KiwiB

Hi All,

Hopefully this is the right place to post...

I was recently given some Sora 8's. I was also given a spare 80's Motobecane Jubilee Sport (I just bought a fully functional one. A friend heard about it, and gave me theirs as a parts bike). The frame is in pretty bad shape, but the rest of it, including Suntor ARX front/rear derailleurs, works nicely.

The Sora's have no cabling with them - I've looked around on ebay but can't figure out what cable these would need, and if there are any good-value alternatives. Can anyone point me in the right direction?

The other piece is that I want to learn more about bikes, so I'd like to try switching out the front DT shifter for one of the Sora's as a way to teach myself. I realize that an STI upgrade is not cost-effective, and I don't intend to do the full thing - it's a learning exercise.

Sheldon Brown appears to indicate (https://sheldonbrown.com/upgrade-gears.html - look under the "Front Derailer Indexing") that there's a possibility of not needing to change a FD on a double when doing this sort of conversion. As I read it, even thought STI's are indexed in the front, there are only two positions anyway on a double, so the point is somewhat moot. What's the likelyhood that, just for the front shifter, it would be possible for the Suntour FD to work? I know there's more to it than that, but for now assume that I have the cable stops and everything else sorted out.

If this will not work, any thoughts on a compatible FD that wouldn't require a change of the crank or front rings? The larger chainring is a 52. Nervar cranks, and probably swiss BB (hence the desire to avoid changing these)

Thanks!

Andrew R Stewart 

The gear cables and casings you'll want to use are the common SIS spec ones that most every LBS has, and likely the only gear specific ones they have. Inner cable will be 1.2mm diameter and smooth surfaced (or redrawn/slick) made of either galvanized or stainless steels. The casing could be either 5mm or 4mm OD with the SIS spec uncompromisable wire winding. These casings require their own special end caps and are cut with a scissors action tool. The fitting of the casings and end caps to your older bike might be one challenge point. Proper cable routing and casing installing is but one aspect of a good shifting SIS system, but an easily screwed up one.

As to the compatibility of the front STI lever with your current crank and der only trying will tell you the answer. No charts or references are available (other then individual claims) that will describe the mix you're intending. Will the lever pull enough cable, or too much, to allow the ft der to move through the range that the crank's chain ring spacing requires is the real issue. Shimano has created a system in their index drivetrains and every component is matched with the others to achieve the performance they are known for. You could measure the rings' c-c dimension on the current cranks and then do the same with a 'current" 8 speed one and see if there's any difference. I suspect the old rings will be slightly farther apart then modern ones.

If you had campy Ergo levers things up front would be different as their lever goes through many steps (clicks) between the high and low positions. These levers can accommodate many different system parts and still work well. Andy.

KiwiB

Thanks for your response, Andy!

It sounds like I could sell the Sora's and buy a campy Ergo shifter and avoid most of the issues I would encounter with the Sora's (I assume if this was in the rear I'd need campy cassette's etc. ?)

What would I need cabling wise? Is the setup for cabling with the Campy's easier or harder?

HillRider

The only Campy Ergos that still offer the "micro click" front shifting are Chorus and Record and these are VERY pricy. Buying a front derailleur compatible with your Sora brifters would be a small fraction of the cost.

Sun Tour ARX? Wow, those came OEM on my 1985 Bridgestone 400. They were decent components but were not designed for any type if indexing.

Andrew R Stewart 

Having used Ergos since the mid 90s, of course I'll say that this is the way to go. One interesting aspect of the 8 speed Ergos is that the rear, with a compatible Campy der, shifts Campy 8 speed AND Shimano 7 speed (as both use 5mm cod spacing). You can find used 8 speed Ergos for $100+ if you wait and pay attention.

Some of my concerns about the Sora ft STI use is the non spec crank. Whether it's rings are not a compatible C_C dimension is what i tried to describe and suggest be looked for. Andy.

KiwiB

...beginners luck? Based on your feedback I jumped on ebay. Found and won a set of working Campy chorus 8 speeds for $65. No cables but it looks like they wont break the bank.


That leaves me with two options to fool with. Hillrider, I can definitely snag a front derailleur. For some reason I thought finding one to match the 52t front ring would be hard, but after more research it sounds like it won't be. which leaves the big question... which will be easier as a first project? Sora and a new FD or campy?.

KiwiB

Hmm seems I missed part of yur post Andy.

What's C_C? Cog to Cog distance?

With the potential spacing issue you mentioned it sound like the campy's might be the easier project. I'd welcome any correction if I am off base.

Thanks for the help so far guys.

Andrew R Stewart 

C-C is cog to cog center dimension. Early Campy and Shimano shared this at 5mm. Since then both have narrowed the C-C but not kept the same measurement for the same cog count. As the number of cogs get more the differences get less, but the tolerances get smaller for good shifting too. For years i ran Ergo (actually Sachs) with either 7 or 8 speed freewheels. All spaced at 5mm C-C (the Sachs version of Erogs was speced to Shimano or Sachs der, not Campy).

The early Campy 8 speed has the pointy hoods (which I like). They should be thought of as needing a rebuild before use. The "G" springs wear but are a low cost part. There's a lot on on line instructions on how to rebuild them. Andy.