Non-standard Cassette?

[PpPete]

OK so i've been playing about with different gear set ups on various bikes, and reading all the advice on here and elsewhere.

I've now settled on 9 speed on the basis that it's more durable and lower cost than 10 speed, and triple (because it gives a greater range for me tired old legs - without constantly double shifting). I'm not embarrassed about having and using a granny ring because even the "best bike" is a steel framed tourer (Highly modified 1987 Galaxy FWIW). Oh yes and all Sh*m*no.

I don't need very close ratios like a true roadie, but equally I want to avoid big jumps (I've got some on my hack bike which has a 7 speed cassette - and I know I just don't cope well with a big change in ratio)

What I came up with as my ideal cassette would be 12,13,15,17,19,21,24,27,30.
or (with different chainrings)
13,15,17,19,21,24,27,30,34

But as far as I can establish no-one makes such things.... which is odd because they are far more evenly spaced than the more common cassettes such as 11-32, 11-34 or even 11-28.

I suppose I'm falling in to that grey area between road & MTB.

Any ideas anyone? & don't say Rohlhoff, because that's so far beyond my budget as to be out of the question... and no drops.

 

[MacB]

Pete, been there and it's a pain, Sheldon gives some advice on modifying, so you should be able to cobble seperate cassettes together, obviously that raises the price. I think the smallest cog needs to be of different design, maybe a lockring type?, so you need to source these in 12 or 13t. Shimano do a 12-34 but only in the top end MTB range and is mega bucks.

When I was searching I kept finding reference to places that would make custom casettes, but I've not actually found anywhere yet. Strange because you'd think they'd do a roaring trade. The insistance on an 11t small cog really messes up the gearing options I'd like.

Thinking on it maybe you could get a 12-27 road cassette and modify that?

 

[MacB]

this is the Sheldon article:-

http://sheldonbrown.com/k7.html

I note that Harris Cyclery no longer offfer their custom cassette option

 

[MacB]

maybe I lied, custom cassettes at Harris here:-

http://www.sheldonbrown.com/harris/k7.html

wouldn't be cheap but would imagine they'll put together what you want

 

[MacB]

new article on Bike Radar here:-

http://www.bikeradar.com/gear/article/workshop-fitting-replacing-cassette-sprockets-18234

still surprised I can't find anywhere offering this service

 

[MacB]

Found somewhere, £90 though for the cassette, but looks like you make what you want up to a 30t

http://www.etailsport.com/custom_cassette_9speed.htm

 

[PpPete]

Thinking on it maybe you could get a 12-27 road cassette and modify that?

Yes, taking the 14 out of a 12-27, and putting a 30 on the back would do it, but the 12-27 is already a relatively expensive cassette, and whilst SJS do plenty of spare small sprockets (at a price) they don't do a 30, so i'd have to buy 11-34 and dis-assemble.

BTW How do you take apart the back few sprockets that come mounted together? Is is just a question of hitting those pins with a drift? Are any currently available cassettes bolted together so they can easily be taken apart?

 

[MacB]

Yes, taking the 14 out of a 12-27, and putting a 30 on the back would do it, but the 12-27 is already a relatively expensive cassette, and whilst SJS do plenty of spare small sprockets (at a price) they don't do a 30, so i'd have to buy 11-34 and dis-assemble.

BTW How do you take apart the back few sprockets that come mounted together? Is is just a question of hitting those pins with a drift? Are any currently available cassettes bolted together so they can easily be taken apart?

I'm a theory guy only on this matter, if I do it then it'll be under close supervision of mechanic the first time The guy at my LBS was bemoaning this very subject last week. That he used to be able to just throw together whatever combo a customer wanted.

 

[PpPete]

Found somewhere, £90 though for the cassette, but looks like you make what you want up to a 30t

http://www.etailsport.com/custom_cassette_9speed.htm

Ouch ! And there's me trying to find ways of doing it for a third of that price (cheapskate that I am)

Thanks for the link though, it's another option.

 

[MacB]

Ouch ! And there's me trying to find ways of doing it for a third of that price (cheapskate that I am)

Thanks for the link though, it's another option.

bit wary of the site though, lot's of categories and many empty ones, is new startup so maybe genuine.

The only way I can think of doing it cheaply is via a group of people all wanting custom cassettes and pooling resources. But I'd be concerned that there wouldn't be enough diversity of requirement.

 

[PpPete]

SJS do plenty of spare small sprockets (at a price) but they don't do a 30, so i'd have to buy 11-34 and dis-assemble.

T'interweb is a wondrous beastie!
As soon as I realised the answer might lie with Marchisio, and googled further I came up with this for the 30T

And Parker will build up a complete Marchisio for £93.71 which I can't afford at the moment. Anyone any experience of Marchisio cassettes?

 

[NickM]

The guy at my LBS was bemoaning this very subject last week. That he used to be able to just throw together whatever combo a customer wanted.

Ah, but in the days of 5, 6 and 7-speed clusters and "interesting" gearing setups like "Alpine" and "Half-step-plus-granny" there was a perceived need to do that.

Now, with 9-speed cassettes, everybody rides Crossover gearing - and it's a good thing! Lots of ratios, lots of duplication, yes, but a dead easy shifting pattern that works fine even when you're sagging. On a touring bike you have a range of gears on the big ring, another range (say) two gears lower on the middle ring, and another range (say) three gears lower again on the small ring. So a change from big to middle is worth two sprockets, and a change from middle to small is worth three (because when you reach the foot of a hill steep enough to require the small ring, you need a bigger jump downwards).

For example: 46/36/24 with the very useful 11/12/13/14/16/18/21/24/28 (Shimano SLX) cassette suits me fine for touring.

There are loads of 9-speed cassettes available, most of them quite sensible; and 9-speed chain has sufficient side-to-side flex to allow the use of seven sprockets with each chainring without excessive wear. As long as you can afford appropriate chainrings, you can get very close to your ideal setup with one standard cassette or another.

 

[PpPete]

Nick - Agree with you about the importance of getting the chainrings right - and using 7 of the 9 sprockets with each chainring....

But for me the issue with the standard 11-28 cassette is that it has a couple of big jumps in it: 18-21 and 24-28 on which the "overlap" between the chain rings is of no help.

 

[andy_wrx]

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

 

[NickM]

...for me the issue with the standard 11-28 cassette is that it has a couple of big jumps in it: 18-21 and 24-28 on which the "overlap" between the chain rings is of no help.

Well, if this issue is based on riding experience, fair enough. In that case, you'll need a cassette with a closer spread than the 255% of the 11-28 (a 12-27, perhaps?), and (possibly) wider-spaced chainrings to compensate.

If it's based on looking at ratios in theory, though, you may well find that it isn't much of an issue in practice...