Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 06-17-09, 07:05 AM   #26
tcs
Palmer
 
tcs's Avatar
 
Join Date: Mar 2007
Location: Parts unknown
Bikes:
Posts: 4,705
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Quote:
Originally Posted by jur View Post
...while I have theorised that the efficiency depends on the gear you're in, because of the way the ratios are created!
If you're saying your theory is that the Second Law of Thermodynamics is, in fact, correct, I'll happily agree. If you're saying lubrication, quality of bearings, surface finishes, machine tolerances, tooth profiles, etc. make no difference to efficiency, I'll have to disagree.

As I understand it, the Sturmey Archer 8(W)s have three sets of single stage planetary gears and make their ratios thus:

1st gear: direct drive
2nd gear: stage C (130%)
3rd gear: stage A (148%)
4th gear: stage B (169%)
5th gear: stages A & C
6th gear: stages B & C
7th gear: stages A & B
8th gear: stages A & B & C, 325% overall


The Shimano 8s have four sets of planetaries and make their ratios as follows:

1st gear: gear set one, 52%
2nd gear: gear set one + gear set two, 52% x 122%
3rd gear: gear set one + gear set three, 52% x 142%
4th gear: gear set one + gear set four, 52% x 162%
5th gear: direct drive
6th gear: gear set two, 122%
7th gear: gear set three, 142%
8th gear: gear set four, 162%, 307% overall

Best,
tcs

Last edited by tcs; 06-17-09 at 07:10 AM.
tcs is offline   Reply With Quote
Old 06-17-09, 08:05 AM   #27
BruceMetras
Senior Member
 
Join Date: Aug 2005
Location: San Rafael, California
Bikes:
Posts: 1,888
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 21 Post(s)
Quote:
Originally Posted by ChiapasFixed View Post
I generally find the Alfine to FEEL more efficient than the Nexus redband. Perhaps this is because it is quieter, smoother, or perhaps it has to do with the fact that the Nexus is spinning 24" wheels while the Alfine runs 16" ones. Or maybe the different geometries of the bikes have to do with it.
In general, I am generally happier with the Alfine, and with the general feeling of the Tikit, generally.
But this is, of course, a generalization...
Doesn't your Joey run an extra 'spring loaded chain tensioner' that you Tikit doesn't need?
BruceMetras is offline   Reply With Quote
Old 06-17-09, 08:27 PM   #28
ChiapasFixed
hipster traffic dodger
 
ChiapasFixed's Avatar
 
Join Date: Dec 2007
Bikes: IRO Mark V Pro, home made bamboo track bike, eddy merckx corsa extra, Airnimal Joey commute, UGADA Tikit
Posts: 596
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by tcs View Post

BTW, an Alfine SG-S501 and Nexus SG-8R36 are identical in internal construction.

tcs
...but the Nexus is without disk brakes. in any case I was comparing the Alfine to my Nexus redband SG-8R25 which is alot noisier and I am sure less efficient. I did generally state that, in very general terms, this was nothing more than a generalization.

On the other hand, it should be said that the way a drive train FEELS is a big component of how happy the rider will be with the bike, and thus how efficient it will be for getting said rider from A to B (because if i dont like the bike, i am less likely to ride it). This principle of hedonics may not have direct implications on absolute efficiency of the components, but would be an important factor in relative (or functional) efficiency.

Quote:
Originally Posted by Brucemetras View Post
Doesn't your Joey run an extra 'spring loaded chain tensioner' that you Tikit doesn't need?
Yes, I actually run an Alfine chain tensioner with it, which would probably add both absolute and relative inneficiency to the system.
ChiapasFixed is offline   Reply With Quote
Old 07-23-09, 03:37 PM   #29
Joako
Senior Member
 
Join Date: Jul 2008
Bikes:
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Any updates on your replace [w] hub tcs? Is it a reliable hub?
Joako is offline   Reply With Quote
Old 07-23-09, 05:21 PM   #30
tcs
Palmer
 
tcs's Avatar
 
Join Date: Mar 2007
Location: Parts unknown
Bikes:
Posts: 4,705
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
The replacement hub arrived from Sturmey USA. They asked for the old one back, and sent a pre-paid postage label. I despoked the wheel (arrrrrrgggg) and packed the failed hub up and sent it off. I have the new hub, a rim and 36 spokes on my workbench, and that's as far as I've got.

tcs
tcs is offline   Reply With Quote
Old 07-23-09, 05:29 PM   #31
Joako
Senior Member
 
Join Date: Jul 2008
Bikes:
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Did they take long to send you the replacement? I know it is too late, but isn't the shell the same, therefore swapping the internals would be easier? Or you were playing it safe in case the shell was the problem? Please keep us posted on this.
Joako is offline   Reply With Quote
Old 07-23-09, 08:11 PM   #32
tcs
Palmer
 
tcs's Avatar
 
Join Date: Mar 2007
Location: Parts unknown
Bikes:
Posts: 4,705
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Quote:
Originally Posted by Joako View Post
Did they take long to send you the replacement? I know it is too late, but isn't the shell the same, therefore swapping the internals would be easier? Or you were playing it safe in case the shell was the problem? Please keep us posted on this.
They (well, really, he) took three weeks to answer my email, but the hub got sent out just a day or two later.

AFAIK there are no instructions for (W) disassembly. Is it the same as the previous design? Probably. I don't have the 8-speed ball ring spanner, either (and yeah, I know there's a work around). Would Sturmey have still honored the warranty if I did a partial disassembly? Probably. Anyway, the wheel build was a real bodge job by a jackleg local wheelbuilder and I didn't mind the loss of it.

tcs
tcs is offline   Reply With Quote
Old 07-23-09, 09:29 PM   #33
Pocko
Senior Member
 
Join Date: Dec 2008
Location: Under the Downunder
Bikes: MTBs, BMX, Pocket MTB
Posts: 1,014
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Pardon for going "slightly" off topic, but it's still about SA IGHs. It's probably the best place for me to ask because it seems all the IGH gurus are already tuned in one place.

I'm new to IGHs and the only one I've had personal experience of is the SA 3 speed... and I'm slowly trying to get acquainted with others available - especially the SA 8 speed.

My question relates to the shifting method. The SA 3speed I have has a mini-chain screwed into a hollow axle and is pulled by a side cable to activate shifting (which I don't particularly like). But I've since read about another shifting method where a cam or lever rotates beside the cog? But I can't seem to get any more specific info about it.

Does any one know of a link that explains the details of an IGH that has this feature? The SA website has a few hubs like this but there's no tech sheet about them.

Has anyone tried these? Are they better than the usual central side chain-pull method? Thanks!

.
Pocko is offline   Reply With Quote
Old 07-24-09, 02:16 AM   #34
K6-III
Senior Member
 
Join Date: Jul 2003
Location: Brooklyn, NY
Bikes:
Posts: 1,453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The Sturmey 8 and 3-speed rotary series have the shift mechanism inboard of the chainstay.

All other sturmey's use indicator chains.
K6-III is offline   Reply With Quote
Old 07-24-09, 04:52 AM   #35
tcs
Palmer
 
tcs's Avatar
 
Join Date: Mar 2007
Location: Parts unknown
Bikes:
Posts: 4,705
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Sturmey Archer designed and patented the inboard shift cable in the early 1970s, but never put it in production. Shimano saw the idea for the good one it was and sat on the patent until it expired, then introduced their "revolutionary" seven speed hub with inboard rotary shift.

Sturmey's three speed series with inboard rotary shift has been cataloged for the last several years but such a hub has never been spotted in the wild. There are indications that the hub is finally "in the pipeline".

Of available three speeds, the SRAM iM3 is the only one to feature an inboard shift cable. With my Sturmey 8 out of service, I mounted an iM3 on the bike (a tikit) and I like this little hub better than the Sturmey SRF3 & AW, SRAM T3 and Shimano Nexus 3 hubs.

tcs
tcs is offline   Reply With Quote
Old 07-24-09, 09:56 AM   #36
rhm
multimodal commuter
 
rhm's Avatar
 
Join Date: Nov 2006
Location: NJ, NYC, LI
Bikes: 1940s Fothergill, 1959 Allegro Special, 1963? Claud Butler Olympic Sprint, Lambert 'Clubman', 1974 Fuji "the Ace", 1976 Holdsworth 650b conversion rando bike, 1983 Trek 720 tourer, 1984 Counterpoint Opus II, 1993 Basso Gap, 2010 Downtube 8h, and...
Posts: 15,818
Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 107 Post(s)
Quote:
Originally Posted by Joako View Post
Any updates on your replace [w] hub tcs? Is it a reliable hub?
I have about 600 miles on my new [w] hub and have had no problems.

Yet.

Quote:
Originally Posted by tcs View Post
... AFAIK there are no instructions for (W) disassembly. Is it the same as the previous design? Probably....
I suspect it's a pretty different design. The shift cable on the previous (non-W) pulled from the bottom, so (facing the hub from the right side) pulling the cable (to downshift) rotated the pulley counter-clockwise; the shift pulley on the newer (W) hub pulls from the top, so pulling the cable (to downshift) rotates the pulley clockwise. I'm not sure about the following, but I suspect it means a lot of the innards of the hub are different and some of them probably unscrew in the other direction from the earlier hub.

Since my new hub was provided and installed in a competent bike shop, I'm planning to have them do all service on it, at least until I'm quite sure the warranty is used up.

Last edited by rhm; 07-24-09 at 10:03 AM.
rhm is offline   Reply With Quote
Old 09-28-11, 03:39 AM   #37
pjkcycling
Newbie
 
Join Date: Sep 2011
Bikes:
Posts: 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Update, please?

Quote:
Originally Posted by tcs View Post
I'll try to keep the community updated over the next several months as I put more miles on this hub.
I'm grateful for your previous comments, and would be very interested in the offered update!

Cheers
pjkcycling is offline   Reply With Quote
Old 09-28-11, 06:05 AM   #38
tcs
Palmer
 
tcs's Avatar
 
Join Date: Mar 2007
Location: Parts unknown
Bikes:
Posts: 4,705
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
My 2nd XRK8(W) has about 1200 miles on it now. It shifts smooth and FWIW 'feels' very free running. I haven't touched the adjustment since the cable bedded in, haven't missed a shift, haven't found a neutral and like it quite a lot.
tcs is offline   Reply With Quote
Old 09-28-11, 08:21 AM   #39
JugglerDave
Senior Member
 
Join Date: Apr 2005
Location: Philadelphia PA
Bikes:
Posts: 467
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by tcs View Post
My 2nd XRK8(W) has about 1200 miles on it now. It shifts smooth and FWIW 'feels' very free running. I haven't touched the adjustment since the cable bedded in, haven't missed a shift, haven't found a neutral and like it quite a lot.
Likewise, 1800 miles on my 2nd XRF8(W). Zero problems, no adjustment, and works great.
JugglerDave is offline   Reply With Quote
Old 09-28-11, 09:00 AM   #40
badmother
Senior Member
 
badmother's Avatar
 
Join Date: Nov 2007
Bikes:
Posts: 3,247
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Anybody know a source in Europe that sell the SA 8speed hub w 28 holes? Want one for my Brompton. SJS only sell the 36 hole hub.
badmother is offline   Reply With Quote
Old 09-28-11, 10:02 AM   #41
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 20,358
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 633 Post(s)
Quote:
Anybody know a source in Europe that sell the SA 8speed hub w 28 holes? Want one for my Brompton. SJS only sell the 36 hole hub.
I believe that is all that is made..

AFAIK its only the 3 speeds made for Brompton that are 28 hole..
nothing but money to keep one from having the flanges plugged and re drilling a different hole pattern
in a Machine shop with aluminum welding and a drill press facility ..

a skip a hole pattern and a 24 spoke rim is another practical possibility,
people have used 36 hole rims and hubs in groups of 6, and had 2 radial and 4 crossing spokes

that idea, just leave out the radial spoke.
fietsbob is offline   Reply With Quote
Old 09-28-11, 10:08 AM   #42
tcs
Palmer
 
tcs's Avatar
 
Join Date: Mar 2007
Location: Parts unknown
Bikes:
Posts: 4,705
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Quote:
Originally Posted by fietsbob View Post
I believe that is all that is made..

AFAIK its only the 3 speeds made for Brompton that are 28 hole..
Biketoolsetc in the USA offers to retail customers the 28 hole XRF8(W) and a 28 hole AW. In the EU, Old Bike Trader says they have them.
HTH,
tcs

Last edited by tcs; 09-28-11 at 10:12 AM.
tcs is offline   Reply With Quote
Old 09-28-11, 10:27 AM   #43
kamtsa
Senior Member
 
kamtsa's Avatar
 
Join Date: Dec 2008
Bikes:
Posts: 1,815
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by badmother View Post
Anybody know a source in Europe that sell the SA 8speed hub w 28 holes? Want one for my Brompton. SJS only sell the 36 hole hub.
You can get a Brompton kit here http://www.kinetics.org.uk/html/8-speed.shtml
kamtsa is offline   Reply With Quote
Old 09-30-11, 06:25 AM   #44
social suicide
Senior Member
 
social suicide's Avatar
 
Join Date: Oct 2007
Location: Marquette
Bikes:
Posts: 678
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I've put close to 1000 miles on my R20 equiped with the XFR8-W. Only complaints are how noisy it is and the weight. 1800 gm! Been interested in the NuVinci 360 but where to put the extra cable?
social suicide is offline   Reply With Quote
Old 09-30-11, 11:50 AM   #45
badmother
Senior Member
 
badmother's Avatar
 
Join Date: Nov 2007
Bikes:
Posts: 3,247
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 60 Post(s)
Thank you, I`ll see what I can get. I wanted the hub, not the kit. I built a 20" 36/28 wheel w a Nexus7 some years ago but would like to avoid tracking down the different spokelenghts. I can see from the pictures on two different "kits" plus the SA homepage that the 28 hole one is being used.
badmother is offline   Reply With Quote
Old 10-04-11, 09:20 AM   #46
invisiblehand
Part-time epistemologist
 
invisiblehand's Avatar
 
Join Date: Jun 2005
Location: Washington, DC
Bikes: Jamis Nova, Bike Friday NWT, STRIDA, Austro Daimler Vent Noir, Haluzak Horizon, Salsa La Raza, Hollands Tourer, Bike Friday tikit
Posts: 5,586
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 27 Post(s)
Quote:
Originally Posted by badmother View Post
Thank you, I`ll see what I can get. I wanted the hub, not the kit. I built a 20" 36/28 wheel w a Nexus7 some years ago but would like to avoid tracking down the different spokelenghts. I can see from the pictures on two different "kits" plus the SA homepage that the 28 hole one is being used.
You can get short spokes from Dans Comp for excellent prices.
__________________
A narrative on bicycle driving.
invisiblehand is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 04:50 AM.