Rear hub/cassette upgrade recommendation for Birdy

[CEBEP]

I decided to get a Birdy so my Brompton wouldn’t feel lonely at night. I had a good deal for R&M Birdy Touring and said what the heck.

It comes with Sunrace rear hub and cassette which apparently compatible with nothing else. In another forum user reported hub braking on him twice as the metal was too thin. Birdy is 18 inch wheels, will put Big Apple 50-335 later on. Chainwheel is 52T. Rear cassette currently installed is 9-32 which gives it more or less compatible range with my Brompton.

My Brompton is 6 speed with 44t chainring. This is common drivetrain setup for Bromptons sold in Istanbul as we have hills everywhere. If my understanding is correct, the gearing meters of development on my Brompton would be 2.32m on 1st gear and 7.03m on 6th.

Now I’m looking for alternatives to upgrade rear hub/cassette for Birdy. Rear hub is 135mm with disk brake and while I was recommended on other forum to look at XDR hubs as it can accept smaller cogs I can’t find them in local market and imports are problem’s these days. I discussed with my mechanic and he recommended Shimano hub with 11-36 cassette. Now 36 cassette is a welcome addition to hilly roads here in Istanbul but I’m wandering if 11t smallest cog will be small enough for soeed? It’s all subjective of course, I’m not going to race this thing but am comparing to Brompton. According to my calculations it will give 6.5 meters of development.

What would community recommend as the rear hub/cassette upgrade? Shimano is most popular brand here in Turkey but I’ll be happy with alternatives if available.

 

[LittleWheelsandBig]

Sounds like you have a Capreo-compatible cassette and freehub. Moulton sell Capreo-type cassettes but they are very rare otherwise.

Swapping to an 11t cassette lowers your top gear by 18%. The standard Birdy chainring used to be a 56t, rather than the 52t you have (about 7.5% larger). I am uncertain what is the biggest chainring you can comfortably fit on a Birdy.

The larger tyres will raise your top gear a little too.

I guess you will want to reuse the existing rim, so your new hub will need to match the existing spoke number.

 

[berlinonaut]

I am uncertain what is the biggest chainring you can comfortably fit on a Birdy.

Space is not an issue.

Don't know the exact size but it looked pretty impressive and the rider was on the faster side of the pack.

 

[berlinonaut]

I decided to get a Birdy so my Brompton wouldn’t feel lonely at night. I had a good deal for R&M Birdy Touring and said what the heck.

What year? New or used?

It comes with Sunrace rear hub and cassette which apparently compatible with nothing else. In another forum user reported hub braking on him twice as the metal was too thin. Birdy is 18 inch wheels, will put Big Apple 50-335 later on. Chainwheel is 52T. Rear cassette currently installed is 9-32 which gives it more or less compatible range with my Brompton.

My Brompton is 6 speed with 44t chainring. This is common drivetrain setup for Bromptons sold in Istanbul as we have hills everywhere. If my understanding is correct, the gearing meters of development on my Brompton would be 2.32m on 1st gear and 7.03m on 6th.

This is your Brompton in comparison with your Birdy (9-32 on the Birdy but probably not the cassette you have - so spread is correct while gear steps probably not):

https://ritzelrechner.de/?GR=DERS&K...evelopment&GR2=BBWR&KB2=44&RZ2=13,16&UF2=1330

Now I’m looking for alternatives to upgrade rear hub/cassette for Birdy.

Why?

 

[Sharky]

How old is the Birdy? Did you buy new?
It must come with some kind of warranty, so the old saying "if it ain't broke - don't fix it" probably applies.

Reviews from disgruntaled users are probably greater in volume than satisfied users, so I would take them with a "pinch of salt" and rely on your own evidence of failing components.

Good luck and happy cycling

 

[CEBEP]

What year? New or used?

This is your Brompton in comparison with your Birdy (9-32 on the Birdy but probably not the cassette you have - so spread is correct while gear steps probably not):
View attachment 650140
https://ritzelrechner.de/?GR=DERS&K...evelopment&GR2=BBWR&KB2=44&RZ2=13,16&UF2=1330


Why?

I thought I replied but apparently reply didn’t pass through. It’s new R&M Birdy Touring, don’t know the year probably 21/22 but it’s the latest frame.

Already described why in my first post.
My mechani suggested to go with Shimano XT 10s hub and 11-36 cassette.

36 speocket is a welcome adoption for hilly Istanbul, but with 11 I’ll need to see. Maybe will buy bigger chainring if 52 will not be fast enough.

 

[T4tomo]

I'm confused. "Why?" still hasn't been answered

new, so current cassette isnt worn out. You have reduced the gearing on brompton so presumably that suits your terrain & riding? Birdy has similar low end of the range, and an extra high gear, but you want to make it both lower & higher / faster at the same time ??

rather than go down an expensive route of changing hubs & cassette, i'd embrace the 9T of the capreo. If you need it lower geared than brompton fit say a 48t chainring, then you will have a lower bottom (2.16) but still have a higher top gear than your brompton (7.68)

 

[CEBEP]

Yeah, the Why..

I can keep using 9-32 of course untill cassette will wear out and then I’ll need to change the whole system anyway. That’s considering that by then all Shimano components will still be available in the local market considering supply shortage of basically everything these days. That’s if the hub will not fail on me braking derailleur along. Sunrace hub/cassette are not available to buy locally and probably nowhere else except R&M Germany. I’m not talking about lack of warranty for anything I’ll buy from abroad.

Turkey have new regulation that any package above €150 of value must undego full import customs procedure which normal person can not do. Long story short I can’t order from abroad anything above €150. And if 32t will not be high enough I don’t see a reason to invest in 48 chainring knowing that eventually I will have to change the hub/cassette. Changing the hub with cassette will cost me about €140 + rotor and cost to rebuild a wheel and I will have access to Shimano cassettes which will most probably be always available at good prices locally, all parts will have 2 year warranty.

 

[CEBEP]

Space is not an issue.


View attachment 650139
Don't know the exact size but it looked pretty impressive and the rider was on the faster side of the pack.

There is a cable retention device under the chainring so there is definitely a limit on which size can be used. Or else it may effect the fold.

 

[berlinonaut]

Turkey have new regulation that any package above €150 of value must undego full import customs procedure which normal person can not do. Long story short I can’t order from abroad anything above €150.

You should look at the maintenance plan inside the manual of the Birdy. Possibly you will be unpleasantly surprised. The Birdy is a pretty expensive bird.

And if 32t will not be high enough I don’t see a reason to invest in 48 chainring knowing that eventually I will have to change the hub/cassette. Changing the hub with cassette will cost me about €140 + rotor and cost to rebuild a wheel and I will have access to Shimano cassettes which will most probably be always available at good prices locally, all parts will have 2 year warranty.

If your Brompton is good enough on hills I still don't get your desire for change on the Birdy. Also you should be aware that on a small wheeled folder derailleurs are tricky: The bigger the spread the longer the derailleur cage needs to be - this is not unlimited, at some point it may have not enough ground clearance. As far as I know, from factory you already have to to shift to the low gear before folding (at least it used to be lke that). So the better way is in most cases to tune the chainwheel. If you need more spread due to hills the Rohloff is the king's solution, the S/A RK3 is a more economic solution.

 

[CEBEP]

You should look at the maintenance plan inside the manual of the Birdy. Possibly you will be unpleasantly surprised. The Birdy is a pretty expensive bird.
View attachment 650159


If your Brompton is good enough on hills I still don't get your desire for change on the Birdy. Also you should be aware that on a small wheeled folder derailleurs are tricky: The bigger the spread the longer the derailleur cage needs to be - this is not unlimited, at some point it may have not enough ground clearance. As far as I know, from factory you already have to to shift to the low gear before folding (at least it used to be lke that). So the better way is in most cases to tune the chainwheel. If you need more spread due to hills the Rohloff is the king's solution, the S/A RK3 is a more economic solution.

I’m not too happy with my Brompton on hills, any serious climb is becoming a little bit an issue. May be related to few things: firstly high rolling resistance of Marathor Pluses I have + less efficient drive train of Brompton (hub). And secondly my fitness condition, I’m not training for long rides and use the bike for recreational purposes. Though I’d like to go on touring. For roders who are better fit than me my current Brompton gearing could be enough for hills. But every time I go in hill I’m thinking of higher gear.

I’m aware of maintenance plan, don’t know how it helps with my question though.

Sturmey Archer would not be my first choice should I decide to go with hub. Alfine 11 would be my choice as it has widest range than any cassette.

Rohloff Birdy is an overkill for me, not to mention insane price and very long lead times. I don’t want even think about how much it would cost to fix should the hub brake.

Hence will be using standard and easily available Shimano hub, cassette and derailleur.

I’ll be using stock derailleur coming with Birdy which will be fine with 36 cassette. What you’ve mentioned about using longer derailleur is true but if user will go wider on low gear. 36 should be low enough for me.

 

[berlinonaut]

I’m not too happy with my Brompton on hills, any serious climb is becoming a little bit an issue. May be related to few things: firstly high rolling resistance of Marathor Pluses I have + less efficient drive train of Brompton (hub). And secondly my fitness condition, I’m not training for long rides and use the bike for recreational purposes. Though I’d like to go on touring. For roders who are better fit than me my current Brompton gearing could be enough for hills.

On hills rolling resistance is not really a relevant issue due to the low speed. The Brompton's drivetrain ist not really inefficient - 3-speed hubs are not bad. This probably nails it down to your fitness mainly (if the drivetrain is clean and tirepressure is high enough).

But every time I go in hill I’m thinking of higher gear.

You probably mean lower gear.

Sturmey Archer would not be my first choice should I decide to go with hub. Alfine 11 would be my choice as it has widest range than any cassette.

In Terms of efficiency not the best choice, reliabiliy was an issue in the beginning. It may have become better in the meantime - don't know. If you are interested in the Alfine 11 I'd defintively recommend a test ride. I really dislike this hub. If feels like pedaling in rubber, the small gear steps are fine but on the traffic lights you can only shift one or two gears at once and the 30% step between 1st and 2nd is useless.
Regarding efficiency:

(Source: https://fahrradzukunft.de/20/wirkungsgradmessungen-an-nabenschaltungen-3)

Rohloff Birdy is an overkill for me, not to mention insane price and very long lead times. I don’t want even think about how much it would cost to fix should the hub brake.

The Rohloff is basically bullet proof and the most efficient and most robust hub there is. It is is expensive but in no way "insane". You pay for quality. My oldest Rohloff ist about 20 years old with countless kms on the clock and runs like a bee. I do own a handfull of Rohloff bikes and never ever had any relevant problem with any of it. Retrofitting is easy and you get massive spread w/o derailleur issues on a folder. As the chain lasts more or less forever as does the sprocket: The more you ride the cheaper it gets in comparison to a derailleur setup. But understandable if the entry price seems too high.

Hence will be using standard and easily available Shimano hub, cassette and derailleur.

I’ll be using stock derailleur coming with Birdy which will be fine with 36 cassette. What you’ve mentioned about using longer derailleur is true but if user will go wider on low gear. 36 should be low enough for me.

Good luck and tell us how it works out in practice and if it really solves your hill problem. As @T4tomo I am not convinced that you go into the best direction with switching hub, sprockets and possibly derailleur on a brand new bike of massive complexity.

 

[berlinonaut]

There is a cable retention device under the chainring so there is definitely a limit on which size can be used. Or else it may effect the fold.

If I remember correctly the chainwheel in the pic I posted was 70t or 72t. If you need to get bigger than that you will have a different problem anyway.

 

[CEBEP]

@berlinonaut can Rohloff hub be bought separately to convert Birdy later on? I’m not sure they sell stand alone hubs.

 

[berlinonaut]

@berlinonaut can Rohloff hub be bought separately to convert Birdy later on? I’m not sure they sell stand alone hubs.

Absolutely. Buy a hub in the correct config, build a wheel and you are done.