I started laughing as soon as I read the word Valentino....

Tullio truly hated his son Valentino!

Getting back to [MENTION=52458]jonwvara[/MENTION] Peugeot used 14-28T FWs and 52-36T chainrings on some U0-8s in the 70's (others were 52-40T). Simplex Prestige derailleurs worked fine with those combinations (when new, well adjusted and lubed, including cables and chain).

The Alpine gearing that was the most common set up on lower end bikes during the early 70's bike boom used 5 speed 14-28T FWs with 52-36T, 52-40T or 52-42T chain rings.

We frequently set those bikes up with 14-32T freewheels. That was 34T which is the published limit for standard Simplex Prestige RDs.


There are 2 different specifications for derailleur capacities:

One is the largest size freewheel sprocket that a derailleur will work with. The other relates to how much chain the derailleur can wrap up.

Formula for Second spec: Number of teeth difference between the smallest and largest Freewheel sprocket plus the difference between the small and large chainrings teeth.

For example: Freewheel, 28 -14 = 14 Teeth. Chain rings, 52 -42 = 10 Teeth. 14T +10T = 24T


The Simplex AR 637 NI/P is a direct mount derailleur for attaching directly to a dropout with an integral hanger. The /P indicated that the derailleur came with a detachable claw hanger. These were not very common.

Millions of standard Simplex AR 637 P derailleurs were produced from the mid 60's until the mid 70's. They had an integral claw hanger. See parts breakdown below.




Velobase.com is a great resource, much like Wikipedia, but information can be posted by anyone so those sites shouldn't be taken as gospel, just reference points.

The derailleur described as a Simplex AR 637 NI/P is WRONG.... It's a standard AR 637 P... (I'll contact the webmaster and get it corrected)


Clear as mud eh?


Simplex produced the Maxi Prestige ref AR 642 with a long pulley cage and a long claw hanger attachment. They were uncommon. I've only seen a few of them and that was back in the early 70's.



The 1972 Simplex catalog lists the capacity as 13 e 30 dents meaning 30T large sprocket. Sutherland's lists 36T maximum freewheel size and 39T chain wrap capacity.


Back in the 60's the French used granny gears on the chainrings on a lot of touring bikes. A double might have a 48T to 50T large chainring with a 26T small ring. Triples had 1/2 step gearing with a granny gear, for example 50-47-26.


Both the Simplex Maxi Prestige and the Huret Super Alvit long arm derailleurs worked best with a large difference in the number of chainring teeth and a small differenc on the freewheel - like a 13-24T or 13-26T FW.

They could handle large freewheel sprockets but never shifted very well. By the early 70's Suntour ate their lunch with inexpensive long arm derailleurs that actually WORKED with zero futzing!


So, a standard Simplex Prestige will work OK especially if you are trying to keep your bike original.


BITD in the day Simplex derailleurs were so cheap that if we couldn't get one working right within 5 minutes on a repair job, we just chucked it and put a new one on the bike for under $10 including a new cable and labor!


I never thought that I'd EVER spend good money on a Delrin bodied Simplex derailleur but I've bought 2 or 3 better quality Criteriums for my my classic French bikes!

verktyg

Chas.