Non-standard Cassette?

[MacB]

Nick, for me this was all based on trying to create a compact double for road riding that would be what I wanted. I was basing it on the middle ring I currently do nearly all my riding on plus a smaller inner ring. As I found last night it's nothing new, Sheldon used to set bikes up like this, this article refers to his multi range gearing and using a 50/28 combo up front:-

http://sheldonbrown.com/gear-theory.html

to be fair the chainset has been my big headache not the cassette

 

[NickM]

Been there, done that, much prefer a triple with crossover gearing!

 

[MacB]

Been there, done that, much prefer a triple with crossover gearing!

Maybe it's my riding style then, but I've easily done 95% of my riding in the 42t middle ring, the 30t inner has been employed when the going gets steep. Barring a blief flurry on one night ride the 52t ring remains virginal. I even considered whether the 52 could be replaced with a bash guard.

Perhaps it's that I still ride as I did when I was young and had very limited gear choices.

When the my 3 bikes are complete I'd envisaged 1 x Rohloff, 1 x the Sheldon compact double style and 1 x 9 speed single ring.

 

[PpPete]

Been there, done that, much prefer a triple with crossover gearing!

Nick -what do you mean by "crossover" gearing?
I thought when you first mentioned it I understood what you meant, but looking at the ratios from the gearing you mentioned in your other post I'm not sure now.

 

[PpPete]

You'd do it cheaper by getting a road 9sp cassette and a MTB one, pulling them apart and taking the cogs out of them you need.

Some Shimano cassettes have the whole block held together with long allen bolts so are easily disassembled.
Others have the whole lot riveted together, or have half riveted together and the other cogs loose - just grind/drill the tops off the rivets and separate.

The cassette will work fine on the bike with just loose cogs, it's held in place by the hub splines and the lockring

The smallest cog is the one which matters, as it's the one with the lockring, but just get a couple of cassettes with the ratios you want included in them.

e.g. Tiagra 9sp £14.99 at CRC http://www.chainreactioncycles.com/Models.aspx?ModelID=387
12-23 - 12.13.14.15.16.17.19.21.23
12-25 - 12.13.14.15.17.19.21.23.25
13-25 - 13.14.15.16.17.19.21.23.25
14-25 - 14.15.16.17.18.19.21.23.25

e.g. Deore 9sp £19.99 http://www.chainreactioncycles.com/Models.aspx?ModelID=443
11-12-13-14-16-18-21-24-28
11-12-14-16-18-21-24-28-32
11-13-15-17-20-23-26-30-34

That's sort of what I was thinking to do....
How easy is it to drill those rivets out?
And it still leaves me lacking a 27

 

[NickM]

Crossover: each chainring has a range of gears (this is truer in the era of 9-speed transmissions, with 7 usable on any ring, than it was in the days of 5/6/7 speeds).

You simply ride in the chainring best suited to the terrain, seldom changing chainrings. Most of your gear changes are made with the rear derailleur, which works more smoothly than the front. When you run out of usable gears on the ring you're in, you change rings in the appropriate direction and just stay on the new ring until you run out of gears again.

You get as many gears as you need, and minimal brain strain selecting the right one!



MacB's wide-range double is also easy on the brain, but the shift between rings is not nice because of the huge gap, and it lacks either the top gears or the close ratios you can have with a triple. Just my opinion (having tried most setups by now), of course...

 

[andy_wrx]

How easy is it to drill those rivets out?
And it still leaves me lacking a 27

They're really soft - I used a punch to give the drill something to start on and them simply drilled-out the end out with a powerdrill and HSS bit, making sure I just drilled the (head ? tail ? - the end flattened-off when it's inserted, not the domed-end it's made with) off and not into the cog itself (although as it's the biggest cog, there's lots of metal and not really an issue)

I can't instantly find someone who's stocking them, but there's a 105 HG70 12-27 : 12-13-14-15-17-19-21-24-27

See Sheldon : about halfway down 'Building Custom Cassettes'
http://sheldonbrown.com/k7.html
- this is exactly what he's advocating

 

[PpPete]

Aha - thanks Nick, kind of how I ride, minimal brain strain is very necessary at the end of a long ride.

Just going back to your previous... I've not tried a 11-28 yet, so I don't know for certain, but some of the individual jumps on that stock cassette are close to 17% which I know feels like too much of a gap on my 7 speed. I often use that bike on one particular flat which is susceptible to headwinds in both directions, going up and down the gears, wishing I had something in the middle of that gap.

I've been playing with ratios for hours, trying to keep to around or below the 14% jump of a Rohlhoff (not that I've ever tried one of those, or ever likely to be able to afford one) but still have the biggest overall range possible.

 

[NickM]

The big jump at the bottom of the 11-28 I think is fine - when you are going slowly enough to need bottom gear, you stall a little while changing down, so the reduction in gear needs to be on the generous side.

The bigger-than-ideal difference between the 18 and 21 sprockets - well, that's because you can't have a fraction of a tooth! No gear system based on toothed cogs will ever be theoretically perfect... but after years of poring over spreadsheets I've come to the conclusion that (for touring, anyway) if bottom gear is low enough, and the gears you use most are readily accessible one from another, the rest aren't likely to be a problem with a 9-speed cassette.

 

[bonj2]

pete, you need to think of a pair of cassettes that we can butcher to make my perfect cassette and your perfect cassette out of the remains...
using steve austins deremmelling suggestion
I want 14-28 you want 12-30

 

[Alf]

The big jump at the bottom of the 11-28 I think is fine - when you are going slowly enough to need bottom gear, you stall a little while changing down, so the reduction in gear needs to be on the generous side.

The bigger-than-ideal difference between the 18 and 21 sprockets - well, that's because you can't have a fraction of a tooth! No gear system based on toothed cogs will ever be theoretically perfect... but after years of poring over spreadsheets I've come to the conclusion that (for touring, anyway) if bottom gear is low enough, and the gears you use most are readily accessible one from another, the rest aren't likely to be a problem with a 9-speed cassette.

I entirely agree, that's the right approach. I would also find the 18-21 gap too big and would choose the 12-27 as about the widest spread cassette I would be happy with on a long ride. But different riding styles differ on that.

Having chosen your cassette using your best compromise, choose the rings to give you the range you need. The only other ingredient to have a bit of an eye on is the smallish range of gears you use most. If that range lies close to a point where you have to change ring and then a couple of sprockets as well, it could be a bit of a pain. The ideal would be to have the most commonly used gears in the the middle of the cassette - might be tricky though if you are trying to get a wide range and closish ratios at the same time.

Alf

 

[PpPete]

pete, you need to think of a pair of cassettes that we can butcher to make my perfect cassette and your perfect cassette out of the remains...
using steve austins deremmelling suggestion
I want 14-28 you want 12-30

Seen my suggestion for a "Sprocket Library" in the Feedback section ?

Although I'd be happy to try & work a combination out individually with Bonj - if he's prepared to contribute his dremel, I don't have one, and the investment would be similar to a made-to-measure Marchisio!

 

[andrew_s]

In the longer term a Marchiso setup may not cost any more than a cassette made up from parts of other cassettes.
When it comes to replacement time, with Marchisio you just replace the two or three most worn sprockets, but with combined cassettes you have to get a whole new cassette, or possibly two. After a while you'd also end up with a whole heap of unused or only slightly worn 11T sprockets.

 

[bonj2]

Seen my suggestion for a "Sprocket Library" in the Feedback section ?

Although I'd be happy to try & work a combination out individually with Bonj - if he's prepared to contribute his dremel, I don't have one, and the investment would be similar to a made-to-measure Marchisio!

well i'll tell you what "you design, i build".
if you can come up with two cassettes that'll give me a 14-28 and you a 12-30 then i'll happily do the dremelling

 

[bonj2]

They're really soft - I used a punch to give the drill something to start on and them simply drilled-out the end out with a powerdrill and HSS bit, making sure I just drilled the (head ? tail ? - the end flattened-off when it's inserted, not the domed-end it's made with) off and not into the cog itself (although as it's the biggest cog, there's lots of metal and not really an issue)

I can't instantly find someone who's stocking them, but there's a 105 HG70 12-27 : 12-13-14-15-17-19-21-24-27

See Sheldon : about halfway down 'Building Custom Cassettes'
http://sheldonbrown.com/k7.html
- this is exactly what he's advocating

the depth of sheldons knowledge never ceases to amaze me.