New CarbonSpeed 27.5+/29+ Frame (CS-496)

[Carbon_Dude]

Rather than going with different wheel sizes front and rear, I'd recommend you go with 27.5" x 35-40mm rims and 2.8"-3.0" tires.  If you are wanting to buy this frame, no reason not to go for a plus tire.  If you are wanting to minimize rotating mass, 27.5+ would be a bit better for your desire to have lower rotating mass and you will have more grip than just going with 29" rear wheel.

If you are running a tubeless setup, Chupacabra 27.5+ tires, on carbon wheels with light weight hubs, I wouldn't think you would have much additional rotating mass compared to a 29"x2.4" wheel tire setup.

Given the drive side high chain stay, I would think a 34T chain ring would fit easily.

[bxcc]

I agree with Carbon_dude. Pick one or the other and go as light as you can. Especially with the wheels.

As far as 29+ or 27+, that is a tough call. I went with 29+ because I wanted a bad weather / winter bike that is a summer time rock and root eating monster truck with out being a fat bike. I already have a trail bike so there wasn't a need to make it that way. My wheels consist of the RM950C rims (50mm outer / 43mm inner widths) from Peter, Hope Pro4 boost hubs, DT Swiss Aerolite spokes, and DT Swiss Pro-lock brass nipples. The total weight was 1872 grams without tape or stems. They definitely aren't super light, but considering their size, they are far from heavy. The wheels on my singlespeed are DT Swiss aluminum rims (18mm inner), DT 350 hubs, DT Aerocomp spokes and aluminum nipples and they weight 1725g. On back to back rides, I can tell a difference between the two but I'm not sure if it's due to weight or just tire size and the massive contact patch with the ground. It's not a fat bike type of ride, and it doesn't feel heavy either, it just feels different.

What will be the main use for this bike and what type of terrain are you riding?

[MVinter]

My plan wasn't to have 29" in the rear, but 27.5+ rear and 29+ up front. I think you have to red my post once more and the arguments to use two wheelsizes. Liteville have been messing around with different wheelsizes for many years so this is nothing new...

Regarding rims: my plan is 40-50mm in both ends...

[MVinter]

Given the drive side high chain stay, I would think a 34T chain ring would fit easily.

Also with 50t cassette in combination? If I do boost the cassette I will need even bigger chainring...

[MVinter]

Anyone?

[Carbon_Dude]

I've owned a Trek 69er, similar idea, 26" rear wheel, 29" front wheel.  Seemed to work well at the time.  I see no problem with trying out a mixed wheel size.

As for your chainring, if you have a 50T rear cog, I'd think you could start with a 34T ring up front to get more top end while still having a good ratio for climbing.

[MVinter]

I have decided that I will try 29+ in both ends and see how this feels. The main reason is that I have a 6-inch trail bike with 27,5 wheels and this will be replaced with a 29+ FS when I can find a bike I like (maybe next season). Then I will have only 29er wheels except for the rear wheel on this accutal bike... Right now I have too many wheel (26, 27,5, 29) and tires (city, commuting, winther, trail, downhill) in my garage and I will narrow it down to only 29er.

Regarding chainring: I think I will follow your advice with a 34t chainring. Start with a 11-42 cassette and if this is to heavy i will boost this to 50t.

I can't decide if I should go for Sram or shimano drivetrain... Pricewise shimano is much better and the possibility to boost the cassette to 50t is also a point. Sram eagle is way out of my budget... How is the performance with Sram GX?

[Carbon_Dude]

The two differences on SRAM GX vs SRAM XX1 is weight and how smooth the shifting is.  However, XX1 is about 3 times the price.  The GX 1x11 on my Stache is fine, but it doesn't have the same feel as my XX1 stuff.

[MVinter]

I think i will go with GX or shimano XT/XTR. Thank you for good input!

[carbonazza]

Just to put some fog

• I have an XX1 crank
• An Absolute black oval ring
• An XX1 cassette (that I will replace soon by a beautiful and light Hope one that come in two parts)
• An XT M8000 rear derailleur( A jumping branch broke my XTR last week, the same way I broke my XX1 earlier)
• And use KMC X11 SL chains

You can mix things, as long as you use 11sp elements, everything runs fine.

[SportingGoods]

shifter still needs to match the RD, right?

[bxcc]

Nope. All can be mixed. Just keep everything 11 speed.

[SportingGoods]

  I'm still using... 2x9 

I might go to 1x now that 12sp offers almost the same range as my 2x9. But price is going to be very different!!

[carbonazza]

Nope. All can be mixed. Just keep everything 11 speed.

Yes and no, the shifter and the derailleur must be 11sp but from the same brand.
You can't mix SRAM and Shimano for the shifter/derailleur combination.

[SportingGoods]

You know what? Because of the current contest to win this frame I started to really look into its spec (so, yes, advertising works ).

For some reason I thought it was a pure 29+ frame but then I started to notice it shows 27.5+ as well. So, I looked at the geometry today and... I LOVE IT!! I consider this frame as a perfect replacement for my current frame (which is a regular 29"):
- Boost axle (I'd love to use a Nobby Nic in the rear, at least in the winter)
- Short chainstay (actually shorter then my current 29" frame)
- Slack head angle
- Same seat post tube size (I don't have to replace my reverb seatpost!!)
- Same weight (it's good to not take any weight penalty when switching to a new frame)

Actually, the beauty of this frame being compatible 29+ is that running it with 27.5+ will drop the BB, so that I could use an even longer travel fork, to compensate a bit (maybe 10-20 mm longer).
I've been thinking a lot about going to Full-Sus CS-M04 but that's more then 1kg added (frame is +800g, shock is +200g, probably some additional hardware). It offers Full-Sus comfort and grip but a hard tail with 2 Nobby Nic 3.0 would be plenty with a 140 mm travel fork.

So... now I really wish I win this frame 
And if I don't, I'll think again... CS-M04 or CS-496