el gringo

I have a 1985 Romic road bike that I want to update the wheel set on from 27" to 700C. My 27" rear wheel has a 6 speed freewheel, I have a 700C rear wheel that I want to use, it's set up for a 10 speed cassette. The drivetrain is all Shimano 600. The rear fork spread is 125mm and the O.L.D. on the new wheel is 130mm, I've adjusted the spread and don't have any problem there. My question is, will my Shimano 600 rear derailleur work with the 10 speed cassette assuming that I get the chain to match? The shifters are friction, down tube mounted in case that makes a difference, I already have extended reach brakes ordered.

Bill Kapaun

I recommend aligning the fork ends to make sure they are parallel.
Too much of an angle and they want to bend the axle slightly when clamping.

I don't have any experience with your specific RDER-
It "probably" has enough travel to span the cassette. (maybe not)
Is that travel "centered" under the cassette?
You really don't want to have to bend the RDER over to reach one end or the other of the cassette.
Maybe some careful measurements with the limit screws backed out.....

BoraxKid

In my experience, those old downtube shifters might not work so well in friction mode for a 9/10 speed drivetrain. I had a 1991 Fuji Roubaix that I refurbished from just a frame & fork to a fully-functional road bike. Along the way, I added a modern, 9-speed 105 drivetrain, but the NOS downtube friction shifter I tried to pair it with kept ghost-shifting under high efforts, even at the max friction setting. After a lot of consternation and anguish, I realized that the tolerances for a 9-speed drivetrain are probably too tight for the specs of the 7-speed friction shifter I was using. I ended up ordering a pair of indexed 9-speed downtube shifters (Dura-Ace, marketed as bar-end options for TT bikes) and mounting those. Everything went better than expected, and I never had another issue with shifting.

Once you check the rear dropouts for alignment, make sure you have a good chainline from your crankset to the cassette. Another source of frustration during my build-up of the Roubaix was getting the correct amount of spacers on the drive-side of the bottom bracket. At first, if I was in the small ring and using any of the smallest 4-5 cogs on the cassette, I would hear the chain rubbing the big ring. I think I had to re-mount the bottom bracket 3 times in total, but I eventually got the spacers right. That build was a learning experience, if nothing else!

Homebrew01

I have a similar setup on 1 of my bikes, using an old Suntour Cyclone RD. I could just barely reach the largest cog. To improve it, I filed down the "L" tab that the limit screw hits a little bit, to give a tiny bit more travel.

zacster

I've done 3 bikes with friction shifters and 10sp wheels and they've all worked just fine, and better than you'd think. The first was a Campy NR downtube shifters and derailleurs and this worked from the first time I tried it. The issue with this one is that the derailleur hits the spokes on the largest cog. The hanger might be bent but the old Campy doesn't use the same thread as the current bikes do in the hanger. I set the limit so the largest cog is locked out. The second was Campy SR friction and this one will work with all 10 cogs. The third is Suntour with friction/indexed downtube shifters. All use Campy 10sp cassettes. I've used Campy, Shimano and KMC chains. I think the Shimano chain is 9sp but it works on the Campy cassette.

The thing with all of these is that the shifting itself is very smooth and quiet. The ramps on the cassette plus the narrow chain make it all happen much quicker than on the old 6 speed. There is no clink, clink, clink when you are between gears, a light touch of the shifter will make the shift. A 6 speed cassette is almost the same width as a Campy 10 and Shimano 10 isn't that much different. You should have enough movement of the derailleur and shifter to go through all the cogs.

You'll have a bigger issue with going from 27" to 700c than with the shifting. You have to have brake calipers that can reach and not all do. If they don't they can always be replaced, and I like Tektro dual pivots for that. They are inexpensive and they work much better than the old single pivot side pulls ever did even if they aren't as good as current Shimano or Campy.

el gringo

Thanks zacster. I already have a set of Shimano long reach brakes ordered, the brakes on my bike are 47mm reach and I need about 50mm to be safe. I think that I'm going to order a 10 speed cassette and chain and go from there. I really appreciate your input.