SilverSteve

I picked up an old Mercier for cheap and I'd like to upgrade the original steel wheels with alloy rims. The brakes work better with alloy rims in the rain. Can the generic 27" wheels the bike shop sells use the same 5 speed cog set on the old steel wheel? I know that English threads are more common than French threads on wheels sold at bike shops. Thanks for your help.

Prefer alloy wheels over steel originals..

Chombi1 

Yup, good to watch out for possible French threading on components, coming from a 70's French bike.....
Holy Cow! That head tube looks mighty steep!!

TenGrainBread 

Very cool Mercier.

I would expect the freewheel threads on your current hub to be French thread. Your bike shop can pull the freewheel and check. If that is the case, it won't work with a new bike shop wheel, but a new English thread Shimano freewheel should be pretty cheap and will work fine with your derailleur.

Another cheap option is find a decent alloy wheelset at a bike coop.

If you were willing to spend a bit more you could have the shop relace your hubs to a new 700c rim, or do it yourself. That would open up your tire options. Your frame might not be a top-end race frame but it is quite nice and I think deserves an upgrade.

non-fixie 

Congrats on the find! Looks to be in great shape, too. I think those American market Merciers with their chrome socks are really pretty. So pretty in fact that I bought one a couple of years ago from a fellow forum member and had it shipped from Canada to Europe. I upgraded some parts and it has served as mrs non-fixie's main ride for the past couple of years:

Aubergine 

rustystrings61 

I have a similar Mercier (maybe a model 200?) that came to me in rattle-can blue that was one of my entries in the '17 Clunker Challenge. I enjoyed it a great deal, actually, and yours looks pretty much box stock, complete with what appears to be a T.A. cage and bottle. I think it will be a lot of fun. The generic Mercier Luxtub tubing is another example of the old saw about the French having a way with gaspipe, and if you gently rub some oil all over those Delrin Simplex derailleurs you'll help them be less brittle. If the front is broken, leave it in place and oil it up and leave well enough alone.

While you could lace up new 700C rims, if you found a screaming deal on 27-in wheels, that would not be a bad choice. For general riding around, Kenda 27 inch tires are fine, and Panaracer Pasela 27 x 1 1/4 at 70 psi is a smooth and cushy ride that does a lot of things very well. Lots of folks will chime in with the received wisdom that there are more tire choices in 700C, which is true - but how many of those choices are really useful for a non-competitive bike? If you're not out to race, or do anything extreme or awesome, duuuude, 27 is a fine wheel size that works well with classical bike boom machinery.

Salamandrine 

Several ways to go:

A) The most elegant solution is to relace the original hubs onto new rims. That way you can use your original freewheel and everything else. If you are mechanically inclined and patient, you most likely can do it yourself. DIY is obviously the cheap way to go. If you have to pay to have it done, it may not be worth it. I'd pick Sun M13 rims because they look like old Rigida 1320s, but they are stronger. Or look at the slightly pricier H+Son TB14 if you want the Mavic look.

B) New generic replacement wheels. These most likely will be 126 OLD 6/7 speed sized. Some of these are amazing deals. Cheaper than having a shop rebuild the wheels, but there are extra costs that could make it kind of a wash. The frame would need to be reset and realigned, and you would need to purchase a new freewheel and chain.

C) New wheels as above but have the shop chop the axle 6mm and chop or remove 6mm of spacer. Then redish the rear wheel. Then find a used or NOS or new BSC 5 speed freewheel somewhere, and you'd still need a new chain.

Lastly, if the brakes still have 4mm of room left in the slots to move the pads downward, you could run 700c instead of 27, and increase your rim and tire choices.

non-fixie 

+1 on the 27" with Paselas suggestion. They are my go-to tire and I haven't been disappointed yet. Actually, my own hi-ten Mercier wears them. It's a later European model, which means less chrome, but standard aluminum rims. I kept the steel cranks, BTW, and really like them.

fietsbob

as an export bike they may have used a standard british thread hub.. ..

besides if you are riding it freewheels and chains need replacement anyhow....

let the shop sort out the details ..