Compact crankset on a vintage?
 

Hi all,
I've got a late-eighties road bike running Suntour Sprint 9000. I'm more than happy with it on flat(ish) terrain, but there are a lot of hills around here bigger than I can tackle with the current setup. I've noticed you can pick up a new Campy Mirage compact crankset for next to nix on ebay. Does anyone know if this would be compatible with my current setup? I don't know what sort of bb I've got, except that it works with the Suntour crankset.
Note that I don't want to do anything too radical as I'd like to be able to put the Suntour gear back on when I don't need the low gears.
Any help/advice gratefully appreciated.

I am not sure a 10 speed crank would work very well with the rest of your components. I would recommend you look at a Sugino XD500. It will be compatible with your existing bottom bracket and look more appropriate for a vintage bike.

I have a '80 Fuji Finest that had 53/44 chainrings and I replaced that with a 50/38 set that I had in my parts bin, works great. I am running 7 speed freewheel.

Most of those Mirage compacts on the Bay are 9 speed, so an 8 speed chain should work just fine. With Ergo's you would need a front derailluer that is for a comapct crank. I don't know that you would with friction, but it's possible.

I put a Veloce 50/34 on my 69 Comp, but I needed a long cage RD, so went with the matching Veloce RD also. Six speed SIS Shimano freewheel. 8 speed chain. Some old campy FD. Works like a charm. In hindsight, I probably could have got by with a med cage, but I wnated to keep the option open to go 34T in back.

I just put a Centaur 10 speed compact on my 1980 Woodrup, but with a 9-speed chain. There is a little chain rub when in the small chainwheel. Branford bike site says there are some spacers I can get that will slightly widen the distance between the chainwheels and set up the correct clearance for retrofitting.

I haven't tried it yet, but I plan to.

Regarding front derailleurs, I previously had a Campy Triple on this bike, with their old Racing Triple front derailleur. I've kept it, but I might go to a new Campy derailleur that is designed for compact, if I can find one cheap enough and that fits a vintage seat tube. Or maybe FSA?

I just took chain rings off a donor mountain bike, and "created" a compact crankset for my Lotus. It came with a 52/42 as I recall, it now has a 47/36.

I must say that the half step was used in the days of 5 speed freewheels (that I am still riding)hehe.......It gave us a full ten gear ratios rather than 6 or 7 distinctive gears. With todays 8,9,10, and even 11 cog hubs the real need for half step has pretty much evaporated. I don't really see the need for half step today. If one is using a really wide ratio cassette like a 11-34 the half step might be of bennefit. 3 chain rings were rare back then as well. I really like the 3 chain rings here in the hills of TN. Good luck with your project and I wish you well. Let us know how the half step works out.

It can be done. Note that you might need to change out bottom brackets (depends on the crankset), and that if you're using indexed shifting, the shifters need to be compatible with the cassette on the rear. I have an '84 Trek set up as a "hot-rod" with a compact crankset. It will be a lot more enjoyable when I get a properly functioning 9 speed rear derailleur. :o

The problem is that your Suntour might be JIS taper, while the temptingly inexpensive compact Campy cranks on Ebay are ISO. I wouldn't recommend frequent crank switches with that issue. But then again, my 80's Japanese Sugino crank is ISO, so just maybe Suntour also went that route? A question for the experts.

FWIW, I got a 10 speed Veloce compact (with Veloce sealed bearing BB) that shows no incompatibility quirks with an 8 speed chain, an old Maillard freewheel and Mavic derailleurs. I did change the inner ring from 34 to 36. The derailleurs are standard road components from the 6 speed era, short cage etc, but they handle the 50t-36t front 12t-24t rear range fine. Any more would be tricky. This is all with friction shifting.

Jan

I will have a similar setup on my Paramount: Veloce compact with 5-speed freewheel, Campy derailleurs with friction shifting. I believe my bb is Chorus at 102mm. Rear is just 13-21.

I picked one of these up on the 'bay and put the rings on the original crank on my 1980's Fuji. This should maintain the original spacing with no BB issues.

I'd go for the CT crank and try it with your current setup. A Veloce BB is a cheap addition if it turns out you need it. I did this with my wife's 86 Bianchi that's running late 80's friction Athena FD and Chorus RD and it works great.

I'm pretty sure the BB that Campy meant for this is the AC-H in 111 mm width. It would be this same width for both English or Italian BB shells. It was intended for Veloce and the other mid to lower gruppos. Should fit the same as an AC-S, just taht the AC-S will be a lot heaver since it has a solid crank axle. These are all sealed BBs. I've had an AC-H in the Woodrup for about three years, no problems, and I have had another one in another bike. I got that one from a CR lister for $10, and another new on final markdown for around $20. Nowhere near as light as a recent carbon-shell Record, but it works great. On Ebay you might also find a Token or IRD BB to the same spec, that should work right and have good longevity. I wouldn't mess with making a cup and cone design, even a Campy, work. Nothing wrong with them, it's just a whole added dimension of compatibility issues to work through.

Road Fan

Thanks for all the great advice. Plenty to think about. I'd originally thought I'd put smaller rings on the existing crank, but I haven't been able to find any with the right bcd. Sounds like there's a good enough chance of success to give it a try with the compact.
Of course, I could just get stronger legs ;-)

I would not try a Campy crank with a potentially non-compatible square-taper. If the taper is too narrow, the crank arms will seat (if they seat!) too close to the bike centerline, messing up the chainline. If the taper is too wide, the crank arms will seat too far from the centerline, messing up the chainline in the opposite direction. If the square end is about the same size as Campy but the wrong taper, the stress pattern inside the Campy crank arms will not be as intended when its torqued. I can't say what problem would manifest itself due to that improper pattern, but I could imagine crack formation and eventual fracture of the crank arm.

If a correct BB is available for up to say $40, I'd go for it. You'd spend at least another $40 rectifying the results of a fractured crank, and have down time. It may be a low-probablility problem or not, but I dont' like looking over my shoulder at things like that.

I guess Campy never brought those replacement muscles to market, huh?

Incidentally I'm also going to stick on a big freewheel and my spare Deore rd. Aesthetically, of course, it's going to be UGLY, which is part of the reason I want to be able to put the original parts back after I've conquered the hills.

I currently run 47/38 on Capo #1, using a quasi-standard (128mm instead of 130mm BCD) road crankset.

I still love half-step and use it on the UO-8 (45-42/13-15-17-20-23-26) and Capo #2 (49-46/14-16-18-21-24-26), but most late model spiders put the rings so far apart that the chain falls between the teeth.

Hello. I think you can help me. I have an old Mangusta 5000 (mongoose made it) and I am having the same problem the guy you gave advice it is. I am literally being passed by elderly women on hills.

I had a bike shop replace my freewheel from 25 to 28 and it helped. Not a lot but it did. I have a Shimano FC-1050 crank, and a Shimano rd-1050. The crank is 52/42. The only 6-speed I can find is Sunrace FC-R31 which is 53/39. To do a 50/34 do I need a new DR? If so, can you help me find the right kind? Or at least point me in the right direction? Many thanks.

Maybe something like this?

That poster hasn't logged in in almost 10 years.

Sort of the price of bumping a dead thread.

Chances are, if you start a new thread- you'll get some excellent answers from people that have done this.

IMO- you don't need to use new, modern swoopy looking components on an old bike to get the desired gearing. Lots of old (and inexpensive, but very cool) MTB/ATB derailleurs will suit your needs better and suit your bike better.

Good luck!