a few months ago i wrote that i was disappointed with SRAM’s new TT shifter for their ‘force’ group. their new shifter appeared to simply be a ‘carbonization’ of existing (and ancient) endshifter design, which were originally (we are talking over 3 decades ago) never intended for aerobar or TT use at all.
anyway, a few other folks responded to that thread that the real wild designs will come in SRAM’s new ‘red’ road group. well, i have still have not seen the new ‘red’ TT shifters, but if other ‘red’ components are any indication, i think SRAM is definitely notching up the bar a bit.
an example: take a look at SRAM’s new ‘red’ all-steel cassette that apparently is lighter than DA or Record. the sheer cleverness of SRAM’s novel approach gets a tip of the hat from me: a one-piece and completely hollow cassette! now my question is, how in the heck is something like this manufactured? is each cassette individually CNC machined from a block of steel, or is it an assembly of parts?
Am I (not) seeing things, or are there actually teeth missing on those cogs?
And it looks like the inner “spline” on those cogs are reversed between the inner cog and the outer one (of course there are two more small cogs to add to the cluster). Interesting. Might be a welded assembly. I can’t imagine machining that whole things out of a single billet.
the sheer cleverness of SRAM’s novel approach gets a tip of the hat from me: a one-piece and completely hollow cassette! now my question is, how in the heck is something like this manufactured? is each cassette individually CNC machined from a block of steel, or is it an assembly of parts?
The article where you got the pictures from states:
SRAM starts with solid steel billet and then proceeds to CNC machine out the entire interior and backside of the cassette, leaving just the exterior shape behind (which naturally incorporates its OpenGlide tooth profiling).
And they state that the block, minus the three smallest cogs and lockring is 100g, so adding those I’d guess it’s close to Dura Ace at 158g.
It is probably done on a 5-axis mill; it would be complex, but definitely doable. And yes, there are teeth missing. It is called OpenGlide. It’s supposed to shift better.
thanks, but something does not add up with their explanation. i think it would be quite difficult to ‘hollow out’ the cassette as shown due to the small openings on both sides.
thanks, but something does not add up with their explanation. i think it would be quite difficult to ‘hollow out’ the cassette as shown due to the small openings on both sides.
Dude, we’ve got robots driving around on Mars right now…I think they can figure out how to hollow out a cassette
The casette part and the back plate seem to be two difefrent materials. By the looks at the seam on the back plate it may not be welded as the is no significant heat affected zone back there where we woudl be able tro see some discolouration.
If I were to guess I tink they machine a block till the rear is oipen and the teeth are on the face, this block is then heat treated or given some better strength on the teeth for wear and glide.
Once they have the front finished they put the back plate on and either weld, or shrink fit the part together and then lap or machine the face to get rid of burrs. Its a great thing though!
however it is made, if the production cassettes will each be machined from mostly one block of steel, i would venture that this will be a pretty expensive part when it gets to market …
however it is made, if the production cassettes will each be machined from mostly one block of steel, i would venture that this will be a pretty expensive part when it gets to market …
It’s hard to see just how deep the interior grooves go, but it looks like it is much less than half the diameter of the opening. This would allow for a decent size bar and tool so the interior could fairly easily be done on a conventional CNC lathe with lightly modified tooling. The teeth on the other hand would take a 4 Axis CNC mill.
If I had to take a a WAG at how they are doing it or at least how I’d do it.
From a solid Billet that was 1/2" or so longer than over all part.
Turn 1/2" OD.
Turn part around, Chuck on recently turned OD.
Rough Turn OD to contour of OD of teeth. Bore and finish ID including opposite hole and groove.
Place part in Mill chucking again on extra 1/2" in 4th axis. Mill part, probably using conventional tooling to mill area between teeth and ball nose to contour teeth.
Remove part cut off excess 1/2"…voila finished part sans some of the interior stuff.
Of course you have some heat treating to do. I’d doubt that the teeth would move to much if you chose a proper material and had a decent heat treater so you may be able to do HT’ing as the final step…not sure though.
Off the top of my head if I had to make one of these it would probably cost 5-7K…if anyone is interested :-). Of course that manufacturing costs only. Not designing, R&D etc etc. If anyone wants to place an order for 2-3 thousand parts I could make them alot cheaper.
Is there a forthcoming “Red” TT shifter? Since their website indicates the current offering is, “…Compatible with SRAM Red, Force, and Rival derailleurs…,” are they, indeed, looking to offer a second alternative?
someone on another thread suggested that there will be. i sure hope that there will.
because if the current sram tt shifter is all they will be offering, i think it is a pretty weak design for what could’ve been a very innovative upgrade …
My main question is that with such a small contact surface with the free hub body I’d imagine that it would tear an aluminum body to shreds.
i thought so too at first. but anyone that has examined normal cassettes knows that many of the cogs are ‘loose’ and many of them carry their loads individually, but yet don’t seem to harm aluminum cassette bodies too bad.
since you load only one cog at a time (with the chain), in this case the whole cassette would distribute the load of an idividual cog position at two points instead of just one, so i would imagine it would be fine, if the thickness of the ‘front plate’ and ‘back plate’ are thick enough.
someone on another thread suggested that there will be. i sure hope that there will.
because if the current sram tt shifter is all they will be offering, i think it is a pretty weak design for what could’ve been a very innovative upgrade …
What’s wrong with the design? It works just fine, it’s a TT shirfter. Why reinvent the wheel. They made something different years ago, people stoped using it infavor of bar end shifters.
hmm, good point, never thought about that, guess the cogs in a normal cassette are isolated from each other… I’ve just seen some pretty brutalized hub bodies before, I guess the SRAM system would actually be an improvement thinking of it in that light
