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-   -   building a s3x into a folding bike (http://www.bikeforums.net/folding-bikes/936624-building-s3x-into-folding-bike.html)

adlai 03-03-14 10:02 PM

building a s3x into a folding bike
 
One idea that has intrigued me recently is the idea of putting a Sturmey Archer s3x into a folding bike like a Montague Boston. I'd actually probably use a flywheel with it since the goal would be versatility. The s3x looks like it's a bit more durable than other IGH hubs too.

Thinking about it, the only problem I can think of is that during folding, the cable tension to the hub in the rear wheel might be interrupted, which would ruin the hub setup. Of course, the Boston 8 exists, which uses an 8 speed internal hub. In my imagining of the bike, I'd use bullhorns which would fold down during transport...

So, is that a problem?

downtube 03-03-14 10:26 PM

why not an SA 8sp? I think new IGH are very durable....and efficient.

Om,
Yan

fietsbob 03-03-14 10:45 PM

S3X + Freewheel? why not an S-A 5 speed .. S3X is the bottom 3 ratios of the 5 speed anyhow.

adlai 03-04-14 12:05 AM

Quote:

Originally Posted by fietsbob (Post 16546205)
S3X + Freewheel? why not an S-A 5 speed .. S3X is the bottom 3 ratios of the 5 speed anyhow.

relative simplicity and weight.

fietsbob 03-04-14 12:26 AM

You Got weight data to quote? the 3 planetary gears are there , just the inverse is not used.

3 speed s simpler the justification ?
AW3 has had a history going back to the 30's , and now is aluminum hub-shelled too ..

.. some in 28 spoke hub shells .. made for smaller wheels ..

adlai 03-04-14 10:55 AM

I've run small wheeled folding bikes before.

Didn't like them one bit. It just feels so unstable.

And yes, I've also run a SA8 before too. It didn't feel very efficient either.

mconlonx 03-04-14 01:03 PM

Quote:

Originally Posted by adlai (Post 16546110)
One idea that has intrigued me recently is the idea of putting a Sturmey Archer s3x into a folding bike like a Montague Boston. I'd actually probably use a flywheel with it since the goal would be versatility. The s3x looks like it's a bit more durable than other IGH hubs too.

Thinking about it, the only problem I can think of is that during folding, the cable tension to the hub in the rear wheel might be interrupted, which would ruin the hub setup. Of course, the Boston 8 exists, which uses an 8 speed internal hub. In my imagining of the bike, I'd use bullhorns which would fold down during transport...

So, is that a problem?

If they don't have issues with the 8sp IGH version, why would you have issues with an S3X build, assuming you run housing similar to their stock 8sp model? You may run into issues if you get the single-speed frame and it doesn't have the integrated cable stops of the 8sp frame. But still, once the bike is assembled, cable tension should snap back to where it's supposed to be...

Do some research on the type of freewheel you need for the S3X as well -- I've only used them fixed, but I know there are specific brands or configurations of freewheel you need to make it work for this hub.

fietsbob 03-04-14 01:19 PM

some S3X equipped bikes have passed thru the LBS. the tips of the splines are threaded ..

Rob_E 03-04-14 01:25 PM

Wouldn't it be easier/simpler/lighter to use the non-fixed SA 3 speed without the freewheel?

As far as cable tension goes, it's something you might have to keep an eye on, but it's easy to adjust and, as has been said, theoretically any changes to cable tension are undone when you unfold the bike, so just don't try and ride it when it's folded. Many folding bikes come with IGHs, so i must not present a huge issue. I had a bike that split in two, and this issue was solved by mounting the shifter to the seat tube, so the front half of the bike could be removed without messing with the shift assembly.

For simplicity, I have always been tempted to go with a two speed hub. There's one model that shifts automatically based on the speed you're traveling, and one that shifts with a brief back pedal. No shift lines required.

I have never done it, though, because I like more gears.

bhkyte 03-08-14 07:31 AM

Personally I would go for dualdrive which would be compatable with brifters and be reliable.

darukhan 03-08-14 10:15 AM

This is an interesting thread to me, because I've been considering removing my dual drive hub to replace it with an S3X hub on my Birdy bike.

Over the past year, I've found that I'm mostly changing between three gears during my commute, and that's using the internal gears, not the 8 speed cassette! Also, I've been intrigued with the idea of riding fixed, since I'm usually pedalling the entire route during my commute anyways. So I figure the best hub to try would be the S3X.

Adlai... the part that I really don't understand about this thread is why you are considering putting a freewheel on a fixed gear hub?

As Rob_E mentioned already, why not just get a different model S-A 3 speed internally geared hub that's NOT fixed?

mconlonx 03-08-14 03:09 PM

Quote:

Originally Posted by darukhan (Post 16559969)
Adlai... the part that I really don't understand about this thread is why you are considering putting a freewheel on a fixed gear hub?

As Rob_E mentioned already, why not just get a different model S-A 3 speed internally geared hub that's NOT fixed?

S3X has a closer gear ratio and direct drive is at the top, not in the middle. How that figures into OP's decision to go that route, I don't know...

S3X
• Overall Range - 160%
• Gear 1 - 62.5% (-)37.5%
• Gear 2 - 75% (-)25% (Gear 1 + 20%)
• Gear 3 - 100% Direct Drive (Gear 2 + 33%)

AWC
• Overall Range - 177%
• Gear 1 - 75% (-)25%
• Gear 2 - 100% Direct Drive (Gear 1 + 33%)
• Gear 3 - 133% (+)33.3% (Gear 2 + 33%)

darukhan 03-08-14 03:16 PM

Quote:

Originally Posted by mconlonx (Post 16560538)
S3X has a closer gear ratio and direct drive is at the top, not in the middle. How that figures into OP's decision to go that route, I don't know...

S3X
• Overall Range - 160%
• Gear 1 - 62.5% (-)37.5%
• Gear 2 - 75% (-)25% (Gear 1 + 20%)
• Gear 3 - 100% Direct Drive (Gear 2 + 33%)

AWC
• Overall Range - 177%
• Gear 1 - 75% (-)25%
• Gear 2 - 100% Direct Drive (Gear 1 + 33%)
• Gear 3 - 133% (+)33.3% (Gear 2 + 33%)

Very good point about the gear range and direct drive placement.

fietsbob 03-08-14 03:21 PM

Sachs -Sram 3 speed is just a hair lower and higher than S-A.. for 1st and 3rd
.73 vs .75 and 1.36 vs 1.33


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