One of the Roubo components I was most weary of before I built one was the crochet. One would think the leg vise would be enough to anchor long horizontal pieces when planing edges. Would an installed crochet stick out too much and get in the way?
During the design phase, I went for a removable crochet. Unlike the large traditional crochet (e.g. this one shown in a video by Steve Branam), I had opted for a simple dowel that slots into a hole just in front of the planing stop. Maybe this is not technically a crochet as it does not hook around the work, but more of a horizontal planing-stop.
Looking back, I now see the inclusion of the stop as an almost critical element of the bench. Many times, the clamping power of the vise alone is not adequate to prevent movement of a large piece during planing.
The main advantage of a traditional crochet, however, is that work can be wedged into it so there is less need for a leg vise at all.
T r i a l & E r r o r 
Don’t you know it’s too d****d cold to have the shop door open. (11°F here last night)
No crochet needed on my English bench. The apron is full of dog holes letting me put holdfasts anywhere. Boatbuilding, the original use for the bench, has lots and lots of edge work.
Keep havin’ fun!
Ha – this is Houston where the unseasonably cold weather can still be tackled in a t-shirt!
I never find the crochet on my roubo to be in the way. I use it 95% of the times I use the leg vise.
Very good idea to add a dowel in front of the leg vise. I will add this to my bench next weekend. Simple to add…
I’m glad you find it useful!