedback to JRat
 

Thank you for your response on my question re: Gearing / Chain Ring / Nexus Gear Hub. I really appreciate it. I will go with your recommendation, and I will send photos and feedback once I have it completed. Thanks again

Adding front derailleur and having two chainrings that extend the gearing range is the best option because increasing the sprocket will reduce the upper range.

Some pictures of a factory two double chainring Birdy 2 race.
https://cimg9.ibsrv.net/gimg/bikefor...3afe1d8637.jpg
https://cimg1.ibsrv.net/gimg/bikefor...877fe436a1.jpg
https://cimg2.ibsrv.net/gimg/bikefor...15b5dfcc29.jpg
https://cimg3.ibsrv.net/gimg/bikefor...fc07ed35cc.jpg
https://cimg5.ibsrv.net/gimg/bikefor...7202ea5afd.jpg

https://cimg4.ibsrv.net/gimg/bikefor...522f795dca.jpg

I have abandoned my project to put a front derailleur on the Birdy City. Getting the bottom bracket unscrewed to enable moving spacers from left to right side was proving to challenging as it's not just the matter of having the right tool but also holding the tool in place while applying sufficient force.I didn't want to make a mess of the bike only to verify that moving the spacers isn't enough to shift the chainline enough to suit the derailleur's range of movement. I wonder if Birdies built with a front derailleur are fitted with a longer crank axle in order to get the chainline further out.

I've therefore decided that the Birdy City will have to be rehomed who doesn't want to tackle big hills and have got a Birdy Rohloff on order (I was offered an attractive discount on a new one which helped make the decision). I'll be interested to compare the crank axle length on the two bikes as the Rohloff hub has a wider chainline than the Nexus hub.

Another pending project, to fit ergotec AHS handlebars to a Birdy so I have more variety in hand and body positions, will wait for the Birdy Rohloff which should be early next week.

You need to bolt the tool to the BB spindle, to keep it in place. This VAR tool comes with all provisions there and for other you need to take care of this yourself.


https://cimg7.ibsrv.net/gimg/bikefor...2fbc9c9887.png

Birdy are equipped with external bearings !

I am curious to know if R&M adapted the chainline for the Rohloff Birdy compared to the Nexus 8 Birdy.

Replacing your Nexus 8 Birdy by a Rohloff Birdy is of course a radical solution and change, the Rohloff hub is a completely different category of hub than a Nexus 8 !

Hi guys. I have a birdy GT and have recently installed a bigger chainring. For next upgrade for speed I am looking to change the cassette to <11t to either sram force or 3t bailout which both requires xdr drivers.

Does the stock wheel allow me to install a xdr driver or do i need to rebuild a new wheel for this?

You need to rebuild a new wheel with a new hub and (most probably due to a different length) new spokes.

Hey, has anyone here re-laced their 3rd gen Birdy disc front wheel? If so, do you have the measurements of the front disc hub by chance?

The only Birdy disc front hub measurements I have is for the front dynamo hub. For the wheel set I made, I used Hubsmith Birdy disc front hub with straight pull spokes (I couldn't find the same front hub as mounted by Riese & Müller).
https://cimg3.ibsrv.net/gimg/bikefor...9087d92ae0.jpg

I can confirm that the chainring offset is different between the two bikes as they should be as the Nexus hub has a smaller chainline offset than the Rohloff hub. The crank length appears to be the same (measured by tape and not calipers) but the Rohloff Birdy doesn't have the spacers on the left side of the bottom bracket. I assume they are on the right side but it's difficult to see as that bike has the extra chain tensioner that's clamped to the bottom bracket.

I'm planning, when the weather is amenable for bike fiddling, to try fitting the derailleur clamp and derailleur onto the Rohloff birdy to find out, as a matter of curiosity, if it will fit OK with the bottom bracket and cranks shifted to the right.

I'm well aware that the Nexus and Rohloff hub gears are somewhat different, both in performance and price. The new Birdy is my third bike with Rohloff gears (but I must rehome one of the others as it hasn't been used for nearly a year). The Nexus hub has the disadvantage (apart from the smaller gearing range) of the twist shifter turning in the opposite direction to the Rohloff shift so, when I tried the Nexus Birdy, I kept shifting gears in the opposite direction to what I wanted.

The Rohloff Birdy has been both up and down the worst hill on my local cycling circuits. We got up the hill with a couple of gears to spare but 40mph (>60kmph) going down was, I felt, plenty fast enough as the steering was feeling a little twitchy and lacks the inherent gyroscopic stability of a full-sized wheel. I didn't try going up that hill with the Nexus Birdy as I knew that I would run out of gears.

Thanks for the interesting information.

On a Birdy 3 Touring with 10s derailleur, there is a 1mm spacer on the left side.

Like on your bike, I cannot see if there is a spacer or not on the right side due to the chain tensioner clamped on the bottom bracket.


https://cimg3.ibsrv.net/gimg/bikefor...f90efdabf9.jpg

I'm still under the 10 post limit to be able to post photos.

I have my Birdy Rohloff ready for action with the Humpert Ergotec AHS handlebars which provide extra comfort on longer rides by allowing different hand and body positions (photo fotthcoming when I've got enough posts). However, it's necessary to slacken the clamp and rotate thees bars to the vertical position to get a compact fold. The bottle cages are fixed by SKS bottle cage mounts which have adjustable straps and quick release latches so easy to remove for transport. I've also got a pair of Carradice front pannier which fit nicely onto the front rack and there's also the option of a bag on the rear rack.

I did some measurements of the bottom brackets and cranks on both the Birdy City and the Birdy Rohloff. Both cranks are 139mm across the ends. The chainline on the Birdy City (blue bike) is 47.1mm (measured by calipers between centre of chainring to the far side of the 40mm dia seat tube then subtract 20mm to get the centreline) whereas the chainline on the Birdy Rohloff is 50.8mm. This is significantly less than the 57mm recommended by Rohloff for the 13T sprocket on a splined carrier but that's another issue. There might be small errors in my measurements due to estimating the centre of the chainring axis.

I also did a trial fitting of the front derailleur on the Birdy Rohloff.The larger chainring is just within the limit of the cage when in the inner position. However, I did not spend time fitting the smaller chainring to see how it would line up. It might just work but I'm not going to spend time investigating.

I measure also about 51mm on the Birdy Touring 10s pictured above.

This distance is to the middle of the chain place on the single chainring (which is not a correct measurement for a double chainring setup, the distance must be measured to the middle of the two chainrings).

It seems to me that the crankset mounted on the Birdy Touring is actually made for a double chainring setup, I see the place to put the inner chainring.

I measure also about 51mm on my Birdy titanium factory equipped with a compact 52-36 crankset and a braze-on Shimano 105 front derailleur.

So if the Ridea front derailleur clamp is well dimensioned, it should be possible to mount a front derailleur and second inner chainring on the Birdy Touring.

Most chainring spiders are made such that one chainring can be fitted on the inside and another on the outside with the spacing correct for a front derailleur). The Shimano Nexus hub has a relatively narrow chainline (the shift mechanism is between the sprocket and the drop-out) which explains why the cranks and chainring are moved to the left.

I completed the following:
Back sprocket: changed the 16T to 19T
Chain: the original chain was too tight, so I installed a new KMC X11 chain.

Outcome: Absolutely great! For the routes that I am riding (city / hard gravel / hills) the lower gear ratios as a result of the 19T sprocket make a huge difference, I can now use the full gear range of the Nexus 8. Thank you all again for your help on this!

Thanks for the update. The original chain might have felt tight due to the springing of the chain tensioner but, if you've left some slackness in the new chain then check that it doesn't come off when the bike is folded.

Yes, most spiders are made for two chainrings but the Birdy is supposed to be a single chainring bike. On the Brompton, also single chainring, the spider is made to accept only one chainring.

Alfine are the same, for the same reason, also narrow chainline hubs.

The total opposite to the Rohloff that has a wide chainline (the original application considered by Rohloff was MTB but the hub was never a success for that purpose and found its market in high end everyday and travel bikes).

Birdy City (9SP STD) and Classic came with a square taper crankset which is not suitable for direct double chainring upgrade. Birdy Touring, 10SP Sport, GT and Rohloff have a wider chainline is because it's using the hollow crankset that provides a wider chainline. Many of my friends including myself have been using our hollow crank Birdys to do double chainring setup. That's the cheapest way to get a double chainring setup on Birdys.

The chain will scratch the rear fork when we use the square taper crank to do double chainring setup.

Also, Birdy with these BSA BB usually have 1x2mm spacer installed on the non-drive side and 2x2mm spacers on the drive side. That provides enough space for the 2nd smaller chainring t be installed. Funny enough the expensive Ti 2019 didn't have a single piece of spacer installed on the BB. That causes the chain to rub against the FD on Front-Small plus Rear-Large combination. I have no idea what was Pacific Cycles thinking in making such a low level mistake on a premium bike, or is it that they are taking customers for granted because we all paid to pre-order the bike?

I think there is a misunderstanding about the type of Birdy.

JRat had a Riese & Müller Birdy City, not a Pacific Cycles Birdy 9SP STD.

The Birdy City from Riese & Müller has a Shimano Nexus IGH and like all R&M Birdy it has a hollow crankset.

The 2019 TI Birdy has a totally different crankset, its a FSA SLK-Light with integrated axle. Its not possible to use spacers with this crankset.

And also, the Ti Birdy frame is totally different from the Birdy 3 frame. All frame dimensions are different, even the wheel base is different, its about 20mm smaller than the Birdy 3 wheel base (I have a R&M Birdy 3 Touring and a Pacific Cycles TI Birdy 2019 and compared the two frames).

Good to know something new everyday. Thanks!

As for the Ti 2019. For those different things like the wheel base length and such, the drive chain system is basically the same. Same BB shell width, same rear wheel drop out width. Thus the chainline should be the same like any ordinary B3. And yet they chose that crankset that will cause the chain to scratch the FD. I can't take it as simply they are different so the problem happens on a premium bike.

What I wanted to say is, basically PC shouldn't have choosen that crankset from the beginning.

They choose an high end race road crankset (which is almost the only high end component on this expensive high end bike) with the chainline of a race road bike but indeed they should have adapted the frame.

Now, the rest of the transmission isn't adapted to the small wheel size too.

The 11-28 cassette with the 52-36 chainring provide a too short gear inch. They should have mounted a 9-32 cassette like R&M does (or at least a 10-something cassette).

I haven't experienced the chain problem you mentioned because I immediately changed my wheels and have a rear wheel with a Hope RS4 hub with XDR freewheel and a 9-32 cassette and never need the very short 36 front - 32 rear combination.

Hi, I'd like to ask the experienced Birdy riders here, please.

I just got a used Birdy 2 this afternoon. It's got hubsmith wheelsets. I just noticed that the front wheel spokes are asymmetrical, dished like a rear-wheel like it was meant for the rear but put on the front. When I rode it, it seemed that the wheel isn't in the centre but slightly off centre. Is that normal?

I've been riding foldies for the last 15 years. Had Dahons, KHS, Bike Fridays, Speed One, and this is my first Birdy. I've never seen anything like it on any other foldie before.

That doesn't sound right to me!

I have Birdy front wheels laced with this Hubsmith front hub for Birdy disc the spokes are symmetrical and must be symmetrical to have the wheel centered (the front hub is specific for Birdy disc because the front disc is on the right side and closer to the center of the wheel than a standard disc front hub. Width is standard 100mm).

Birdy with rim brakes use a standard 100mm front hub.

Thank you, for your response, yangmusa and jipe.

I can see it's centred but dished (and yet it seems to be riding off-centred). Perhaps its to accommodate a disc rotor.

thanks, jipe, for the link to the pic. My hubs don't look like that. And I don't seem to be able to find which hubsmith model it is .

I think I'd better find out which shop the previous owner brought it to and ask the mechanic there. Many thanks!

Reminds me of a little sports car... Like a Mini Moris... Fun Fun Fun!

Schwalbe Blackjack size?
 

Anyone here has a Birdy with Blackjacks? I measured mine (freshly mounted) and they are 41mm wide, not 47mm as advertised. Just wondering if it's just mine?