Thanks! Yes it's a boost frame with 42 chainring I think that a 44 also will fit. Size off the frame's are XL and L.

Looks like a 46 round or 44 oval will fit.

Is that 52mm Boost with +3 offset chainring?

TT918 looks interesting - aside from the stupid seatstay holes.  It has modern TT bike geo.  If Mira will sell it for their normal pricing directly, it's fairly compelling.

Pretty sure most people aren't using DUB Wide unless they have the full SRAM groupset, or are running Boost (rather than Wide) on MTB hardtails or are on one of the tiny number of gravel bikes that require it - usually bikepacking stuff like the Cutthroat.

Loads of people use Eagle with road chainline.

There are so many hardtails suitable for hardtail use.   The market is already completely saturated.  As you might see from the many posts and threads here, what people are really interested in now, and the growth market, is hardtails suitable for use as drop bar gravel bikes.

So I'd scratch the 120mm and do 100mm.

Legit 44-46T 1x clearance without an offset chainline.  Option of running an FD with up to 50-34.  If this can be achieved with 142x12 spacing, so much the better, as it increases crank and gearing options significantly.

Top tube on the slightly shorter side, to allow for additional reach from drop bars.  Maybe 15-20mm more stack than usual, as often these bikes are used for very long races or rides.

BB offset larger than usual for hardtails, given the use case.  ~70mm.

Steep seat angle to keep effective reach down for longer legged riders. 76deg.  Head angle around 68-68.5 degrees. 

Maybe consider a kinked downtube to allow more space for bottles and frame bags.  Aero shaping.  Down tube storage.

Top tube mount points.

These look great. Can I ask about sizing please, What size is frame vs what youd normally run on a MTB?

I run a L Carbon FM936, and a 58cm Cervelo Aspero. I want to build a gravel Scott scale, but don’t know if I should go XL or l. The Scale XL has the same reach as the FM936. The L is 3cm shorter.

The XL will have absolutely massive reach for a gravel drop bar bike ... unless you're enormous, or very high on the ape index, I doubt you'd be able to cope with it.

My brother and I did something similar. Mine is the pinkish one with drop bars, his is the white one with flat bars.
Not the greatest picture, but it's the only one I have of my brother's flat bar one. It was taken at the end of a 200km MTB/gravel race that turned out to be a mudfest.

We used the Airwolf YFM026 with the Airwolf fork. The Airwolf fork actually has a 480mm A-C length, which steepens the HTA a bit more, and also steepens the STA a small amount. The steep HTA is fine for gravel riding/racing (and beachracing), and we both run the saddle all the way forward on the rails with a zero setback seatpost.

Regarding the chainring size. The white bike has a 42-tooth ring on a standard boost crankset. It's the biggest you can fit without altering the chainline.

So that's 52mm boost with +3 offset fits a 42T?  Presumably 46T will fit with 0mm offset?  If I could fit a 44T oval without altering the chainline, that would be ideal.

I'm hoping the new Spark Gravel RC will have generous chainring clearance, which will push the copy cats to do the same.

Build complete

Went with size 56 I'm 182


Sram force shifters & brakes

Sram red xplr 13 speed derailleur and cassette

Enve AR 40cm bars

Mosso 90mm stem

Enve SES 4.5 wheels

tufo gravel thundero 48mm (tubeless 60ml sealant in each)

Ceramic speed T47 BB

Garbaruk gravel crankset

Garbaruk 38t chainring


Weight was 8.14 no cages pedals etc


Overall I'm happy with it. Rear brake mounts are on a slight angle took abit of work to not get it to rub. Really needs to be faced.

How's clearance?  Especially at the rear.  Will a 2.1" fit?  Will a 2.1" fit with an FD?  Thundero 48 and FD?  2.2 race king fit on the front?

I'm considering this in the 54 for a rider I'm sponsoring.  Other option is Liv Devote ... which has better geo and should have better build quality - but I'd have to swap out 80% of the kit to get the right setup for her.