Writing for drums, how much time should I allow for a drummer to swtch comfortably from brushes to sticks and vice versa? The tempo in this particular song is 110 BPM so one bar/measure = just over 7 seconds.
 
I know that there are double ended sticks (if that's the correct term) with brushes on one end but I have read that these are not popular with pro drummers are not of good quality. I believe that pro drummers would prefer high quality individual sticks and brushes with enough time given to change over.
 
I'd be grateful for advice on this. 
 
Thanks.

If you want an answer to that then your best bet is to learn how to play air drums. Use items, whatever you can find, that are like sticks and brushes and time yourself. Keep in mind a drummer would be a bit faster than you.

I have been playing drums for 40 years now and yes there has been many a time when one had to change from brushes to sticks (and back!) 

Well if I knew there was only going to be one change I sometimes used to put the brushes under my arms to support them there and grab the sticks from a holder that is mounted down on the high hat stand. They are great and enable you to grab the tops of the sticks easily.

Another option is to have a music stand very near your high hats set up so it is horizontal. You lay a towel on top of it and you can put quite a few things on it and they wont move around much.

You have got your timing wrong above. I beat is 60/110 which is 0.54 secs. I bar of 4/4 is only 2.18 seconds. That could be pushing it. 2 bars or just over 4 seconds is quite a long time and would enable one to put down one set of implements and gather up another and also putting the first set down OK. 

Jazz ballads sometimes go from brushes to sticks but the change over is usually at a time when the drums don't have to be involved in things so much and the rest of the ensemble might be doing a turnaround with accents or something else. Another option is to stop the music completely into silence and bring it all back in at the same time with the drummer playing something with else.

I'd say a good drummer could drop one pair and grab another from a stickholder within a beat or two. When I played super fast metal I was dropping or breaking sticks every few songs (I wasn't exactly a pro) and I'd manage to get a fresh stick in my hand before I even missed the next beat a lot of the time. If not I'd usually be back in action in on the next beat or so. I didn't even have a stick holder. My extra sticks lived on top of my bass drum between the tuning lugs and the tom stems. Swapping out BOTH sticks at once would be a bit more complicated than that but it still should only take someone with fast hands a second.

My point is I wouldn't get to worried about trying to mimic something like that if you are creating a MIDI drum track. No one's gonna notice/nitpick. If you are writing the part with the intention of having a live drummer duplicate it at some point though just ask them or leave a few seconds for the switch. Preferably on something like a downbeat. That way the drummer can make his last stick hit, drop them as he's about to make his kick hit and scoop up the new sticks before the up beat. Also on that last stick hit before the switch try to incorporate a cymbal hit (like snare and cymbal) so the cymbal ringing out covers up any gap.

...

I think I put way too much thought into that... but that's kind of a drummers mind. Making split second decisions on where your hands are gonna be at any given point in time.

Cheers.

Another way to look at it is grabbing the sticks would fall in time with the beat. Like 1, 2, 3, SWITCH, 1, 2, 3, 4.

There is no set time as each drummer has a different skill set for doing this. 

It depends on how good the drummer is on changing the sticks to brushes and visa versa. If the drummer isn't fast enough, he will need to practice it and maybe change his way of doing it.
Cj

This is interesting to me.

As a hobbiest, Id say get the song completed the way they want it first using punch ins or what ever it takes to complete the project in time first.

It will be up to the drummer to get the song down to where he/she can play it live after that.

I guess my opinion on it is, they have a song they want to record-give it to them the way they want first. Let them figure it out from there.   What else can ya do as the one recording it?    Just my opinion though

I would think that in a studio environment with a live drummer, this issue would be eliminated by simply adding another track. Layering is done all the time, so there is no real realism issue unless you are going to make a video. Even then you could edit the transition out.

Listen to non-live tunes, and you can hear these tricks all the time. Most obvious is when the vocalist overlaps his or her own singing.

I'd have to agree with Beepster...unless you're writing something they'll need to play live, I wouldn't worry about it.
If they do need to play it live then again like Beepster said " ...sticks would fall in time with the beat. Like 1, 2, 3, SWITCH, 1, 2, 3, 4."
...or if that's not enough time switch right after beat 1 and back in on the next 1.

I agree with the people here that if it's being recorded, there is no need, just overdub if you have to.
 
If it is to be played live, then it does depend on the drummer.  Over the years as a gigging and studio drummer, I've developed all sorts of techniques for doing this kind of thing.  You don't necessarily have to swap both hands at once, and can make the changeover sound instantaneous, playing with one hand as you swap the other.