3T 9-32T Bailout Cassette for folding bike?
 

Does anyone have experience using a 3T 9-32T Bailout (or Overdrive) cassette with a folding bike? The gear range seems ideal for achieving a good range of gear inches with small wheels. While still expensive, prices on these cassettes are considerably cheaper than they once where.

If you're using one, what rear derailleur and shifter setup are you using? What chain ring and tire combination? How is the shifting? Any info appreciated.

https://bikerumor.com/2017/08/31/eb1...roach-1x-road/

On a 18" and 20" (406) bikes, I have used the 11-36t cassette and its been enough in most cases except for rather steep inclines with the bike loaded with touring gear.
This works on the more common Shimano 10speed (not 11sp being more common) freehub and Shimano XT or Saint/Zee shifter/RD.
I have seldom found any need for higher (ie. harder) gearing with the 52/11t combo (406 wheels) even with my weekly rides of the bike with folks on road bikes.
The max gearing is certainly enough to reel back most riders in a sustained effort over 5km or more, as most riders may get the initial jump with higher gearing but fewer can really sustain it for that long.

The 3T cassette you mention uses the XDR freehub and its not even common on 700c wheels (and certainly not available on smaller wheels ).
If you want this option, you will have to build the wheels with a XDR compatible hub.

The Bailout cassette is the more interesting one even for 700c wheeled bikes.
The jump in gearing from 9 - 19t is very gradual and makes more sense as the "muscle shock" jumping from 9t-11t is considerable for the Overdrive option, especially when pushing the pace in a group ride.

The XD freehub is not an issue as my Tern Verge X11 has one already. Its current cassette is a SRAM 10-42T, which gives plenty of range but the gaps between gears are huge, especially at the top end (10,12,14,16,18,21,24,28,32,36,42) where I spend most of my time, and it can be annoying at times. The Bailout cassette appears to address these top end gaps at the loss of the low end range (which I think I can live with) but I can't find anything on the net about its performance in the 9T sprocket and how it shifts. Its also unknown if the SRAM X1 X-Horizon long cage rear derailleur I have now would work well with the smaller cassette.

I actually had a Zee derailleur and 11-36T cassette on a Dahon Speed D8 and it worked very well. That bike is fitted with an Alfine 8 now though.

I have this 3T cassette on my titanium Birdy mounted on a Hope XDR road hub. But the XDR hub isn't necessary, this cassette fits on a XD hub too.

From factory, my Birdy had a 52-36 front and 11-28 rear. 52-11 is too short for a ETRTO 355 wheels bike.

I had to build a new wheel because the original hub cannot support XD or XDR (its freewheel body isn't exchangeable).

The 3T cassette works perfectly with the original 11s Shimano 105 derailleur and now also with an Ultegra 11s derailleur (both with long cage).

When I swapped the original wheel with the Shimano 11-28 cassette for the new one with the 3T cassette, I had almost no derailleur adjustment to do. I had only to increase the length of the chain to accommodate the bigger 32t sprocket.

With this cassette on a small wheel folder, the range of the cassette is almost big enough and I only seldom use the front 36t small chainring.

This kind of cassette is ideal for a fast small wheel folder, it avoids the big 60t front chainrings.

Yes, the 10-42t can be a pain for the 10-12-14 when riding with a fast group. (totally fine otherwise; I have it on my ChangeBike)
Too bad SRAM seems to have dropped the ball regarding 11sp XD cassettes and there is no racy 10,11,12,15,18,21,24,28,32,36,42 (or like) option.

If you want closer spacing, it's more convenient if you used double chainrings. Otherwise If you haven't exceeded the max single chainring size, you could build a custom 11-34 Miche 11 speed cassette by mixing your own cogs. You have to ask a dealer to do it. But that's only 309% range. The 9-32 would be 355%.

I have 12-34 with 44/24 double, which gives me 14-72.6 gear inches, 519%. I mixed my own Shimano 10 speed cogs, 12,13,14,15,17,19,21,24,28,34. It gives me closer spacing at the top and big spacing at the bottom.

the 9t cog will wear out very quick.

Indeed! My thoughts exactly. SRAM are you listening???

Generally speaking, I would agree. But in my specific case, my bike has a SRAM X-SYNC chainring that I want to keep, so I'm not considering the double chainring route.

Is that your assumption? Or do you have some actual data or experience to support the statement? Jipe I'd be interested to hear about your experience regarding wear on your Bailout cassette setup?

That's reassuring info! Looks like I'd be fine with my long cage SRAM RD.

I do not have this setup long enough (only since September 2019) to give a feedback about longevity of the 9t cog.

But with the wheel size and the chainring size I have, I do not use very often the 52-9 combination, only when riding quite fast.

Since the 10 smallest cogs are in steel do not think that wear of the 9t will be a problem.

The efficiency drops with cog size, particularly quickly at the small size end, if anyone cares, as the pull force from a chain link is more and more misaligned with the usable pull force for the next link. This ties to the wear as more and more work is done by the leading tooth that wears at an accelerated rate.

That makes sense. It would be interesting to know approximately by how much efficiency decreases / rate of wear increases as the cog size decreases. Do you know of any studies or research? It could be significant (or maybe not) in real world use.

Edit: I guess I'll find out for myself soon enough. I have a Bailout cassette winging its way to me as I type!

I definitely remember some a figure from some technical research paper. The pull force should drop like cosine of the angle between subsequent links. Links are always a bit loose, even on a new chain, so there is drop in force with which each subsequent link works. However, on small cogs, even with a new chain the cosine likely dominates. By Googling I found this paper: "Effects of Frictional Loss on Bicycle Chain Drive Efficiency", Spicer et al, J. Mech. Des. 123 (2001) 598, https://doi.org/10.1115/1.1412848. They looked for frictional losses, that they tried to model, lubrication and stuff, but found that in measurements the cog size mattered most, with difference between 15T and 11T being consistently at the level of (1-3)% efficiency. This paper seems different from the one I remember from the past, but it is a start.

Yes, there are many studies showing that the efficiency drops with smaller cogs.

But there are other factors like dirt that have also a major effect on chain transmission efficiency.

The same apply for wear: smaller cogs wear faster but also for wear, dirt has a bigger effect and it is well known that encapsulated chains last much much longer than chains exposed to dirt.

Now what does this mean in real world experience: as said for wear, I do not know yet. But for efficiency, honestly, I do not feel any difference between 9t or 10t and the classic 11t smallest cog (I also have two Moulton using the proprietary 10-28 Moulton cassette).

I am a big fan of the 3x9 Sturmey archer hub
about $130 in parts to build up but a good ratio option.
Not a hard build, competitive with the messing around with the other options.

I received the Bailout cassette, installed it on my bike and finally went for a 35km test ride this morning. The verdict - I love it! It runs more quietly / smoothly than the original SRAM 10-42 cassette. Even the 9T cog feels smooth. Shifting is better too. With a gear inch range of 32 to 115, its a bit over the top, and I was thinking about swapping out the chainring for something smaller, but I managed to get up the steepest hills without any problem during my test ride today, so I'll leave at is for now.

A tip for anyone thinking about trying this cassette > when setting up the bike, thinking that I didn't need the long chain used for the 10-42T cassette, I tried several shorter chain lengths, but shifting from 9T to 10T was mediocre. So I tried the long chain, and boom, problem solved. Shifting is perfect. The way my derailleur (all derailleurs?) works, progressively longer chains increase chain wrap so it seems that the smallest sprocket likes as much chain wrap as possible (and a properly set B screw) for good shifting. I might even try a longer chain sometime.

https://live.staticflickr.com/65535/...9da30b82_b.jpg

https://live.staticflickr.com/65535/...7ee5f7fd_b.jpg

With a Shimano Ultegra RD6800-GS or 105 RD5800-GS derailleur, the minimum chain length work fine with the 3T Bailout cassette.

I was forced to keep the chain the shortest possible because I have also a front 52-36 compact and the derailleur must be able to compensate for the big difference in number of teeth, 23 rear + 16 front = 39t, which is actually more than what Shimano specifies for those derailleur (max = 37t) but it works.

But I must say that I use the font 36t chainring very seldom, the 9-32 range of the 3T Bailout and the 52t chainring are sufficient for most cases with ETRTO 349 wheels.

Interesting to read that, Jipe! Maybe my chain length issue is something specific to SRAM long cage derailleurs meant to work with 42T cogs.

For Shimano derailleurs, only two links extra are needed on top of the big-to-big cog chain length, whereas SRAM recommends four links.

With the 52T chainring and 32T cog at the back, that worked out to 114 links. I tried 112 link and 114 link chains I had laying around, and both worked ok other than poor shifting from 9T to 10T. I put the 118 link chain back on, and it works like a charm.

Edit:

> Maybe my chain length issue is something specific to SRAM long cage derailleurs meant to work with 42T cogs.

↑ Yup, after a little more digging I'm fairly certain this is the reason. Both the Shimano Ultegra RD6800-GS and 105 RD5800-GS derailleurs Jipe has used/is using are designed for a maximum cog size of 32T, which the Bailout cassette has, so there should no issues with setting up those derailleurs normally.

However, my SRAM X1 X-Horizon long cage rear derailleur is designed for a maximum cog size of 42T whereas the maximum cog size of 32T on Bailout cassette is considerably smaller (same size as 3rd gear on the SRAM 10-42 cassette I was running). The solution to my shifting problem was to set up the derailleur normally for the 42T cog then effectively "never use" any gears below the 32T "3rd gear".

Hill bail out would be a double crank really small granny gear..

Let me guess ... you didn't bother opening the link in my first post above? actually, did you read anything other than the word "bailout" :foo:

Kabuto How are you liking the bailout? I had the same problem with too wide of gear steps on my Pacific Reach GT folder/minivelo, which had the exact same drivetrain as your Tern, but I went with a Force AXS 10-42 upgrade. I’m running a 52T Wolf Tooth chainring in front. However, I’m now concerned about trashing my new Force AXS levers quickly, as I take this bike in and out of a storage bin at my marina all the time. Now, I’m thinking I’ll transfer my all road bike’s old Red Etap 11-speed levers and derailleur over to the Reach GT and use a Bailout cassette. I live in Chicago and won’t travel with this minivelo, so I don’t need climbing gears.

I looooove it. Shifting is noticeably smoother with the Bailout cassette than the original SRAM 10-42. I still use the SRAM 10-42 cassette for loaded touring, for the lower gears, but for everything else the Bailout cassette has been absolutely perfect. I run it with a WolfTooth 48 tooth chainring up front, which gives me a gear inch range of about 30 to 107. That's been perfect for my needs. I rarely use the 9 tooth sprocket up back but I looooooove the one tooth steps between the 10-11-12-13 tooth sprockets.

Thanks! I think you've convinced me. My Force AXS cassette has the 1 tooth steps down low, but it would be nice to have that 9 tooth as well, as I'm a powerful rider (and it is really, really flat in Chicago). ;) Allows me to swap the Force AXS over to my all road bike, which I'll set up 1x. Now that will be a new adventure deciding which chainring to go with for that one!

I have this cassette on my Birdy titanium now with 20" wheels and a FSA SL-K Light 52-36 front.

The rear derailleur is a Shimano Ultegra medium cage.

It works perfectly, as well as with the original 11-28 Shimano cassette.

The only thing I had to do when switching from the original Shimano 11-28 to the 3T 9-32 was increasing the chain length (and of course making a new wheel with a XDR hub).