Spent grains bagels - Didn't turn out as good as expected

So I gave this a try. 

Been making Montreal style bagels for a couple of years now with great results following this recipe

http://www.thefreshloaf.com/node/13104/montral-style-bagels

I kept the same recipe and replaced 10% of the flour with spent grain (dehyrated and processed in a spice grinder). 

I noticed the dough wasn't as elastic, bagels didn't rise at all. So they are kind of flat (and ugly), dense, dry and crumbly. Taste is there, but texture really isn't. I guess gluten network is not what it should be. 

I was thinking of a few options and could use some input:

- Simplest option: Reduce spent grain ratio to 5%

- Let bagels rise 

- Autolyse flour and/or spent grain

- Leaven the spent grain maybe?

- More hydration? (not sure of general guidelines for spent grain in general, I thought they would require less water, but I could be wrong as it's a wild guess)

Was my first attempt of baking anything with spent grain.