Bicycle Mechanics - Upgrading my 14 speed peugeot...

Ok I have a great shape 89' 14 speed peugeot triathlon bike

I recently wrecked my wheels (Velotech by Mavic with shimano 105 hubs) and cannot find ones like it so i went out and bought a set of American classic 420 Aero wheels.

Instead of keeping with the 7-speed cassette, i was thinking of upgrading to a 8 or 9-speed and buying what i need to upgrade if it isn't too much. I wanted to stick with Shimano 105 and don't mind buying used to save on the $$. Plus my bike also runs downtube shifters and want to keep it as a downtube shifting bike. I would only need to buy one shifter because it would only affect my rear derailleur. So to my understanding this should be right other than buying a new cable

8/9 speed downtube shifter (i would like to find a shimano one)
8/9 speed shimano 105 rear derailleur
8/9 speed cassette

is this correct on what i would need?

ps. yes i know there is an axle size difference and i am fine with spreading the rear forks wider to support my new wheelset.

Will need to replace the chain (no big deal). Existing RD may handle it (worth a try).

This would be a good time to consider STI. You can find brand new nine speed Dura Ace levers at Chain Reaction Cycles, or step up to nine speed STI.

Cheapest route is to find a donor bike. A good donor can supply all components, wheelset (you don't need those), everything. For example, I have a 1995 Fuji Roubaix, 8 speed Shimano 105 with STI. It will be going on my 1992 Paramount. Then lesser components will go on the Roubaix, and it will move on to a new home. I bought the Fuji right, so this upgrade of my Paramount will be very affordable.

Why do you want 8 or 9 speeds ?

Yeah that looks good. You should be fine.

just want more gears in between for slopes and a nice flat gear for some speed, I have a 27-13T sproket on it right now and would like to go about 28-11T or 28-12T

I kinda want to keep the downtube shifters as a sign of kinda keeping it classic in its time

as far as my cassette can i go with any? as long as the speeds match? or do i have to get a dura ace cassette if i have dura ace derailleur?

I wanted to stick with Shimano 105 You maybe able to use a Deore XT 7 speed 12-28 cassette ?

I would run friction shifters if it was my bike you can get a set for 38.00 bucks.And a 11-32 cassette.

Curious--for anyone who's done this stuff. I mainly ride/maintain vintage steel bikes. Never upgraded to anything too new--what kind of weight difference is there between 80s 6- or 7-speed components and newer, STI 8/9-speed stuff? Are newer components lighter in sum than the older stuff or heavier? Or is the difference negligible?

The read dropout spreading 126>130, and getting it aligned accurately, again,
when you are done, is the main challenge.

as the new 'speeds' are added .. the parts and all the spares cost a Lot More.

Curious--for anyone who's done this stuff. I mainly ride/maintain vintage steel bikes. Never upgraded to anything too new--what kind of weight difference is there between 80s 6- or 7-speed components and newer, STI 8/9-speed stuff? Are newer components lighter in sum than the older stuff or heavier? Or is the difference negligible?

Depends on the grades of components in my experience, and particularly the wheels. Realize that brifters will weigh more than DT levers, but the remaining parts will be lighter. I am always amazed how light high end vintage steel bikes can be, having grown up with the heavy, EF Schwinns. I didn't realize back then that there were some pretty sweet bikes out there. Of course, I couldn't have afforded them anyway.

454 grams = one pound. Wide variation on wheel weights.

My 1984 steel frame Lotus Classique weighed within a half pound of my 2005 Trek 1000 (aluminum frame, carbon fork, etc).

I usually upgrade for riding comfort (I just like STI), rather than any weight savings. I've got three bikes in the upgrade queue right now. Will be interesting to see what if any weight savings result. But all of them came with pretty good stuff originally, so I am not expecting a lot of savings.