Ultra Poormans XX1

[Flowta]

That 41 sprocket looks like it could weight quite a bit. looks very similar to a motorbike sprocket actually.

 

The re assembling of the cassette by your drill and tap method will be crucial. get that wrong and it will be a recipe for disaster. Are you sure there is enough material on the bigger sprocket to adequately fasten down the rest of the sprockets? Where would you find the torque specifications for this application?

 

I'm only being critical because you've come onto a great idea that I might try myself but obviously wary as it's untested until now, looks neat but the proof is in the pudding as they say.

 

It's not 100% necessary for the sprockets to be fixed together. (As akneethling has pointed out)

 

There is more than enough meat there to tap a thread.

 

WRT torque requirement, if you look at a standard Deore cassette, you'll see that there is some play between the sprockets, the pins basically hold the cassette together for ease of installation.

[Flowta]

brilliant write-up, does it weigh a lot? looking forward to your after ride write-up.

Is stainless steel and weighs 150g

 

Shaper has pretty much covered this. Once I've done the drilling and tapping, I'll weigh the whole cassette.

 

Obviously if you start with a lighter cassette (eg XT, XTR, etc.) you'll end up with a lighter overall cassette weight

[Captain Fastbastard Mayhem]

Is it really Necessary to bolt the big sprocket to the rest of the cassette? The Lock Nut, torqued to 40nM should hold it in place, and the Free Body would keep it aligned in the Drive Direction.

 

Yes. It is necessary...

 

Reason? If it weren't bolted together, every time you were in 1st, your sprocket would have a 1mm/2mm contact point on the free-hub body, versus the whole width of the cassette as a contact point if they were bolted together.

 

What that means is that if it were unattached, it'd have a propensity to damage the freehub far quicker than if t were attached to the rest of the cassette due to the limited contact patch size.

 

(or am I totally off the ball here, Flowta?)

[akneethling]

Yes. It is necessary...

 

Reason? If it weren't bolted together, every time you were in 1st, your sprocket would have a 1mm/2mm contact point on the free-hub body, versus the whole width of the cassette as a contact point if they were bolted together.

 

What that means is that if it were unattached, it'd have a propensity to damage the freehub far quicker than if t were attached to the rest of the cassette due to the limited contact patch size.

 

(or am I totally off the ball here, Flowta?)

There would be more pressure on the freebody (Same Force-Smaller contect area). But that is an issue with the free body. Some manufactures have included an Anti Bite Guard with their Free Bodies. Some free Bodies dont even wear from cassettes.

 

PS. Look at the SRAM cassettes. They are not bolted together at all.

[Helpmytrap]

Yes. It is necessary...

 

Reason? If it weren't bolted together, every time you were in 1st, your sprocket would have a 1mm/2mm contact point on the free-hub body, versus the whole width of the cassette as a contact point if they were bolted together.

 

What that means is that if it were unattached, it'd have a propensity to damage the freehub far quicker than if t were attached to the rest of the cassette due to the limited contact patch size.

 

(or am I totally off the ball here, Flowta?)

I'm with you on this one considering what the bottom 4 "loose" cogs do to the freehub, and I don't think one puts them under nearly as much force/torque as you do on the top end of the cassette when grinding out a steep hill.

 

My other worry would be as someone mentioned, is for the 41T to warp/bend. If it isn't fixed to the cassette it only has support on one side and under enough force will bend because nothing prevents it from flexing inward towards the spokes.

[shaper]

in this article http://www.bentrideronline.com/?p=8631

 

"The overall quality of the MTB Tools cog is pretty good but not excellent. There were some small burrs on the teeth and the finish is a bit rough. However, this is a consumable part that will soon be covered in chain oil and the burrs all wore off within a ride or two, so that’s not a major concern. The more shocking thing was that it weighs a whopping 150 grams. That may not sound like much but it’s a third of a pound! The entire cassette only weighed 330 grams before I messed with it.

 

Installation was initially quite easy. I removed the stock ten-speed cassette, tossed aside the 11T small cog and the original lock ring, put the MTB Tools cog on the wheel and reinstalled the cassette with the new larger lock ring. This now gave me a 12-41 cassette."

 

He did not tap the 41 cog to the cassette... and I guess it is not much different to the 11, 12 or 13 which are often single cogs in a cassette, so there may be no need for it to be tapped (other than piece of mind)

[Flowta]

Yes. It is necessary...

 

Reason? If it weren't bolted together, every time you were in 1st, your sprocket would have a 1mm/2mm contact point on the free-hub body, versus the whole width of the cassette as a contact point if they were bolted together.

 

What that means is that if it were unattached, it'd have a propensity to damage the freehub far quicker than if t were attached to the rest of the cassette due to the limited contact patch size.

 

(or am I totally off the ball here, Flowta?)

 

Yes and no, if you have a steel freehub or one with anti-bite guard, then run single sprockets at will. If you look at some single speed kits, the sprockets is literally a 2mm steel sprocket, no more, no less.

 

FYI, I will be retrofitting my alu freehub with my own anti-bite guard. How-to to follow when get round to it.

 

Also as I wrote earlier, if you look at a Deore cassette, it is not tightly held together. Most of the "tightness" is from the lockring.

 

When I am done it will be a lot tighter than a standard Deore cassette.

 

Also bare in mind that the 41tooth sprocket is made out of 3mm steel (will double -check this evening) and the chafered at the teeth.

[Flowta]

I'm with you on this one considering what the bottom 4 "loose" cogs do to the freehub, and I don't think one puts them under nearly as much force/torque as you do on the top end of the cassette when grinding out a steep hill.

 

My other worry would be as someone mentioned, is for the 41T to warp/bend. If it isn't fixed to the cassette it only has support on one side and under enough force will bend because nothing prevents it from flexing inward towards the spokes.

 

This I will be doing, but it the steel is a lot thicker then a standard sprocket (+-3mm)

[DJ84]

I would like to try this with a 9 speed,

maybe only go to a 38tooth sprocket as I am riding 44-32 from and an 11x32,

so essentially a 1:1 ratio for climbing.

 

Do you think the long cage XTR 9speed would handle a 38 cassette?

[Captain Fastbastard Mayhem]

I would like to try this with a 9 speed,

maybe only go to a 38tooth sprocket as I am riding 44-32 from and an 11x32,

so essentially a 1:1 ratio for climbing.

 

Do you think the long cage XTR 9speed would handle a 38 cassette?

 

Absolutely.

[DJ84]

Absolutely.

 

Awesome,

This will be my end of year project.

 

Just to try figure out if I should ride a 36 or 38 upfront.

[nolipoli]

This big seperate cog has no shifting ramps? Surely this affects shifting performance badly.

 

I think I am just going to wait for a few more options in the aftermarket.

[LuckyLuke]

I see there is an 38 teeth available aswell, The jump would not be as big as to 41. Anyway, this is a great idea for that training wheelset, will outlast the alu cassettes and the racing rear wheel can be fixed with the general lee adapter if you have some free mulas lying around.

[Flowta]

I see there is an 38 teeth available aswell, The jump would not be as big as to 41. Anyway, this is a great idea for that training wheelset, will outlast the alu cassettes and the racing rear wheel can be fixed with the general lee adapter if you have some free mulas lying around.

 

Yes, I have one of the 38 tooth too, probably going to use it with an 11-34 cassette.

 

WRT jumps, if you look at the sprockets in the ?-36 cassettes the last jumps are 28, 32, 36, which are all 4 tooth jumps, having a 5 tooth jump is not that big (the more teeth on the sprocket, the less impact an extra tooth has on overall size and ratio as a percentage..

 

XX1 actually has a bigger jump (6 teeth) to the 42 tooth sprocket 10-12-14-16-18-21-24-28-32-36-42

[LuckyLuke]

yes that makes sense. To have the 41 over the 38 without shifting issues is definitely a bonus.

[Flowta]

yes that makes sense. To have the 41 over the 38 without shifting issues is definitely a bonus.

 

I'll test it tomorrow (rain permitting) and give you some feedback