Cassette & Sprocket Selection-Combination Question

Farrell said:

Yes, I want a combination Shimano does not make! I had no idea this was
possible. What I would like to do is buy the 9-speed CS-901 - Ultegra 9
(11-23), remove the three larger sprockets and replace them with 20, 26 and
34-tooth sprockets to make a 11/12/13/14/15/17/20/26/34.

Is this possible to do? Will the larger tooth difference between adjacent
sprockets cause shifting problems? I don't really care if it slows shifting
up a bit - just so long as it will shift eventually - I only use those
sprockets on big hills.

One option: IRD sells 11-32 ...
http://www.interlocracing.com/cassettes_steel.html

The combinations:
http://www.interlocracing.com/cassbreakdown.html

11, 12, 14, 16, 18, 20, 24. 28. 32
12, 13, 14, 16, 18, 20, 24. 28. 32

The issue is these wide ranges likely exceed the range on the
derailleur, so you need to be really careful to not cross-shift.
(big-big, maybe small-small, depending on chain length).

To not-really answer your question: Shimano derailleurs can handle
fairly large jumps, but 8 teeth is exceptional.

On Feb 12, 9:22 am, Dan Connelly <d_j_c_o_n_n_e_l@y_a_h_o_o_._c_o_m>

Quoted message said:

To not-really answer your question: Shimano derailleurs can handle
fairly large jumps, but 8 teeth is exceptional.

That was my thought also. The Shimano Megarange 7-speed freewheel:
http://www.sheldonbrown.com/harris/freewheels.html#7 has a 24-to-34
jump, but it is usually combined with a Megarange derailleur. I don't
know if that derailleur is tweaked to handle that shift.

Jeff

"Farrell" <[email hidden]> a écrit:

Quoted message said:

What I would like to do is buy the 9-speed CS-901 - Ultegra 9 (11-23),
remove the three larger sprockets and replace them
with 20, 26 and 34-tooth sprockets to make a
11/12/13/14/15/17/20/26/34.

The 17t and 19t sprockets are mounted together on a spider (as are the 21t
and 23t) so you'll need to replace the 17t as well if you change the 19 to a
20. Do you need the 11t? Starting 12-up would either get you a 16t in the
main range, or tighter spacing between the big sprockets.

Quoted message said:

Is this possible to do? Will the larger tooth difference between adjacent
sprockets cause shifting problems? I don't really care if it slows
shifting up a bit - just so long as it will shift eventually - I only use
those sprockets on big hills.

Yes it's possible: Shimano's Megarange cassettes do just that. You'll need a
mountain bike derailleur.

James Thomson

James Thomson said:

"Farrell" <[email hidden]> a écrit:

Quoted message said:

What I would like to do is buy the 9-speed CS-901 - Ultegra 9 (11-23),
remove the three larger sprockets and replace them
with 20, 26 and 34-tooth sprockets to make a
11/12/13/14/15/17/20/26/34.

The 17t and 19t sprockets are mounted together on a spider (as are the 21t
and 23t) so you'll need to replace the 17t as well if you change the 19 to a
20. Do you need the 11t? Starting 12-up would either get you a 16t in the
main range, or tighter spacing between the big sprockets.

Quoted message said:

Is this possible to do? Will the larger tooth difference between adjacent
sprockets cause shifting problems? I don't really care if it slows
shifting up a bit - just so long as it will shift eventually - I only use
those sprockets on big hills.

Yes it's possible: Shimano's Megarange cassettes do just that. You'll need a
mountain bike derailleur.

James Thomson

I have a 14-24 + 32 arrangement built up in just this way. Works fine
with a deore derailleur. Gives a huge range on a 50-38 double up
front. Of course, 99.9% of the time the 32 at the back isn't used, so
never needs replacing, but the 0.1% (0.001%) of the time when it is
needed it's fantastic.

So yes. Your proposed setup will be fine.

Farrell said:

I wish to order a new casette for my bicycle with optimized gears. I was
looking at the Harris Cyclery website that describes available 9-speed
Shimano-compatible cassettes http://sheldonbrown.com/harris/k7.html#9There
is a section on that page addressing loose sprockets. It states:

"Do you want a cassette combination Shimano doesn't make? We carry many
individual sprockets for Shimano cassettes, and can provide most sizes. The
most economical approach to custom cassettes is to buy a stock cassette that
has most of the gears you want, then an additional sprocket or two to
substitute for the un-wanted sizes."

Yes, I want a combination Shimano does not make! I had no idea this was
possible. What I would like to do is buy the 9-speed CS-901 - Ultegra 9
(11-23), remove the three larger sprockets and replace them with 20, 26 and
34-tooth sprockets to make a 11/12/13/14/15/17/20/26/34.

Is this possible to do? Will the larger tooth difference between adjacent
sprockets cause shifting problems? I don't really care if it slows shifting
up a bit - just so long as it will shift eventually - I only use those
sprockets on big hills.

My objective in this cassette selection and modification is to have very
tight gear spacing for normal speeds (I like 5% to 8% gear changes - 10%+ is
more than I like), but not compromise hill climbing ability. I realize this
gearing will limit finding an optimal gear for a given hill, but I am
willing to sacrifice that for the tight gearing on the flats (I live and do
most all my riding in Florida). I don't care how fast I go up a hill, just
as long as I have the gear to do it at some speed.

I am also aware of the half-step gearing approach to get tight gear spacing.
I have the half-step setup now on my other bike (and love it!), but the bike
I want to put this cassette on has a Rotor Crank (which I love!) and
unfortunately one cannot set up half-step gearing with the avaiable
chainrings for those cranks.

Anyone have any experience with this type of cassette modification?

Thanks.

Terry Farrell
Farrell Piano

www.farrellpiano.com
[email hidden]

Long ago I ran a 7 speed setup with 12-14-16-18-21-24-32 with half
step outer-middle rings and bar end shifters. Worked well enough.
You could tell when going from the 24 to 32. On my setup the gap
between 24 and 32 was missed a lot. Eventually went to a
14-16-18-21-24-28-32 that was much better. Deore DX rear derailleur.
I've run a 9 speed short cage Campagnolo with
13-14-15-16-17-19-21-23-28. 5 tooth jump was not a problem. Sligh,
slight hesitation, but the two times a year I went into the 28, it did
not bother me. Shimano HG50 and HG70 cassettes are all loose cogs I
think so you can mix and match somewhat. Try to get as many
consecutive cogs from one cassette as possible. You will notice the
change from one cassette to the other. Some changes more than
others. So its best to keep this change to a minimum of one and as
far to one end of the cassette as possible. Not between the two cogs
you use the most.

"James Thomson" <[email hidden]> a écrit:

Quoted message said:

"Farrell" <[email hidden]> a écrit:

Quoted message said:

Quoted message said:

What I would like to do is buy the 9-speed CS-901 - Ultegra 9
(11-23), remove the three larger sprockets and replace them
with 20, 26 and 34-tooth sprockets to make a
11/12/13/14/15/17/20/26/34.

Quoted message said:

The 17t and 19t sprockets are mounted together on a spider (as are
the 21t and 23t) so you'll need to replace the 17t as well if you change
the 19 to a 20.

I was cleaning one of these cassettes at the weekend, and noticed that the
17 and 19 are actually normal splined sprockets riveted together with a
spacer, so they can be separated and used singly by drilling out the rivets.

James Thomson