dynaryder

Here:

Brompton says my S6L is 920g heavier than if it was a SS(mine's the same year as the catalog). If the proper 5spd hub is 1060g,than that's a 140g difference,which according to Google is 4.9oz. That's just over a 1/4lbs. I don't know what the shifter and cable weigh,but I think it would be reasonable to guess that when all was said and done it would be about a 1/2lbs difference.

As to whether this matters,I'd say yes. Folders tend to get picked up and carried more than regular bikes,so shaving weight off is in my opinion important. If you don't care how heavy your bike is,then fair dinkum. But if I had to do over again I would've spent the extra dosh on the lightweight bits.

fietsbob

Get on the crowd funding for the All Titanium Brompton?

chagzuki

Dynaryder appears to be comparing the weight of a 5 speed hub with the difference in weight between a single speed and 6 speed, and there's no logic to that at all.

Incidently, my Brompton continues to feel far smoother since switching to a 14t sprocket. If anyone is finding the drivetrain a bit rough on a 3 speed and are using the lowered gearing then switching to 14t / 48 or 47t might improve things.

chagzuki

I'd assumed the BSR was the same weight as an S-RF3, but the bromptontalk wiki says this:

2010-Present (2013) Brompton Standard Range (BSR) Hub, (range 178%), 148mm axle
This hub was designed by Brompton itself in an attempt to create a noticeably lighter hub than the Sturmey Archer SRF3
The design makes use of various standard SA-parts used in original SA-hubs, its inners are interchangeable with the Sturmey Archer SRF3
The hub is produced specially for Brompton by Sun-Race/Sturmey-Archer .


So the internals are the same, but somehow the hub is significantly lighter? The shell is already alloy, I don't see what scope there is for weight saving. If anyone can weigh a BSR hub I'd be curious to know the result. Actually I suppose interchangeable inners doesn't mean they're the same, perhaps they shaved a bit off the planet cage.

In that case the 5 speed will be perhaps nearly identical in weight to the 6.

fietsbob

so nobody has both hubs, and weighed them in person .. just quoting stated data..

entertained ..

smallwheeler

also, which hubs are being compared? bsr? bwr? aw? s-rf3? s-rf5? x-rf8?

silly thread..

chagzuki

It's useful to me, I like to know the specifics of hub designs. It's also interesting to see that an S-RF3 was 975g a few years back but the current version is apparently 1020g. Incidentally, old AW internals in an alloy shell ought to weigh around 900g, presumably the lightest option.

dynaryder

I'll take an all-carbon.

chagzuki is trying to make a comparison using the specs for the BSR,when 6spd Brommies use BWR hubs,and there's no logic to that at all.

smallwheeler

also, comparing the bwr 6 speed to a sturmey 5 speed isnt an appropriate comparison.

chagzuki

Please, don't compare my comparison to yours.

fietsbob

Mine will rise to the occasion if properly stimulated

CbadRider

TMI.
You might want to confine comments like this to the other kind of forums you visit.

fietsbob

interpretation is a liberty of the reader .. my liberating levity has been known to do that (X)


i'm not the one who posted the blue pill picture.. that was their leaping to another conclusion..

smallwheeler

what blue pill picture?

fietsbob

Mod's removed it..

kamtsa

Locking this thread.

DoubleDiamonDog

Late again - I miss all of the fun...

landhere

Same here.

smallwheeler

oh, you!

dynaryder

FYI folks,I sent an e-mail to Brompton customer support and got a reply:

"Thank you for getting in touch. Yes, the current 6 speed set up would be slightly lighter then the 5 speed."

So there it is from Brompton;the 3spd hub/2spd der is lighter than the 5spd hub.

chagzuki

They would have to be referring to the entire bicycle, i.e. the MkII vs MkIV, since in terms of hubs alone the BWR would have to weigh 880g for the two to be on a par, and I don't believe that's possible. I'd also wager that the BWR is heavier than the SRAM T3.
I aim to get the proper stat, but so far it's not been forthcoming.

chagzuki

https://www.velovision.com/showStory.php?storynum=946

They seem to think the hub is 940g without sprockets. That sounds about right and is significantly lighter than any other SA 3 speed hub. So with 120g difference between it and the S-RF5 you have to then add extra sprocket, cable, jockey wheel pusher mechanism and shifter, which according to the brompton website is around 180g (that's the difference between 3 and 6 speed weights. Which means something like a 60g difference overall.

The old Sprinter hubs had steel shells so they'd be 100g heavier than the current type, in that instance they'd be heavier overall.

smallwheeler

so, please inform us all - what is your final conclusion regarding this highly pressing and important issue? or, is your final statement about this issue, "well, if it was completely different, it would be heavier.. so, there!"

chagzuki

My general conclusion is that it's very frustrating that hub manufacturers haven't focussed on improving the 5 speed designs that have been around for a long time, and which could cater to the requirements of folding bikes perfectly. The medium ratio Sturmey Archer hub never worked as well as it ought to and the current version has overly large jumps between gears. The Sachs/Sram range of hub gears are internally very precise and as a result the internals are very light (lighter than SA equivalents), but since their intended use was cargo/dutch style bikes they stuck with a heavy steel shell. The T3 is still only around 930g.
So Brompton could have worked with SRAM to produce something similar to the P5, which has evenly spread ratios and which with an alloy shell could be very light. There are options for manufacturers to create lightweight and extremely efficient hubs for folding bikes that have more than 3 gears but so far it's not happening, which is a PITA, since the typical hub weight of 1.5kg or so for a nexus or alfine is really far from ideal for something that needs carrying.

tcs

Chagzuki is frustrated! Something must be done!