I just bought a Specialized Vita, and when I got it home, found that my trusty old Delta Mega Rack won't fit on it, because the rear end on the new bike is 1.5" wider than on my old one. The mounting holes on my bike are 7" apart, as opposed to the 5.5" distance on my old Trek. Any suggestions? I don't live all that close to an LBS, so would prefer to buy online if I can swing it.

Go online to Tubus

https://www.thetouringstore.com/TUBUS...OME%20PAGE.htm

I sent Tubus an email, asking about the issue, also Planet Bike and Delta, but haven't heard back from anyone yet. Tubus is rather out of my price range, unfortunately, and am hoping to find a cheaper alternative. I know that quality costs money, but I just don't have a lot of money left over this week.

I'm not aware of racks that come in "widths" as far as mounting goes. Most bikes (that you'd put a rack on) have either 130mm or 135mm dropout spacing, so rack makers assume you can flex the rack struts enough to accommodate a few mm's more or less.
Looking at pic of the Vita online, it seems to me that the rack mount bosses at the dropout are molded as part of the seatstay socket, meaning you have to mount the rack not only outboard of the dropouts, but also outboard the seatstay, which would make it pretty wide.
I'd suggest either 1)try spreading your current rack out to fit (use a little muscle. If you break it, well, you were buying a new rack anyway ;-), or 2) if there is room inside the seatstay and clearance from the cassette gears, try mounting the rack inside the dropout, rather than outside. Using button-head bolts, rather than socket head, might help with clearance there, too.
I have 2 Topeak racks that I've mounted to pretty wide MTB frames with no problem, but I'm sure a PB or Delta rack could be made to fit as well.
Just my 2c.

-Pete

From the outside of one eyelet to the outside of the other is 175mm. Wayne from The Touring Store didn't really believe that I was measuring right, so I took a picture to show him the odd shape of my rear end (snerk).


I thought about trying to bend my old rack out, but my husband really needed one too, so once I decided I couldn't use it, I put it on his bike-- I think he'd be pretty grumpy if I took it back off his and bent the daylights out of it.

That's a funny-looking rear-end alright!
Looks like the inside-mount might work, though, with plenty of clearance.

At the risk of sounding thick, how do I decide if there's enough clearance on the drive side? I can get the small end of a L-shaped hex wrench in there, but even with a button-head bolt, it'll be really close. Or do I just have to attempt to mount it and see if it's in the way?

You should be able to safely bend the rack legs out enough to fit the new bike. I've done this with several "standard" width racks for my Santana tandem, which has 160mm OLD spacing.

I doubt you'd be able to mount it inside the dropouts without interfering with the chain, and that seems like a pretty unorthodox approach also.

I'll try bending it. More accurately, I'll try to get someone else to try bending it. I pulled at it the other day and had no luck getting it to budge. Upper body strength, I don't has it.

I might just try the inside mount first before you bother bending it.
And, yes, you pretty much just bolt the strut on there and try shifting to the smallest cog to see if there is any interference.
Not sure what "orthodox" is, but 175mm to the outside of the bosses sure isn't typical! In this case, with the spacing and unique configuration at the rear axle it almost seems like the designer intended the rack to be inside mounted. The only drawback is slightly-inconvenient access to the fastener. Luckily you don't need to take racks off that often.

are the eyelets on the seat stay or dropouts?

I expect it's the current normal 135 wide rear axle width..

bolt up one side, outside on the right , then pull the opposite side .
out with the mounting bolt,
no gears to clear over , there , it can go on the inside.