Hi All,

It's been a long time I visited this forum, glad to see it's still going strong

6 years ago I build a 29er hardtail, with the help of the wealth of knowledge of people here: https://chinertown.com/index.php/topic,781.msg8546.html

It's been serving me well over the years, but a lot have changed as well. I moved from Europe to Australia. Down under I can't just leave home on MTB and enter trails 20 min later, I have to load it into car and drive 50 km to any reasonable trail network. Also, the trails themselves are way more technical than 5-10 years ago (or I'm just getting old). As a result I bought a road bike and spent way more time on tarmac recently. Still, trusty HT has never let me down on occasional fire-road trips and bikepacking adventures.

Recently, I noticed that a smal crack has appeared in hte chainstay. Was planning to rebuild it to FS for quite some time (to get more leeway on technical trails) but then realised that with standards moving on (boost everywhere) most of the parts wouldn't be compatible anyway. That's where the gravel idea appeared.

Did anyone here try that, was it successful and worth it?

My line of thinking is that:

* Wheels in HT are 15x100 front and 12x142 rear. Rear should fit most gravel frames without a problem, for the front width is ok I would just need to find fork with 15 mm axle. (There seems to be DT conversion kit for front hub going from 15 to 12, so that's an option)
* I should be able to use parts of the drivetrain (XTR M9000 rear der, cassette x01 10-42, chain) + have spare Ultegra crank laying around, which can use for the front
* I can also use current brakes (upgraded to XTR-M9000 since the original build) since all shimano road/mtb hydraulic systems are compatible
* New parts that I would need are (apart from the frameset):
    - Hydraulic mechanical road levers (7020/8020)
    - New BB
    - Tanpan to make der work with road shifters
    - PM to FM adapters for calipers
    - Front der

Am I thinking right?
What are the recommended Gravel framesets? I was looking at Winspace G2 initially ...

Now I'm regretting a little bit that I didn't wait for a new model but who would have known ... Going sub 3 pounds (around 1350g) on 29er fork is huge:
http://reviews.mtbr.com/fox-32-step-cast-fork

New options for heavier models (34,36 and 40) are also very nice

It seems that 10-42 is not wide enough and SRAM will push it further by quite a lot: http://www.thebikecomesfirst.com/possible-leaked-photos-of-new-sram-12-speed-eagle-drivetrain/

So my project has finally reached maturity. It was a lot of firsts for me, first time with hydraulic brakes, first time carbon frame and wheels, first time tubeless, first time CB not shimano pedals. I'm very happy because everything works well so far. Build list below:

Bar Ends: --
Bottle Cage: --
Bottom Bracket: Rotor BSA30+spacer 90g
Brake (Front): Formula R1 with Formula Kool Stop Pads, carbon lever 179g
Brake Disc (Front): Quaxar Axim White 160mm 72g
Brake (Rear): Formula R1 with Formula Kool Stop Pads, carbon lever 196g
Brake Disc (Rear): Quaxar Axim White 160mm 72g
Brake Bolts: 4 M6x15 Ti 10 g
Brake Disc Bolts: 6 M5x10 Ti + 6 M5x10 Al 11g
Cables: Jagwire (13) + niro housing(12-) + jagwire endcaps(3) 28g
Cassette: Sram XX1 10-42 265g
Chain: KMC X11SL with missing link 227 g
Crankset: 516 g
-Crank Arms: Sram S2200 BB30 long spindle 175mm 456g
-Chainrigns: Garbaruk Oval GXP 34T 60g
Derl (Rear):  Shimano XTR RD-M9000GS 222g
Fork: Fox Fit CTD 15mm + Fox Axle 1479+75g
Fork ekspander: In the fork weight
Frame: Carbon Speed CS-256SL 19" + Axle (Alu bottle bolts) 1039+80g
Misc: Spacer alu 5mm 3g
Grips: Extralite Hypergrips+Bar Ends 12g
Handlebar: Carbon Speed B7 680mm 119g
Headset: Nexelo 65g
Pedals: Noname eggbeater (probably 2Ti) 215 g
Seat: Carbon speed SD2  97 g
Seatpost: Carbon speed SP6 31.6/400 193 g
Seatpost clamp:  9g
Shifters: Shimano XTR SL-M9000 right 104 g
Skewers: --
Stem: Kalloy Uno -7* 70mm 91 g
Tire (Front):  Conti X-King 2.2 RaceSport 539 g
Tire (Rear): Conti X-King 2.2 Protection 647 g
Tire stuff: 229 g
Top Cap: Nexelo 16 g
Wheelset: 350s Straight pull 15mm&XX1 ThruBolt + Carbon Speed HR927C + Nipples White + Pillar TB2016 + NoTubes Tape and Duke Valves 670+788 g

Total 8358g

After bike fitting session some changes were made:

Offset noname seatpost +14g
SLR XC Gel Flow saddle +83g

Total 8455g

Will probably need a tad longer stem as well.

I achieved the weight below 8.5 kg which I was aiming for, there is still room to get it sub 8kg without ridiculous spendings.
Hope you like it, more pictures to follow.

 

I wanted to share some thoughts on the thing I've been long thinking about, something which would help me when I finally get to build my own chiner.

One can argue about superiority of one standard or another, the way I see it:

BB30/PF30

+ lower Q-factor available (no BB housing, shorter spindle)
+ often a tad lighter
+ 30 mm spindle stiffer

- creaks in the BB are very hard to get rid off, can't replace the BB housing itself (BB30)
- pressed connection less reliable in general threaded

BSA

+ threaded BB - more reliable and easily replacable
+ larger spacing between bearings - stiffer system

- only 24 mm spindle in most systems
- usually a bit heavier

I began wondering if there is a possibility of merging these two systems to have stiff and light crank with 30mm spindle and the replaceable and easy to maintain threaded BB.

It seems that some big players had the same idea recently:

Rotor
Race face

Unfortunately, these parts are priced pretty steep and I dwelled upon the idea of developing a more affordable alternative for 1x10/11 systems.

As far as I know SRAM BB30 cranks come in 2 spindle lengths:


One  can see that 6.5 mm difference in spindle length corresponds to 6.3mm difference in spacer width, so far so good.
For both BSA and BB30 (MTB) the BB shell width is 73mm. Substracting it together with the spacer width from the indicated length leaves about 13mm for DS arm installation (it could be less, that's why the 6mm wide counter ring is for).

I considered the case, let's take the long spindle version of the crank, get rid of the spacer and get rid of the counter ring. You get 101.5(spindle)+6(counter)-73(bb shell)-13(DS arm)= 21.5 mm of free space (or more if DS arm doesn't need full 13mm). Seems enough to fit the BSA30 bracket there (10.75 mm for each housing, bearings themselves are 7mm each).

In fact a guy on MTBR performed such conversion with the shorter spindle XX1 crank and narrower (old) 68mm shell:
MTBR
I asked him for clarification and he is convinced that idea above should work for a standard frame and longer spindle as well.

Two issues possible issues can occur, however both can be countered IMO:

- there is some space left and without counter ring there is sideways play in the crank (I think it can be corrected with (wave) washers, as it shouldn't be more than 2-3 mm)
- chainline could broken (this one is more complex, however from the DS point of view the ~10mm bb housing now acts as a spacer. That's less than 1mm difference compared to the spacer used in the shorter spindle. Therefore, any spiderless NW ring or spider for more 2x/3x setups designed to work with short spindle should work here as well)


That's it. Unfortunately it's just theory crafting on my part as at the moment I have no means of testing such setup. Perspective of using even BB30 x9/X0 with NW chainring on BSA frame is very tempting though.

Any input/thoughts appreciated. Of course if anybody here has a friendly LBS who would like to put this theory to the test, I'd be great.