ColinL

I searched and found nothing of interest, so here it goes.

I'm interested in building a monstercross bike - MTB frame with plenty of clearance for 700 x 40 - 45 mm tires, and fenders when the weather requires it. I'm talking about any given hardtail MTB frame with 68 or 73mm threaded BB shell and 135mm rear axle. Let's assume I don't care that the MTB frame is heavier than a road/CX frame, and that I can get the cockpit setup properly.

Because X9 or higher and Rival 1 / Force 1 cranks all have detachable spiders, it's currently very possible to buy 2 cranks and put the Force 1 spider on the MTB crank arms. It unfortunately doesn't appear that the 1X spider is available to sell separately - I looked in the 2015 Sram spare parts catalog, so if you believe otherwise, please post a link and/or PN. So, let's also assume that this monstercross drivetrain can be built with the MTB crank arm + Force 1 spider, giving a normal Sram MTB 1X chainline of 50 mm.

That's it, right? Well, sure, but kind of expensive to buy two cranks.... and little to no resale value in the extra road crank paired with MTB spider.

So what about the wide series cranks? They're OEM on a few gravel bikes that have 135mm rear ends, but they're all 2X (so far), and I can pretty much only find them on ebay. But what about putting a narrow-wide 110 BCD chainring (Sram Force 1, wolftooth, whatever) on the outer ring and then removing the inner ring? The chainline is 50.5 mm! (Source doc here.)

I have a feeling someone has already done this or at least thought about it.

ColinL

There's a lot of views, so I guess some of you are curious about this.

I bought a set of wide S series cranks from eBay last week and got them yesterday. Sure enough, they are the 73mm MTB spindle attached to the Force / S900 crank arms and a 110 BCD 2X spider. Absolutely perfect for a 68/73 mm frame with 135mm rear end, which is a LOT of hardtail MTB frames.

I have a 46 on there now with 11-32 ten speed cassette.The stock 50 ring cleared my seatstay but your mileage may vary. I only mention this because if you're on a 42 or smaller ring, it's easier to use a MTB crankset with 94 BCD spider, although I found the wide S series cranks to be much cheaper on eBay than Sram X0 carbon cranks or similar offerings from Raceface, etc. (Probably due to low awareness and demand.)

ColinL

All done! Test ride this morning was good, just need minor tweaking.

alex jb

Nice!
I plumped for a cheap fixie square taper type chainset and put an alloy non ramped 44t ring on as the steel one weighed a ton! I used a 113mm MTB triple BB to put the chain line out to the middle of the cassette and gives a good 8-10mm clearance to the chain stay.

Yours is a nice more modern solution.

NormanF

I had considered a 1X but I ultimately went with an IGH.

A clean look is always good to have with it a bike.

alex jb

My bamboo beast already weighs 14kg, I don't know if I would notice the extra weight of IGH or not, but I had most of the 10sp kit other than the single chain set from a previous build so that's what it got.

I will source an Alfine soon and I'd like to build it into a 650b wheel

ColinL

I don't have carbon cranks on other bikes, so I wanted to try these. The bike ended up 10.7kg / 23.7lb which is not bad for a having a suspension fork and aluminum frame.

alex jb

That's great, I'm going to look on eBay for one.

ColinL

The models you want to look for are S902 or S952 for carbon arms, or S500 / S550 for forged AL. They might say 'wide axle' or 'S series'.