Can I Run a Compact Chainset on an Old Front Derailleur?

[macman35]

I am restoring a 1986 Peugeot Premiere 10 speed bike. Keeping it mostly original, but I would like to fit a compact chainset in place of the existing Solida 52-42T set up, and change the bottom bracket. I have found a suitable retro 50-34T chainset at SJS, but have conflicting advice as to whether this will work OK with the existing front mech, which is a Sachs-Huret AV 62.10 Avant. One person said I'd just need to lower the FD slightly, another said that a 16 tooth difference was probably too great for the Sachs Huret?
There is a 5 speed Maillard freewheel on the back, which is in good condition, as is the rear mech, so not planning to change those. I'm also retaining the original Huret downtube friction shifters.
Any advice would be welcomed-thanks.

 

[KermitGKona88]

Re:

I would say it is a no go, the problem you are going to have, is that with such a large difference at the front if you adjust the mech to just clear the large ring, the chain will be running on the bottom of the cage on the small ring.

Do you really need a ring as small as 34 on the front ?

 

[mattr]

Maybe go for something a little less gappy, most older mechs struggle with more than a 10-12 tooth gap, the side plates/mech couldn't be made stiff enough so they made them shorter. New ones are profiled to increase stiffness, so they'll shift 15/16 (or more) tooth gaps.

Something like 38 inner should work with the 50 (and yes, you'll need to lower the front mech)

 

[t47b]

Re:

I thought I would struggle with 52/42, so I fitted a 14-28 (sunrace) on the back I can get up the steepest hill on this, maybe try this approach first as an easier option?

 

[macman35]

Re:

No, it doesn't have to be 34/50T, but the chainset I was considering is only available in this spec, it has a retro look that matches the rest of the bike quite well I think.
https://www.sjscycles.co.uk/chainsets/a ... 34t-170mm/
I haven't seen anything else available as new that suits as well, but open to suggestions.
Yes I could change the freewheel to gear it down a bit, though not sure if this will need something with a French thread or not, being a Maillard from 1986. If it does, I guess this limits my options more. The existing freewheel is 14-24T.
And, if I use a 14-28T freewheel, will this work OK with the existing rear mech? This is a Sachs Huret P5, and I thought the largest cog these old derailleurs would work with is around 26T?

 

[mattr]

You could buy it and try it, if it doesn't work get a 37 or 38 tooth chainring and swap it over.

 

[macman35]

Re:

Further research tells me that the derailleur is an Eco, not a P5, and the maximum cog on this is 28. And, after cleaning it, I can see now a marking on it that says 'Dente/teeth 24 28'. There are two location holes for the cage, so it can be placed on the 24 setting or the 28. setting-strangely, it's already set on 28.
What I now plan to do is to follow the advice above and fit a a new 5 speed 14-28T freewheel. This will not quite give me the low end of a 34 chainwheel, but it will be quite close.

 

[mattr]

Try changing the inner ring on the solida as well. Some solidas i can find images of have bolted rings (others have riveted ones...... which would be far harder to change!)

Just need to know the PCD of the rings

 

[macman35]

Re:

No, it's a budget chainset, riveted only.