dwr1961

Anyone know where I can find this? I need a Shimano-compatible cassette for my buddy who has converted his old MTB for road use... Right now his smallest cog is a 13 and he easily spins out at moderate velocity...

Thanks for your ideas.

HillRider

The best I found was A. E. Bike who lists Shimano 7-speed cassettes in 11x28 and 12x21 format.

Look here:

https://aebike.com/page.cfm?PageID=30...nsearch=Search

Bill Kapaun

The only "close ratio" 7 speed I see with an 11T top cog is an 11-19. Shimano "L"
Next is 11-24. SHimano "ai".

I thought I was spinning out too much on a 13, so I went to a 12. It turned out I wasn't spinning out nearly as much as I thought and went back to the 13 and worked on my cadence.
IF you have a wheel with a 12 you can swap in, I'd recommend trying that first.

What's his largest chain ring size?

dwr1961

Therin lies the heart of the problem: He's got a crankset with 42/32/22 chainrings. It was a replacement many years ago for the bike's OEM setup... The bike itself is a Trek 850 (circa 1991). Currently he rides it exclusively on the road each morning for a 30-60 min. solo "fitness ride" around his neighborhood. The terrain's relatively flat, so he averages aroiund 20mph (he's in pretty good shape). Spins out on the downhill portions and basically lives on the big ring / small cog combo.

I've seen the 12/28's, but I think an 11-21 would be ideal for his situation - since he's essentially time-trialing on his old rigid-fork MTB. I noted that a couple of UK vendors had this type of cassette in stock, but I'm hesitant about purchasing internationally (mostly because I've never done it).

Of course he COULD replace his crank or chainrings, but the cassette option is cheaper and easier.

Gonzo Bob

I had a similar experience. I built a pair of "road" wheels for commuting on my MTB. My tall gear was 42/13 which worked out to about 80" which I found myself spinning out on downhills or with tailwinds. I ended up changing the cassette to one that started with a 12 (the smallest I could go on my old Uniglide stuff) and I also got a new 46 ring - the changes brought my top gear up to 95" which is sufficient for me. 42/11 is also around 95" depending on the size of the tire (the change from a fat knobby to a narrow slick can change your gearing by as much as 8%!)

I'd go with either the 11-19 or 11-21 if you can find it. 32/19 is about 42" which should be plenty low on relatively flat terrain for someone who is in good shape. Then there's always the granny for a 22/19 low (about 29") which is more than low enough for almost any terrain for someone who is in shape.

fuzz2050

You could always just replace the outer chainring. There is a pretty good chance it's just a 110 bcd, and in that case there are no shortage of options.

dwr1961

Thanks, Gonzo , Fuzz...

While Fuzz's idea of replacing the big ring might actually be the cheapest option (I havent priced a 48-tooth 110 BCD ring yet) I don't see it as a better one. Follow my reasoning:

We know my friend uses his largest gear combo (42x13) almost exclusively for his morning ride. That big ring-small cog pairing gives him 84 gear-inches according to the chart I had to scrounge around to find thanks to Fuzz's proposal...

Let's assume that the best solution is the one that would provide the most gearing combos above the 84 inches currenty offered:

First let's change out the big ring to a 48 and leave the current 13-30 cassette:

New top gear: 48x13 = 96 (great!); next ratio 48x15 = 83 (about equal to current highest)

Thus we get one higher (albeit a MUCH higher) gear for our investment...


Scenario 2: Leave the current crank with its 42 tooth big ring and change the cassette to a 12-21:

Top 42x11 = 99 (even higher than option 1); next 42x12= 91 (still an 8%) improvement); and finally 42x13 = 84 (back where we started).

I think this second solution is the winner... We've got three tall but close-ratio gears at or above the original highest combo. Plus, I don't have to pull the crank; I can simply swap out the cassette...

So I guess I'm still looking for one of those mysterious 11-21's or even 11-19's... Keep those suggestions or sources coming!

Thanks again, guys.

Gonzo Bob

The crank can't be 110BCD because the smallest ring for that is 33 and the middle on your friend's crank is 32. It might be a 94/58 BCD 5-arm. That's what mine is but I really had to search for a 46 (I think I ended up getting it from Ben's Cycle eBay store). I don't know if you can get a 48 for 94mm BCD. It could also be a 4-arm crank. I think larger ring availability is even less for those. Also, some MTB cranks have the rings riveted (or fastened in some other more permanent fashion) to the crank and it may not be easy to change one.

Bill Kapaun

Time for a Custom Cassette!
He has-
13-15-17-20-23-26-30
Buy an 11-19, which has-
11-12-13-14-15-17-19
Use his 20 in place of the 19. Not quite 21, but close.

The cheaper SHimano cassettes just have 3 rivets holding the 6 largest cogs & spacers together. About 5 minutes with a file (they are soft steel) to file the heads off on one side and they can easily The driven out.The way the individual cogs are splined, you can't put them together "wrong".

One caveat regarding 11T cogs.
SOME Free Hub bodies don't accept them without grinding down the ends of the splines.
You really should make sure he has a "COMPACT" FH body which is designed to accept 11T cogs.

https://sheldonbrown.com/gloss_ho-z.html#hyperdrivec

fuzz2050

Good call, I had forgotten all about those that. The 94/58 because they just don't show up too often, and I refuse to acknowledge the existence of those 4 arm monstrosities. For my money, it's hard to beat 110/74 as a BCD, it provides you the possibility of a road double, a road compact, a wide range compact (48/22) or a triple. It's also not stupid expensive to buy rings (I'm looking at you TA).

That however is all besides the point, I think a custom cassette is in order.

dwr1961

Thanks for the info, Bill and Fuzz... I'ts been a couple days since I checked this thread. I appreciate the expert info...

The labeling on the crank in question designates it as a Suntour PowerRing ND - Micro Drive System (I'm personally not familiar with early-90's components. They're BC --- Before Cycling --- for me). It's a 5-arm setup and looks to be of good quality.

I'll look into what type of freehub body he has... I think the "custom" route is an intriguing option. I'll post the final resolution to this whole issue when we get to that point.

Thanks again for the input.

Bill Kapaun

Have him do a "test" to see what the lowest gear he needs is-
IF he can get by using the middle ring and 2nd gear (or higher), he can get by with the small ring and a 19T cog (11-19)
IF he needs middle ring and 1st gear, he can get by with the small ring & 21. (12-21)

IF he needs the granny ring, he'll need bigger than 21. IF so, have him determine the smallest cog he can use with the granny to get him up his worst hill.

dwr1961

This is an old rigid-fork bike that's being (now) used exclusively on the road in an area of flat to very gently rolling terrain. His usual ride is a one-mile loop that features a short 2-3% up-downgrade section and is otherwise pancake flat.

The middle ring gets rare use. The small ring is never used.

Bill Kapaun

I'd just go to the 11-19 and call it good. That way you wouldn't have to disassemble the cassette to add a cog that's only 1 tooth larger. He could use the middle ring to take off and shift to the big when he felt like it. Middle 1st would be just slightly higher than his current big 2nd. (43.8 vs 42 Gear-Inches) On the big ring @ a cadence of 90, his speed would be about- 11T = 26.6 12T = 24.4 13T = 22.5 MPH. Any of those speeds is "zipping along" for a mountain bike. I have a hunch he should also work on raising his cadence.

bobbyl1966

For which terrain is the 11 and 12 cog? For downhills only or is okay for flats too. Which cassete 7 speeds is good match for crank 52/42?

shelbyfv

You just don't get it do you?

HillRider

You realize this thread is over 5 years old? The answer to your question depends on the rider and where they ride. A strong rider can use a 52x11 or 12 on flat or slight downhill roads. A weak rider can't turn gears that high effectively. How strong are you and what kind of terrain do you ride? How steep are the hills you have to climb?

bobbyl1966

I do use 53-12 on flats. I ride most is closer where i live in one bike trail have elevation from 700 feet to 900 feet. My road bikes i have two i use same wheels in both bikes and crank and cassete. I have 53/39 and 12-25 9 speeds cassete. But the rim tape when i put air in the tires is move is weird do that is have blow that way 7 innertubes new rim tape not help. For now i ride my mountain bike in that hilly trail. I take out the 48/38/28 crank i put crank 52/42. I have 7 speeds cassete 13-26, I tried one hill i do fast with the 52-26 and i tried the 52-23 is was harder but i do that hill and i stayed on the seat. Is short hill but is steep. I am strong rider just i really dont know how to pair crank size with cassete size and i need help in that. In that bike trail is 10 miles long i used to do around 50 minutes do that 10 miles. I try setup my bike better for i do that ride in less time.