Weight Weenies

Hi I'm after some help with a bike I'm building right now.

Bike is a brand new moots rsl cx frame I intend to use as a race bike but also multi purpose for road and also off road. I've previously used wide range sram 1x gearing with 48t front wn ring and an 11-36 cassette. I got used to it and loved it's simplicity. Gaps was not an issue nor was ratio.

It was lacking a bit for really steep climbs.

New build I is running di2 9170 shifters and I have an xtr rear di2 mech. This moots will be a 1x setup also.

I've found a few people who have run 10-40 xtr or sram xx 10-42 and xtr di2 mech without issue.

This setup is great for longer more off road but I'm also interested in the new 3t cassettes 9-32t. I could run a smaller front ring and tighter ratio gearing with no real downside other than price......

Question is will a 9t work with Di2 mech / shifting. Forgive me I've always run sram and Shimano is new to me......

I have a set of eastons new cranks so changing from rings for ride is fairly easy. Ideally a 40t or 42t front ring will give me good road gravel gearing and less weight.

Hopefully some one here can help?

Cheers Sam

Well, 42x9 is only a slightly smaller gear than 53x11. With gravel-appropriate tires, that's a BIGGER gear than 53x11 and typical road tires.

Don't know about you, but I'm not going to be pushing that big of a gear on gravel roads.

42x9 at 100rpm on 700x44s: 38.7mph.

53x11 at 100rpm on 700x25s: 37.8mph.



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Thanks yes you are correct. 42 or a 40 and a 9t rear is ideal roadie range. For gravel long rides I'll flip over to to 11-40.

Perhaps a 40 ring from with a 9t will give good rollout and nice tight gears still with a decent climbing gear.

Question was more along lines of knowing if 9t sprocket would have issues shifting with and an xtr di2 rear mech.

Thanks for reply.

I can't directly answer your question, but keep in mind that the new 3T cassette uses an XD driver body on the freehub.

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Thanks yep already have one fitted on my tune hubs so it is easy for me. Weight saving should be good.

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I have no tried it but there is no reason this shouldn't work. It you're not doing really hardcore gravel you could use a dura ace or ultegra mech. It would potentially shift a bit better over the smaller cassette

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