markk900

I have been enjoying upgrading stuff on my AO-8 lately - found a very nice Campag Triomphe crank set fairly cheap, upgraded wheels etc. I have in my meagre parts supply a perfect SunTour VGT Luxe RD that I want to use (a great match to the Sun Tour SL FD already there). Problem is, when I mount it the simplex gear levers seem to have too small a diameter and getting the derailleur to shift over the first 5 freewheel sprockets (I have a 6 speed freewheel) takes up almost the entire lever travel (ie. pointed forward parallel to the frame tube almost all the way to pointed back). Shifting works great but clearly something is not right. In addition, there is not enough lever travel to get the derailleur to shift onto the largest freewheel sprocket.

I have seen other bikes with similar levers and this RD and they seem to have sorted things out - in fact there is a gold/orange UO-8 on evilbay right now with almost exactly the same setup as I want to use. The only difference is I have early all allow simplex levers rather than the plastic and chrome ones commonly found.

Last point to note: with the simplex RD the lever works perfectly and I use perhaps 50% of the travel to shift through all 6 gears at the back; also the Sun Tour FD works perfectly with the simplex lever as well.

What am I doing wrong (with the derailleur installation)?

Mark

CampyGuy

It sounds to me like you have a cable tension problem. When the shifter is all the way forward, is their slack along the downtube? If there is you have to loosen the anchor bolt on the RD, and re-adjust it. If that's not the problem I don't think I can help.

markk900

Thanks for the suggestion - I think I have the tension correct - lever all the way forward, cable pulled reasonably tight through the adjuster at the RD, and the derailleur starts to move as soon as the lever is operated. Cable is not floppy at all.

Is there another way to check if this might be the problem? I essentially backed out the limit screws so they wouldn't mask anything and as I said the derailleur shifts well but each cog takes a big chunk of lever travel.

CampyGuy

Mmm, well it's got me stumped. I would suggest a shifter with a bigger barrel, but I know you'd rather sick with the shifters you've got. I'm sure someone else hear can be more help.

meatwad

Ive tried both set ups and if I remember correctly the simplex rear derailer required less cable pull than the suntour. IOW the simplex shifter circumfrence of the 3/4 circle part that the cable runs against and determines the amount of cable pull is too small and will not pull enough cable for the suntour.

(i would just get some downtube suntour powershifters, those plasticy simplex ones feel cheesey anyway)

top506

First set your limit screws, then disconnect the cable, run the lever all the way foreward,and re-connect the cable. This will allow all the available cable travel to be used in the useful range of movement of the RD.
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cudak888 

Try mounting a set of Huret Allvit downtube levers. They have a nice, large barrel that should give you all the cable travel required.

Oh, and they're French.

-kUrt

markk900

Thanks Kurt for the suggestion.

I did some measuring and I am pretty certain its not an installation issue, and that the barrel size is indeed the issue. To cover the complete RD movement the gap between the cable adjuster and the clamp on the RD closes by about 3/4"; checking cable movement with the total possible throw of the shifter shows the distance as being close to 3/4". Which means while I might get the RD to work it will always look wrong having to bend the shifter practically all the way over to do so.

Frankly, I will find a use for the RD somewhere else, and I don't want to change the shifters as they are one of the few unique original parts on this entry level bike (all alloy instead of alloy with plastic cover or plastic with chrome cover), so I'll leave the Simplex RD on until I score a campy NR or GS..... I am after all upgrading this bike for the fun of it!

Thanks again everyone for the suggestions!

BTW: I have really been enjoying riding this bike. As it was when I had it in the 70's, changing the wheelset out made a HUGE difference (though in the 70's I used Mavic rims and Clement tubulars, now I have 700C clinchers and Ambrosia rims). If only the brakes were as nice as my MTB brakes.....

top506

FWIW, back in the day, when Nixon was President, the first upgrade I did on my Atala was to swap out the Simplex RD with a V-GT Luxe. I kept the original Simplex levers (all metal like yours) and had no problems until I discovered barcons.
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John E

The Simplex shift lever's small capstan diameter IS the problem; been there ... done that. I have run SunTour derailleurs with Campag. shift levers as well as Simplex, and the throws were always extremely long, even with only a standard 5-speed cogset.

John E

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gear freak

this is a reply to a question posted a few years ago, no one answered it. a person had put an old suntour derailleur on a bike & the control levers would not move the derailleur to shift across 5 cogs. the suntour derailllers of that era that ran the shift cable parallel to the deformable parallelogram required quite a bit if cable movement to shift. if you check out shift levers that were made to work with say a gt, vgt & vgt luxe the take up barrels on the shift levers were larger diameter, when suntour went to running the cable diagonally through the parallelogram like with the cyclone models, so this was simply a problem of using incompatible levers & derailleur together. i have no idea where you can buy shift levers like that today. a similar problem happened when schwinns came with the stem shifters & a huret allvit rear derailleur, & getting onto a 28 tooth cog was an iffy proposition with that unit. cyclist who took up the sport after the 1970s bike boom have no idea how poor some of the 1970s equipment was.