Yet Another Cycling Forum
General Category => Freewheeling => Velo Fixe => Topic started by: andygates on 04 September, 2008, 02:27:30 pm
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Sunrace Sturmey Archer News: S3X Fixed Gear 3 Speed (http://sunrace-sturmeyarcher.blogspot.com/2008/09/s3x-fixed-gear-3-speed.html)
S3X Fixed Gear 3 Speed
So I know there are many of you out there that are very interested in the little bit of info I recently got my paws on.
The first batch of prototype Fixed Gear 3 speeds is finished. The new hub will be called the S3X. The hub will be made using a much stronger aluminum hubshell. Overall gear range will be 160%.
* 1st Gear -37.5%
* 2nd Gear - -25%
* 3rd Gear - Direct Drive
* Gear step gear 1 to gear 2: 20%
* Gear step gear two to gear 3: 33%
Shifters are still up in the air but we have had many requests for a bar end style shifter. Also we are still planning on the possibility of doing some anodized colors with laser etching instead of screen printed graphics. Please comment on what you would like to see in the way of shifters or color choices.
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I remember Sheldon discussing the possibility of these reemerging. Had sort of given up.
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I love the comment suggesting naming it after the mighty Sheldon. SB3X? Yup - I'd buy one.
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Someone proposed one with a disc mount. That'd be teriffic if one fancied putting it on a 3-speed fixie tandem!
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Whatever will they think of next ?
If they could find a way to let you stop pedalling when you are moving - like when you go down steep hills - it would be nearly perfect.
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OK. I want one.
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Next? Rohloff 14 speed fixed...
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Here's a little secret.
The ASC wasn't very good.
There was a lot of slop due to the drive being transmitted through pawls (like any SA hub) and it was nothing like a normal fixie. It had one use: for hilly time trials. For the full fixed experience, you'd need a totally different design, and I suspect this is a reworked ASC.
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what's the point?
Most hills can be struggled up on 65-70" fixed, the only time I regret being on't cog is when I'm faced with a long fast downhill and could do with a few more inches (fnaar). This would make uphills slower and would be no use at all on the way down...
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replying to my own stupid post - Mike, you muppet, you'd build it with 90" gear, then have access to 70ish for normal, 55 for uphill and 90 for downhill.
Idiot.
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replying to my own stupid post - Mike, you muppet, you'd build it with 90" gear, then have access to 70ish for normal, 55 for uphill and 90 for downhill.
Idiot.
No need to be so harsh on yourself
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No need to be so harsh on yourself
Indeed not.
The problem is that direct drive is third - which as you say would be the big gear. So most of the time you'd be riding a much-less efficient gear
Plus, having the usual drive gear in the middle adds immensely to the likelihood of experiencing that great SA gearslip, and a nads/crossbar or face/road interface.
As RZ said, the originals were crap.
My experience of using SA hub gears was that they are so inefficient and sloppy in the lower ratios that it was faster and easier to ride on proper fixed.
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Well, SA have been saying all along that what has been stalling development is getting the balance right between a smooth quick change and no slop. Modern riders, they rightly presume, are much less tolerant of slop than the oldies were.
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Replying to Mal - I expect they'll use a NIG (no intermediate gear) design like the current AW and SRF-3, and I'm not actually sure the ASC had a "neutral" anyway.
The NIG design uses an extra set of pawls in the driver which are disabled by one end of the (much modified) clutch rotating a metal shroud and flattening the pawls against the driver body. I've taken both old and new types apart.
(and yes, they worked again afterwards)
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I think the ASC had an "intermediate neutral" between gears. A couple of the old boys in Leeds CTC told tales of descending apace with the trigger carefully positioned :o
Hell of a mess if it went wrong.
My ideal fixed hub gear would be simple 2-speed design with no neutral, and no lossy planet gears, shiftable only when stationary. Ratios maybe 70 and 60". With the 70 as direct drive, and no backlash. Like a TF
That would be just like turning the wheel round, but easier
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My ideal fixed hub gear would be simple 2-speed design with no neutral, and no lossy planet gears, shiftable only when stationary. Ratios maybe 70 and 60". With the 70 as direct drive, and no backlash. Like a TF
That would be just like turning the wheel round, but easier
Yes.
72'' and 81'' for me please.
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Apparently a 3-speed Sturmey isn't really very lossy provided it's run-in and oiled (92% efficient, and a derailleur setup with its two jockey wheels is probably about 95% - only a singlespeed or fixed with a clean chain makes the magic 98%). The 5-speed, on the other hand, was really bad in the lowest gear, to the extent that you might as well push on in second.
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Alternatively, the losses are 4 times those of a fixed transmission ;)
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Alternatively, the losses are 4 times those of a fixed transmission ;)
True, but assuming a power input of 200W, work out how much faster you go for an output of 196W versus 184W ;)
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I just hope they pitch it at an accessible "clubman" kind of price, and not up in the Rohlosphere.
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Generally their stuff is cheap. An S-RF3 is just as hard to make and can be had for £40 if you shop around.
If you can't wait, the highly useful Derek at oldbiketrader.co.uk has just got an ASC in for £180. Knowing him, it will be a good 'un. Like most old Sturmey hubs, it has a 5 3/4" axle so you'll need 110 spacing at the rear.
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Alternatively, the losses are 4 times those of a fixed transmission ;)
True, but assuming a power input of 200W, work out how much faster you go for an output of 196W versus 184W ;)
'bout 6%
Bicycle efficiency and power -- or, why bikes have gears (http://users.frii.com/katana/biketext.html)
enough to make a noticeable difference on the hills
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I made it 0.4mph on the flat, or about the same as switching on a hub dynamo.
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I'm interested.
The problem is that direct drive is third - which as you say would be the big gear. So most of the time you'd be riding a much-less efficient gear
Surely the idea is to have 3rd set up as your normal gear and use the other two on hills. Could be useful on hilly rides. The gearing is the only thing that stops me taking the fixed out in the hills round here, as they tend to be steep in places and I can't get up them with a 70" gear. This hub would give gears of 44", 53" and 70".
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It's hte reason I didn't get a fixie in Calderdale...
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Wouldn't be any good for our "10" course (U48) - it's flat except for the first half mile, which is gently downhill (Jaded knows it now, after last night's dogging ;)).
For that, you want something like 84" direct drive, with 90" for the very start. With the ASC, you'd be condemning yourself to using the planetary geartrain for 96% of the time, and half a mile an hour in a time trial is a really big time difference.
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Rohlosphere...
I think that one may be a candidate for the 2010 edition of the Oxford Dictionary... :D
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My ideal fixed hub gear would be simple 2-speed design with no neutral, and no lossy planet gears, shiftable only when stationary. Ratios maybe 70 and 60". With the 70 as direct drive, and no backlash. Like a TF
That would be just like turning the wheel round, but easier
Yes.
72'' and 81'' for me please.
The more I think about it, the more the Dingle (http://www.surlybikes.com/new/dinlgecog_pop.html) makes sense. 40/19 and 42/17 for 57" and 67".
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The more I think about it, the more the Dingle (http://www.surlybikes.com/new/dinlgecog_pop.html) makes sense. 40/19 and 42/17 for 57" and 67".
The trouble with that set up is that, whilst it works fine for two singlespeed gears, if the chain is to be taut enough for fixed the wheel would stil have to come out and be re-set each time you wanted to change the ratio.
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It's less hassle than flipping the wheel though, right? And less to worry about than a fixed hub gear.
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I just hope they pitch it at an accessible "clubman" kind of price, and not up in the Rohlosphere.
Did I mention that I held one at The Cycle Show? (http://yacf.co.uk/forum/index.php?topic=7149.msg165305#msg165305) They were talking about the same sort of price as a "normal" 3 speed, ie around £90 including shifter, of which they anticipated a choice.
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The bad news is that any 3-speed weighs as much as a triple derailleur setup (that nice alloy case is almost full of case-hardened steel), so you have to look at the other advantages.
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The more I think about it, the more the Dingle (http://www.surlybikes.com/new/dinlgecog_pop.html) makes sense. 40/19 and 42/17 for 57" and 67".
This set up from Londonfixie (http://www.londonfixiebike.co.uk/dualcog.html) has an advantage over the Dingle in that you can chose from a wider range of cogs
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A Dingle is simple & neat. And I like the idea of the LF one above, but not sure about the spacing of the cogs...
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Yep, that's what I thought. Lots of force on those screws.
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Should not be a problem, motorbike rear sprockets are attached in that way.
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Using screws to attach a single sprocket should be fine, but it's the unsupported length of the screws when used to attach two sprockets that trouble me. I can see bent bolts when you hoy it up a hill...
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Thats a fair comment, unlike a motorbike sprocket carrier the hub was designed to carry a disc which I would expect to have a lower torque loading than a sprocket under load. Maybe the hub housing would / should fail first?
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The LeVeL system works like that - with bolts to hold the sprocket on - but the hub has bosses that stick out and its these that take the force
But I guess most disc hubs are pretty robust...I think I'd agree that bending the bolts is a bigger risk.
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With the bolt-on double I'd assume safety depends on the quality of the bolts and the spacer. The load is after all shared over six equally spaced points. To be fair, the LF comments are suitably qualified: "be it on your own responsibilty" I think.
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The bad news is that any 3-speed weighs as much as a triple derailleur setup (that nice alloy case is almost full of case-hardened steel), so you have to look at the other advantages.
How about "someone has to get one just so we can find out why they fell out of favour in the first place."
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I gotta get one!
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We have a volunteer
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A volunteer who is short of resources right now, but I'll review when the hubbly lovelies hit the market. ;)
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I quite fancy one too. I enjoy riding fixed but I live on the edge of the Wolds , big hills one way flat the other way, would certailny save messing about changing cogs.
The novelty value would be attractive too ;D
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The bad news is that any 3-speed weighs as much as a triple derailleur setup (that nice alloy case is almost full of case-hardened steel), so you have to look at the other advantages.
How about "someone has to get one just so we can find out why they fell out of favour in the first place."
I'd like to try one, but not to own one. The gear jumps are too large for TTing and "normal" is the top gear when I'd like it to be the middle. It's probably best for someone who really loves riding fixed and just wants a bit of help uphill - but experienced fixed riders will usually tell you the downhills are the problem. You certainly want to spend 95% of your time in the "normal" gear for efficiency.
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You're right about all of that, of course, but I imagine that to have normal in the middle, which I would definitely prefer, would mean lots more geary-type bits inside.
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The bad news is that any 3-speed weighs as much as a triple derailleur setup (that nice alloy case is almost full of case-hardened steel), so you have to look at the other advantages.
How about "someone has to get one just so we can find out why they fell out of favour in the first place."
Could run a raffle? "X" quid a ticket - winner has to install and test it? Anyone know/guestimate the price?
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About 90 quid, I'd guess.
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And a tenner to get "Sheldon is my co-pilot" engraved on the shell before building it. :thumbsup:
A project for when I'm out of this Northern Rock mortgage ;)
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"About 90 quid, I'd guess."
Well, I'll put a tenner in a pot if nine others will - winner gets the hub! On condition that installs and tests within 12 weeks!
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Make it a fiver and I'm in.
Mind you, if it's built into a 700c wheel with 120mm spacing, lots of people could try it out. Just need the SA top tube clip-on fulcrum and guide pulley to fit it onto any fixie or 5-speed bike.
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So to resurrect this topic, any got one or know anyone who has got one?
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There's a thread on the CTC forum - they're not in the UK yet, but Derek at Old Bike Trader has ordered 10 of them from SA. I think he'll be surprised how fast they disappear.
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Want one!!!!!
Haven't got a bike it'll fit (yet). But I really do want one!!!
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IF less than a 100 quid and IF I can source one, then I'll get one (I'm really missing fixed after 4 months, with "variable" I'd start again!). But I rather suspect price will be nearer 2 than 1 ton.
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I don't see why it would cost more to make than an S-RF3 (£40 if you look in the right place), so they're milking it if it's £200.
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I don't see why it would cost more to make than an S-RF3 (£40 if you look in the right place), so they're milking it if it's £200.
Hype? Supply less than demand?
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Development cost, specialised parts and their associated tooling and much smaller production figures would all justify a larger per unit cost.
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Our senior club member's recollections of the slackness of the original hub, so that it was always as if the chain was slack, and the ability to find a false neutral between the gears, would put me off the idea. Will the new one be better made?
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Development cost, specialised parts and their associated tooling and much smaller production figures would all justify a larger per unit cost.
Maybe. But a new AR (a complicated dual-epicyclic hub sold in tiny numbers to time triallists) used to cost only about 20% more than the simple AW introduced shortly afterwards, which is probably not much more than the extra it cost to make. I don't have a comparative cost for the ASC, because that was introduced about 10 years later, with a war in between.
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...a new AR (a complicated dual-epicyclic hub sold in tiny numbers to time triallists) used to cost only about 20% more than the simple AW introduced shortly afterwards...
There's the reason why the original Sturmey went bust. Brooks was part of the same company, and look what's happened to their pricing.
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I think the UK/US fashion for derailleurs, which deliver far more speeds with barely any efficiency loss*, was the problem. MTB was the other - SA couldn't deliver the kind of gear range required.
Technically Sturmey didn't go bust - they were the victim of a highly leveraged buyout by Lenark which went wrong. The Taiwanese have done a pretty good job with the brand (and designs) so far.
*generally, hub gears with lots of speeds are pretty inefficient; the SRAM 7 speed is quite clever as it only ever uses one planetary geartrain (three suns, three-stage compound planets, one gear ring), but some of them use three planetary stages in series, and each one saps 3-5% of power.
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We've just had an ASC donated.
Gonna bung it on ebay :)
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Do you have the shifter?
I'm not interested, by the way.
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It's not on there yet. :(
Not that I'm interested, either... ;)
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Yes, we do have the shifter.
Not that you are interested ;)
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Oh good. I mean, for whoever might want it, that is. But it's still not on there...
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I'd rather have an AC (non fixed, ultra-close ratio) than an ASC The ASC has top gear as direct drive (like the new S3X) which wouldn't suit what I'd want to do with it.
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Oh good. I mean, for whoever might want it, that is. But it's still not on there...
No, we won't list it for a few week because we want to try it first.
I'll mention on here that we're listing so you can not bother to keep an eye on it ;)
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Whatever will they think of next ?
If they could find a way to let you stop pedalling when you are moving - like when you go down steep hills - it would be nearly perfect.
;D :thumbsup:
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Rohlosphere...
I think that one may be a candidate for the 2010 edition of the Oxford Dictionary... :D
+1
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We've just had an ASC donated.
Gonna bung it on ebay :)
We have one as well, we had a bloke track us down all the way from Switzerland but the sale fell through when someone who shall remain nameless did not bother to post it on time. >:(