Troul 

May I please receive some help to finding out if a 68x110mm bottom bracket will allow a stock triple crank set to clear the drive side area ensuring it will not hit anything on a trek 8.3DS? Chances are, if it clears the drive side, the nds will be fine. If a year for the trek should make any difference, 2012 is the model year.
Stock BB is a 68x122.5 from what I remember.

Another option that might help is if you have a stock triple chain ring set & could measure from the most *rearward facing* tooth on each chain ring to the nearest area having the least amount of gap.

hokiefyd 

I can't help specifically on a Trek DS and without knowing your crankset, but I just did something very similar on my Roam. I wanted the crankset a little further inboard for better chainline. I recently found a bike parts deal locally where someone upgraded his bike to Sora, and was selling an Alivio RD, an Acera FD, and FSA crankset, and an FSA/RPM bottom bracket. The BB is about 110 or so, down from the stock length of 122, so it's very similar to what you just did. The only thing I installed on my Roam was the bottom bracket; I'm using the rest of the parts on a different bike.

With the narrower BB, there's just not QUITE enough adjustment on the front derailer for the chain to not rub when in low/low. With the limiting screw all the way out (and the cable undone), there was a slight rub, which I was able to mostly tune out by slightly turning the FD on the frame a degree or two so the rear of the cage rotated in towards the tire. The alignment of the cage and the chain rings actually looks pretty good, so it may have actually been rotated out a little too far prior. There's still a VERY slight drag in low/low, but not really audible when on the bike actually riding it. And I'm very rarely in low/low anyway, so I'm satisifed. Chainline is much better. It used to be that the small chainring lined up with the 5th of 9 sprockets, which is pretty bad in my opinion. Low/low was a pretty bad crosschain before, and the middle ring and low gear on the back was really bad. It's much better now -- small chainring and 3rd sprocket gives a straight chain, which is nice.

I know you're concerned about frame clearance (valid concern), but think about derailer adjustability and chainline also.

Doctor Morbius

I believe the Trek 8.3 DS has a "trekking" triple chainring of 48/38/28. If that's the case, a 110 is probably going to be too narrow. It may work without the granny gear, but even then I think it's going to be too snug of a fit.

And it is the crankset that determines the bottom bracket spindle length so I doubt there's more than a couple of mm to play with.

I have 2 hybrids that came stock with a 68x122.5 square taper BB and 48/38/28. One of them is still stock, but when i decided to make the other hybrid a 1x I used a different BB that matched the crankset I put on the bike.

Troul 

That is what I have noticed & setting the cable tension is always a need when replacing corresponding parts. If I brought the crank inboard more, it might never need to be trimmed or heavily fine tuned is what I am thinking.

Recently I installed a front road der that was not playing nice to reach all three rings. At first I thought it was just an incompatibility issue, & as I have always noticed the front rings to rear cogs just seemed oddly positioned this raised my inquiry to see what the gap is.
The brifter ended up having something going on it its inner workings that I ended up replacing that one brifter. All is well now, but when it comes time to replace the BB, I'll trying experimenting with the spacing. Maybe not a 110, but something less then the one it has now.


Thank you for the input!

TakingMyTime

Why don't you try a 118mm? That would shorten it by 2mm on each side. I can't say for sure you won't have any problems, but I kind of doubt you would. Besides, you can get a new Shimano UN55 for $15 and if it doesn't do the job you're not out that much.