Three-speed fixed: They live!

[andygates]

Sunrace Sturmey Archer News: S3X Fixed Gear 3 Speed

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.

[Che]

I remember Sheldon discussing the possibility of these reemerging. Had sort of given up.

[Chris S]

I love the comment suggesting naming it after the mighty Sheldon. SB3X? Yup - I'd buy one.

[Che]

Someone proposed one with a disc mount. That'd be teriffic if one fancied putting it on a 3-speed fixie tandem!

[border-rider]

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.

[clarion]

OK.  I want one.

[Polar Bear]

Next?  Rohloff 14 speed fixed...

[rogerzilla]

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.

[mike]

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...

[mike]

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.

[Adrian]

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

[border-rider]

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.

[andygates]

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. 

[rogerzilla]

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)

[border-rider]

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

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

[Frenchie]

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.

[rogerzilla]

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.

[border-rider]

Alternatively, the losses are 4 times those of a fixed transmission

[rogerzilla]

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 

[andygates]

I just hope they pitch it at an accessible "clubman" kind of price, and not up in the Rohlosphere. 

[rogerzilla]

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.

[border-rider]

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

enough to make a noticeable difference on the hills

[rogerzilla]

I made it 0.4mph on the flat, or about the same as switching on a hub dynamo.

[bobajobrob]

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".

[clarion]

It's hte reason I didn't get a fixie in Calderdale...