nz6666

My current folding bike got a 11-28 T 9 speed cassette together with a single 56 T chain ring. My bike is a 20 inch (406) folding bike. The gear ratio is a little bit too big for the hills around here (many 8% - 10%, some 15%).I constantly use 28 T cog but still feel too hard. So I am thinking changing the cassette to something like 11-34 or 36 T if possible. I am also planning to do some bicycle tour with this bike (yes with this folder) so would like something more capable.

The rear shifter on my bike is Shimano Alivio M4000 9 Speed shifter. The rear derailleur is Shimano sora 3500 short cage.

I found these after a quick Google. There are 11-32/34 options or even 12-36, not sure if my existing components can take any or all of these? I would like keep as many existing components as possible and also use the most economic option if possible. I know I will probably need to change the chain, which is ok. Or if there is any other option? I know I can change crank set to something like 39/53 but don't like the added complexity.

Shimano Deore HG61 9 Speed MTB Cassette

Shimano XT M770 9 Speed MTB Cassette

Shimano CS-HG50 9 Speed Cassette

Shimano HG80 9 Speed Cassette

hueyhoolihan

i would look into a chainring with fewer teeth. like maybe 39-40T. unless your crank has a BCD greater than 130, it's doable. if touring i would go lower, possibly a 34t chainring, 11-28 cassette, which may necessitate a new crank.

SkyDog75

The Sora 3500 short cage rear derailleur's specs list a 32-tooth maximum cog. You might be able to make a 34 work.

I don't suppose changing to a smaller chainring on your crankset is an option? That way, you'd only have one thing to change instead of possibly having to change your cassette and derailleur.

nz6666

I want to extend the capability for the hills on current setup but still keep the the existing 56 t chainring for the flat. I saw the spec now, seems like I the 32t option (not sure if 34t will do) is my best bet.

hueyhoolihan

i rarely question what the performance capabilities are of people on the forum, but you do realize that (according to the gear inch calculator i use,) with a 20" wheel, 32mm tire, 56 tooth chainring, 11 tooth cog, and a (reasonable) 80 rpm cadence you'll be traveling at about 25 MPH? the recent world hour record was set at an average of about 32.3 MPH. just letting you know.

HillRider

Remember this bike has 20" wheels so a 56x11 is only 102 gear-inches. Not abnormally high.

sanmi

I agree that a smaller chain ring is the cheapest option in your situation, unless you really need the 56/11 combo with your 20" wheels.

I had a similar problem on a bike used for commuting where I wanted close gear spacing, but that I also used for loaded touring in hilly areas. I made a custom cassette combining a 13-23 and a 11-32, which got me 13-14-15-16-17-19-21-23-32. The jump from 23-32 is huge, but perfect for my needs. Not the cheapest option though and you would likely need a medium cage derailleur. Won't know for sure until you try.

Good luck.

hueyhoolihan

don't forget the tire profile, i guessed 32mm.

anyway, here's the calculator i used. see what you get. i came up with about 114 GI, maybe i screwed up somewhere, wouldn't be the first time (today )... if so i apologize and stand corrected.

HillRider

I just based it on a nominal 20" wheel OD so the calculation was 56x20/11 = 101.8 gear-inches

For better accuracy, in reality there are two "20"" wheels used on folding bikes, ISO 406 and ISO 451. Assuming 32 mm tires on either of these the actual outside diameters and high gear gear inches would be:

For ISO 406 rims: 406+(32x2) = 470 mm = 18.5" OD and the high gear would be 18.5x56/11 = 94.2 gear-inches

For ISO 451 rims: 451+(32x2) = 515 mm = 20.3" OD and the high gear would be 20.3x56/11 = 103.3 gear-inches.

MisterK

9 speed I'd just go with a 11-32t deore cassette. Would give you the lowest tooth and the highest tooth your Rd can handle. I'm not a huge fan of a 52t chaining on the crank. I really think, if you deem feasible atleast, it would be beneficial to change to a 42t chairing on the crank

HillRider

One more time; this bike has 20" wheels. A large chainring is needed to get any reasonable top gear. Actually the OP would be better off with a double crank, say a 56/42 combination instead of a deeper cassette but that may not be an option

nz6666

Yes 11 - 56 is very hard even on flat. But I use it on some downhills (normally in weekends when there is little traffic). Or there were couple of times when I just wanted to compete with some big bikes (it's fun to pass a team of road bikes ) at least for a while. Anyway I want to keep that potential.

nz6666

Thanks for the inputs. I may change to a 11-32 for now. For loaded tour I may change it to a smaller chainring or a double chainring (it's doable on my bike).

nz6666

Ok the most important thing, of the list which one should I get for a 11-32 T? I don't need very high end product just something reliable is good enough.
And all of them say 'For Super Narrow 9-speed HG chains', what does it mean?

Bill Kapaun

"Generic" 9 speed chain will work. It's thinner than 8, 7>>>>

I'd just get the Shimano compatible cheapest cassette for now and see if the gearing works for you.

Bezalel

I don't see an economical solution for touring. Generally for touring you'd want a gear inch range of about 20-100, no single cassette would give you that range. Going to a double (or triple) will necessitate losing the 56t chain ring and the high end. Shimano's solution for this is the Capreo cassette which has a 9-tooth small cog but it requires a Capreo hub.

Is the frame even capable of handling a front derailleur? If it doesn't have a derailleur tab look at the seattube chainstay angle it should be between 60-66 degrees and the seattube diameter should be 28.6, 31.8, or 34.9mm

Just going with a wider cassette will also lower the tension pulley of your RD. I'm not sure when ground clearance becomes an issue.

nfmisso

IF there is room, I suggest changing to a Shimano M592 RD, and a 12-36 cassette. You will need a new chain. This will reduce your top gear by 9%, and give you 24% lower at the bottom.

For touring, if you can change to a double crank, it would be very beneficial. I would suggest leaving your big ring in its current location, and put a smaller ring towards the inside, where you can only use it with the 4 or 5 largest cogs at the back. I would suggest the smaller ring be in range of 40 to 44T and only be used as granny bailout gear.

nz6666

Thanks, I finally settle on this solution.

nfmisso

Please give us an update after you have a few hundred kilometers/miles on the combination to let us know how you like it.
Thank you

nz6666

Sure.

kimpw

I ride a 38/26 with 11-34 cassette on my tourer/bike camping bike. I ride about 3 miles of constant uphill, some steep stretches about %15. I've never switched to the small ring. I've also used 1x9 36 front and 12-36 cassette. I've never had trouble with either configuration.

I've found that 34 is plenty. Most of the hills I'm on the 32, and the 34 helps for the extra steep hills, without having to shift down on the big ring.

nfmisso

What size tires? You only describe the chain drive section of the overall transmission, tire size is critical for the overall picture. The OP has ETRTO 406 rims. His 56T is equivalent to a 36T on a ETRTO 622 rim with the same cross section tire.

kimpw

Sorry, my tire size was 584. 26x2.00 tires. 38/34 gives me about 28 gear inches, but for touring I like to be able to have around 19-20 gear inches, which is is why I have a 26t granny.

TBH 56t front ring is pretty high. With a 34 cassette your lowest gear inch will be around 30-31 gear inches (assuming you have 1.75 tires). Even with a 36 cassette it will be around 29-30 gear inches.

I would change the front ring to something more manageable. 46t front with 12-36 will give you about 71 gear inches top speed and 24 gear inches bottom.

hueyhoolihan

to simplify matters i don't really consider anything above 70 gear inches necessary for any type of loaded touring.

fietsbob

95GI for strong tailwinds 700c wheels 14:50t [ I have 80GI for my Folding bike's High.. ]