Bicycle Mechanics - Custom SRAM cassette--can I use two spiders?

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marathon_affe
09-12-10, 08:22 PM
I just completed an drivetrain upgrade to SRAM Apex and now I'm looking to tweak the cog spacing to better suit my abilities / terrain.

I have a PG-1070 11-32 cassette, and my idea was to take off the 12, 19 and 22 loose cogs off and replace them with the 19-21-23 spider from the 11-23 cassette. I would have to purchase this second cassette so I can't check to see if the spider's spacing would allow me to mount it in a middle position. Does anybody know if this might be possible?

Tyler


urbanknight
09-12-10, 09:51 PM
I don't know the details of Apex specifically, but most cassettes have a good number of the larger cogs riveted together. One of the few brands that have completely individual cogs is Miche, so if you want to customize your cassettes, look into them.

Also, if I followed you correctly, you want a cassette that goes 11-19-13-15-17-21-23-25-28-32. WTF?

AEO
09-12-10, 10:42 PM
you want to mix an 11, 12, 13, 14, 15, 16, 17, 19-21-23 with a 11, 12, 13, 15, 17, 19, 22, 25-28-32
to make 11, 13, 15, 17, 19-21-23, 25-28-32?

the spider design is most likely the same for the 11-32 cassette, so take it off and see if you can't place the 25-28-32 in front of the 19.
guesstimate spacing with a measure.


urbanknight
09-12-10, 11:42 PM
you want to mix an 11, 12, 13, 14, 15, 16, 17, 19-21-23 with a 11, 12, 13, 15, 17, 19, 22, 25-28-32
to make 11, 13, 15, 17, 19-21-23, 25-28-32?

Ah, I see what he was saying now. I'm pretty sure you can't put a #3 position cog in the #2 place. The 1st and 2nd cogs are specific.

Bezalel
09-13-10, 12:34 AM
Ah, I see what he was saying now. I'm pretty sure you can't put a #3 position cog in the #2 place. The 1st and 2nd cogs are specific.

Not always. The 12 tooth cog in the Tiagra 12-25 9-speed cassette is the same as in the 11-32 Deore 9-speed cassette.

Chris_W
09-13-10, 12:41 AM
This is why I think SRAM Apex (compact crank and MTB cassette) is a stupid idea - the gear spacing is too wide for normal road use. A triple crank and well-spaced rear cassette is a far better solution for most people.

Having got that off my chest, I'll add something more useful. It's true that the 2nd position cog is special, so you'll need a 13-tooth cog designed for the second position, which you could get from a 12-23 cassette (or any other 12-xx cassette). Actually, why keep the 11-tooth at all? Why not go with 12-13 as the top two gears (50-12 is plenty big enough gear if you learn how to spin the pedals - I pedal my top gear of 48-12 at up to 65 kph / 40mph). After you've sorted that out, you'll have to figure out what spacer you need behind the 19-21-23 spider to make the gap to the 25-tooth correct, the standard 10-speed spacer will not be wide enough - you could add one or two of the 1mm spacers that come with Shimano 10-speed cassettes, or try an 8-speed or 9-speed spacer instead of the 10-speed one, or any combination of those.

marathon_affe
09-13-10, 06:45 AM
Thanks for all the replies. I had forgotten that the 2nd cog is also special and can't be pulled as easily as I mentioned.

AEO: Yes, that's roughly the plan (though I'd have to go 11-12-15 due to the 2nd cog). Thanks for pointing out the obvious on moving the spider inboard. I'll give that a try.

Chris_W: Naturally I disagree about triple vs. Apex but I hear you on all the rest. Ideally I would ditch the 11 but doing so makes things a little trickier as none of the 12-xx SRAM cassettes give me anything unique in the higher cogs. For simplicity's sake, I'd prefer to keep everything SRAM and not start mixing in Shimano/Miche cogs but if people have had positive experiences going that route I would reconsider.

Tyler

fuzz2050
09-13-10, 12:27 PM
For simplicity's sake, I'd prefer to keep everything SRAM and not start mixing in Shimano/Miche cogs but if people have had positive experiences going that route I would reconsider.

Tyler

I have built entire cassettes using whatever cogs I had that showed the least wear, and I ended up with a nice mix of Shimano, Sram, and a few off-brands that still shifted well. Of course, I was using friction: I would be a little scared to try to index such a Frankenstein cassette.

AEO
09-13-10, 02:11 PM
from my experience, you can mix shimano and sram cogs and lock rings, but you can't use sram cog spacers in that mix, because they're shaped as an interlocking design.