Difference in rim Radius between 650B and 29er is 19mm , you'd have to measure how much higher is 3" tire over standard one, probably around 10mm difference, the rest will be BB height change so around 1cm of it.

The BB height from wheel centers on 29er is usually 15mm lower than on 650B. All the other height measurements would be the same if both frames are equipped with same 650B wheels. So you get the number from frame geometries only, don't need to bring wheels into it.

That means 650B frame with 650B wheels has BB 15mm higher than 29er with 650B wheels. I bet you can get 3 inch tires on both.

And the sealant in our tires dries faster.

If you pump in new sealant what do you do with the old dry one? Do you have some good fast way to clean it? Without removing, the tire would just gain weight forever..

Also how fast your sealant dries and which do you use?

Myself I also need fast gear just to have it, to use downhill or on straights. Even if you are using it 10% of time I think you would miss the gear in those 10% times like I would so keep the chainring imho.

The shifted chainline will put less stress on the big cogs but more stress on the smaller ones, so it really depends on how you use your gears and how much power you put on them. If you feel like you are using gears normally I wouldn't change the sram's specs..

Yep you are probably right, the Specialized Roubaix Zertz are almost identical:



There is supposed to be some special kind of compound inside a hole in the frame to damp any vibrations. Looked some reviews if it's a hoax or not and found only mixed answers. Some think it's really helping others say it's only for marketing. Probably bit of both.

I like the CS-041 also a lot, I dislike how the seat-stays in 256 meet into 1 piece, from some posts here I got an impression it's a weak spot. Was looking for some short chain-stay frames initially but all only fit chainrings up to 36T. This though should fit 1x11 with 38T and has nice XC geo also. Will be probably pricier also but dunno about that, should ask Peter about the price.

So Carbon Speed now has this very nice frame http://www.xmcarbonspeed.com/Productinfo.asp?f=1392:



Anyone know what the thingies in the back are? Some vibration reduce system but does it work? Does anyone seen this before?

This is also present on this road bike frame: http://www.xmcarbonspeed.com/Productinfo.asp?f=1391

Other than that the frame looks awesome.

I totally agree with MTNRCKT - to buy a carbon part from a Chinese manufacturer I basically need to know 2 things:

- Detailed specifications (geometry, what will fit to the frame and what not - what size chainrings forks and tires will fit in) - this is sometimes lacking and the website doesn't provide much.

- The quality, because my life will depend on it. I need to be sure if it's fine to go 40mph downhill and if the part will not break under braking.

This forum is great for answering both these questions from customers that pioneered and tried it. But the negative is that your sales will improve with delay after a new frame is community-tested. Because we don't know anything about the new frame and how it compares to the tested ones (manufacturing process, testing,..).

So it would help in general if:

- Specifications would be available in detail. Also I would like to know how one frame differs from another (stiffness, comfort, etc.) because usually manufacturers sell lot of models and it's hard to choose.

- The manufacturing process and the testing of the frames. It's not enough to only say T800 cabon (in better cases) and show some old testing report which no ones understands for a different part. It would be good to see the process itself.

I believe that seller offering better information will get better trust and more sales.

This is good to hear that BB92 with GXP has no issues! I live in a flat land with some hills around so I need gear ratios from 4.0 down to 1.0 as the bike will be like a cyclocross but a mtb which is stronger frame..

With 1x11 I ran into issues with frame clearance around the chainring, you are correct, so it looks like I'll use a 2x10 with 42T biggest ring which should fit. There is a thread about this from me with some frame pics.

I measure in km/h but I tried to convert to mph..

Ok just back from a ride. I need to correct the rpm I am comfortable with, its more than I said earlier: like 90 - 120 rpm and 70-90 when chilling. The speeds I travel are uphill 10km/h, flat 30-40km/h, decline or wind 40-45km/h and downhill anything upto 70km/h. I could live without the 4.0 ratio right now and maybe also without the 3.8 if I get use to pedal faster. The 36T ring I reckon I can fit.

But still I would be so happy to be able to build this mtb/cross bike, today I will devote myself on finding if there is such a frame. I'll post any findings..