glye

The problem with all of these, from the R&M point of view, is that the cassettes are proprietary from a small-ish vendor, same as for Sunrace. So that's a business risk. Unlike the Sunrace option, the XD(R) hubs are standardised, and can be much stronger than the Sunrace. But the 3T / E*THIRTEEN cassettes are expensive, more than Sunrace afaik. The derailers might be more expensive too, not many road derailers exist that can go to 42t and do it well. So it's a tradeoff for R&M, neither option is ideal.

Yes, though for most people who accept the weight and drag of an IGH, I think the gear shifting issue isn't a big concern. There's a benefit: My Alfine shifts much quicker than anything else I've tried (and I've tried Rohloff) except the auto-shifting 2-speed SRAM Automatix. And of course it can shift while standing still. It's a matter of taste, yes, and of the purpose of the bike.

Yes, the big range it offers is mainly interesting for those who either have a lot of hills to climb (and race down), or for those who do heavy loaded touring. Especially for the latter group the extra weight of the SA is insignificant and can be well worth it.

Jipe

Yes, these lightweight cassettes are expensive (Leonardy has also one) but its much more standardized than the Sunrace solution because the hub is now standardized, only the cassette is not.

If you do not need the 9t cog, there are SRAM XD road cassettes 10-42 from the Force 1 and Rival 1 groupset that also have the needed derailleur. These are midrange groupset, not very cheap but also not very expensive. Need to check that they really fit with a ETRTO 355 wheel.

If 10t is a little too short, there is the possibility to use a 54t or 55t chainring instead of the factory 52t. With fat tires like the Big Apple 50x355, 54x10-42 would be great.

glye

If I knew when I bought the Birdy, all the things I now know about the fragility of the Sunrace hub and the clearance problems with 11 speed mtb cassettes, and if I didn't like IGHs, I would have looked into the SRAM XD Road 10-42 option. Out of interest I checked it now, and there's a big caveat!

For SRAM Force 1, the 10-42 offering is the CS-XG-1175-A1:
https://www.sram.com/en/sram/road/se...levancy&page=1

Then I compare with MTB, where the GX 10-42 offering is the... CS-XG-1175-A1 again..?!?
https://www.sram.com/en/sram/mountai...levancy&page=2

It's the exact same cassette for road and mtb! So, is it road spaced (3.74 mm) or mtb spaced (3.9 mm)? Since 10-42 was made for mtb first, and SRAM probably wouldn't want to make its own 11s mtb cassettes incompatible with each other, my guess is it is mtb spaced. That would mean we get the same chainline problems again. So I would not recommend investing in this without knowing for sure what sort of spacing is used.

Jipe

There is the same uncertainty about the E*THIRTEEN XCX cassette. E*THIRTEEN says its compatible with Shimano and SRAM 11s but which one, road or MTB !? But E*THIRTEEN deliver these XCX cassettes with an adapter ring to mount them on the XDR freewheel which is a road freewheel body, same as for the 3T cassette also delivered with an adapter ring for XDR.

If the XG-1175 is MTB spacing it would mean that SRAM made a road group with a combined road brake-shifter and rear derailleur that has an indexing for a MTB cassette, which is also strange.

SRAM has also other 10-42 cassettes 1150, 1195, 1199 which are classified as MTB cassettes while the 1175 is classified as cyclocross/gravel cassette (same for the E*THIRTEEN XCX while there are E*THIRTEEN TRS classified as MTB) !?

50PlusCycling

Actually, mine is a Bianchi Fretta, which is a version of the Birdy sold here in Japan, it is likely that the newer versions have been redesigned since mine was produced. I only have any noticeable noise when I am using the 36 tooth cog on the cassette, it is quiet in the other gears.

50PlusCycling

The original tensioner should be one of the first things you get rid of when you get your bike. I bought an aftermarket tensioner which mounts to the bottom bracket, it is spring-loaded and supports the chain better. I can turn the tensioner on the bottom bracket to give more clearance if I use a larger chainring.

spj

The upshot of all of these discussions seems to be that if you stick with readily available components, you can swap out most of them after experimenting.

• The front chainrings are dirt cheap, available in LitePro brand for example, in different sizes for about $20 online.
• Standard Shimano cassettes and gears are also easy to alter - especially up to 36 teeth which I have on one bike. I swap individual gears quite often as my bike moves with me to different locations.
• Moving to 20 inch wheels is also easy [there are way more tyre choices at 20" 406 than 18" but they cannot be too fat or you cannot fold the bike].
• I have four birdys and I prefer to buy a cheap one secondhand, then source secondhand or sometimes new components. it is more satisfying and the equivalent of 'car restoration' I suppose.
• If buying new, I guess getting the best model is important, but sometimes you can retrofit a really expensive drivetrain that you got cheap somewhere else, and save money.
• I have a carbon seatpost and they save a lot of weight, and flex a tiny amount front to rear, but be careful - they are probably not as strong [the $70 versions from Aliexpress], although I have not broken one.
• The orange color bike you can get from Pacific cycles is really light, under 8kg without lights and so-on - it has a carbon chainring and wheels, with disc brakes. https://www.facebook.com/photo.php?f...type=3&theater [join Birdy Global Community]
• I have one 20 inch birdy at 8.5kilos with secondhand ultegra, carbon seatpost and bars, secondhand rear end and suspension, some sort of light shwalbe 1.25 tyres, and could go much lighter with a chainring and hollow axle bottom bracket. Litpro brake calipers rather than the 20 " conversion kit. That I keep in Australia these days and the terrain is pretty flat - bike is really fast. I also have a heavy 24 speed with a rack, in England, with 18x1.5 Marathon tyres, for shopping and touring over in Europe. The standard mk2 8 speed I have, 8 years old, actually has a 36 tooth low gear and 10 tooth top- this is occasionally useful.
• By the way the Marathon 1.5s roll well and are comfy - the lighter 1.35 punctureproofs seem to have more resistance, do not know why.

Jipe

The chain tensioner I am talking about is the one mounted on the bottom bracket, all recent Birdy are equipped with this tensioner that works very well. But it limits the chanring size to 55t or maybe 56t.



Standard Shimano cassettes are indeed cheap but start with a 11t cog that combined with the limited size of the chainring produce a relatively short gearing even with 20" wheels that are limited in total diameter to about 462mm (ETRTO 406 with 28mm wide tires, 28-30mm is the max with 20" wheel for the front fork).

secret_squirrel

Jipe 58T fits fine with that tensioner.

glye is correct on his statements around the 9-32 / 9-36 11 speed mods - see my comments up thread from my version of the same modding “journey”.

I would take slight issue with the proprietary comments for the Sun Race - the outsides and cassette are pure Shimano standards namely Capreo and 11 speed cassette spacing. Whilst the product is niche and limited to a couple of folding bike OEM’s Sunrace themselves are huge . I would make a WAG and suggest they are probably bigger than both SRAM and Campy from a groupset/gearing product sales volume perspective - guess who owns Sturmey Archer!

The 9 speed Sunrace kit is available from a US retailer who ships worldwide - check out Soma Fabrications in the US.

glye

I had heard rumors before about this, nice to know. Afaik Shimano doesn't make Capreo anymore, and afaik noone else makes compatible cassettes, so de facto it's a Sunrace only system, with limited availability. But perhaps "proprietary" isn't the right word.

glye

Yes, it's all a bit odd. I guess it all works for more common bikes, so long as you don't mix groupset parts. A derailer that can shift 42t cassettes wouldn't be wanted by those using 28t cassettes, in any case. But there may be intermediate cases where there is good reason to doubt. And it would make our lives easier for those of us with special needs (all small wheel bike owners, really) if the manufacturers would publish detailed compatibility specs.

glye

Thanks, another data point. Looks nice in Bianchi colour: https://www.cycleurope.co.jp/2012/bi...ty/fretta.html

Have you checked if the chain is perfectly straight when using the middle cog of the cassette? I could only have a straight chain in 8th/9th gear. If I moved the chainring any closer to the frame, the chain would rub the frame in 1st gear.

glye

Yes, most of them, with some caveats. 10-42t cassettes are readily available, but is risky for several reasons.
It is very nice to be able to use standard 100/135 mm hubs. The Brompton gearing for instance is very limited and would be hard for me to use.

Agree. I use Marathon 44-355. Would have used Marathon Plus if they existed in this size, but still no flats in 2100 km. I gave up on thin fast tires after many flats, they're not so fast when punctured... especially when touring as I do, the roads are unpredictable and flats are extra inconvenient.

Jipe

Very confusing because if you look at the SRAM page of the Force 1 groupset you can see a mix of specific Force 1 components and some Force 22 components like the brake-shifter combo which is obviously a pure road component made to index road cassettes ???
https://www.sram.com/en/sram/road/se...levancy&page=1

So, from my own experience the only thing I can guarantee is that the XD 3T 9-32 cassette mounted on a road Hope RS4 XDR hub is placed exactly at the same place as a Shimano 11s road cassette on a Shimano/SRAM 11s freewheel body and that this 3T 9032 cassette works as well as an original Shimano cassette with an Ultegra rear derailleur.

Thanks for the info.

Seeing the headroom between the tensioner pin and my 52t chainring, I didn't thought it would accept 6t more !

50PlusCycling

I have no frame rub, the chain does line up in center. I get noise from some deflection from the chain in the lowest gear on the cassette, it goes away when I shift up to the next gear.

glye

Right. So there must be some differences in frame dimensions among the Birdy's: R&M, Pacific, and Bianchi, and over time. Speculation: R&M could have made the suspension hinge slightly wider, to reduce sideways flex and hinge wear.

Anyway. Here are some shots from my ride on Constitution Day, on Sunday:


Constitution Day ride



Svarstad, Norway

Jipe

As far as I know, all frames from the same generation are the same, whatever the brand and made by Pacific Cycles.

R&M receives the frames and assemble the bikes with a different choice of components than Pacific Cycles. R&M also discontinued the Birdy World models.

For Bianchi, just a guess, but I think they are also assembled by Pacific Cycles because its only sold in Asia ??

The only frame which is really very different is the titanium Birdy designed, made and sold only by Pacific Cycles (there were 3 generations).

But there were several generation of frames.

I do not know to what generation the Bianchi belongs but its transmission is very different, its a 8s Sram PG-850 11-30T.

50PlusCycling

My Fretta has a monocoque frame, it runs Ultegra hubs and DT spokes with Alexi 20" rims, a Dura Ace 7800 crankset, and a XTR 11 speed cassette and rear derailleur. It was originally equipped with Shimano Alivio components.

Jipe

So you actually changed all transmission components wrt. the original equipment !

You now have an MTB transmission with a road crankest, any chainline problems ?

Do you have a double chainring or single on your Dura Ace crankset ? How big is it ?

50PlusCycling

No chain line issues, no rubbing, though there is some noise from chain deflection when running the lowest gear. I had run a double on the front, but switched back to a single with a 53 tooth ring. Everything was bolt-on, no modifications were necessary. The Dura Ace 7800 does not have enough Q factor to run a front derailleur on my particular frame, so it needed to be moved out a bit. I found the extra chain ring and components to be redundant, so I returned it to a 1x11 drive line, and am happy with it.

RandomHajile

Hi, first post

I bought a 2nd hand (mk1 or classic)Birdy in dark blue last month, replaced the saddle with a Specialized “The Cup Gel”(as they sold out of the expedition gel saddle)
And pumped the Maxxis Birdy tyres to 90psi and went to town on it, 40kph ect.

as well as it rolls I had to change out the tyres, seamed really limited to either the 3 from
schwalbe, or a few from BMX websites...

I ordered a pair of Big Apples and some matching 5a inner-tubes and then waited over a week and finally got them yesterday and installed them today myself. At 42psi (they rated for 30-70psi)

ive had a quick 30min 7k ride tonight and they’re fantastic! Rolls really smooth and compliments the limited suspension(shock absorbing) the bike has.

if anything it’s making me want to try out the wider, 2.2/2.3/2.4inch BMX offerings in 18inch/355 (I really wanted a neon pair of “fireballs” but sold out...)

has anyone here got any joy from BMX tyres on their Birdy?

when I installed the front big apple tyre, I removed the fender-mudguard and even then the fork had a small protruding moulded screw nub in the wheelwell that rubbed on the Big Apple tyre bang in the middle of the tread so I had to put a spacer between the fork and pumped up tyre and then adjust the quick release lugs to sit in the forks sprockets a touch towards the ground as so not to have the tread reach the forks wheelwell nub!!

back wheel was fine, I also removed the fender-mudguard as it is summer after all

Looks like they could easily take 2.2” wheels or 2.3” after I installed the 2.0” big apples, heck maybe even a pair of 2.4”s

regarding suspension, I have the stock medium red PU elastomer, it’s seams ok and not “aged” as I was expecting considering it’s a 2nd hand mk1 style.

but I am itching to upgrade to the multi-s rear shocks, as the interior picture I’ve seen online showing the mini spring and two PU units seam on the money for me, or is the u-design/Urbane Design “adjustable” rear shock better?

Anyways better stop now before I carry on, any advice would be appreciated a lot

RandomHajile

can I get a link please?

as I can’t seam to find their website online.

glye

Welcome!

Nice! Schwalbe is among the very best, and Big Apple is really good at what it does. I don't know, but I would expect BMX tyres to be a bit stiffer and heavier. They are supposed to take a lot of abuse, and the thread often goes far down the sides.

I am happy with the elastomers, though I replaced the rear red with a green (harder) as I thought there was too much sag, pedals hit the ground too easily in turns. It's good now. When I pulled off the red one, I noticed it was already bent slightly towards ground, after only 1500 km or so. I could perhaps have gained a bit of ground clearance by rotating it 180 degrees. That's something to consider for you since yours is 2nd hand, perhaps you could "renew" it that way. No tools required, just twist it.

RandomHajile

yes, I saw how easy it is to rotate it, but my red unit seams to be in good shape, no compression on the underside at all which surprised me as PU normally ages after a decade ect, maybe the seller I bought it off kept the bike in a dark cool garage

on the maxxis birdy 1.50” tyres the elastomer didn’t sag that much but I noticed yesterday that on the 2.0” Big Apples that I felt it sagging much more!

i could get the green PU as I’m sure it would make a big difference, but really want that Multi-S shock, esp if the blue/gold is still obtainable to match my dark blue frame.

RandomHajile

Yes, if they can take abuse I was thinking that would be ideal, I don’t mind it being a bit heavy, and the small range of 18” wheels I saw on sourcebmx website (I cant post links yet) most of them had similar grip/tread pattern like the Big Apples.

one has caught my eye, Cult Dehart Slicks, which are semi slick down the middle, so am thinking they could handle roads better than the aggressive bmx tyres out there