How happy are you with the Pasela 27"? That's probably the best tire available in that size these days. It's readily available, but if you're looking for performance on a par with a Compass EL you won't find it in 630. But the Trek 720 is a very sweet frame and I think you would feel the difference.

If you're going to spread the rear triangle to 130 and build a new wheel on a 9 speed hub, why not go all the way and get new rims in 622 rather than 630? You'll find more choices in rims in that size too.

This is the problem with the Helicomatic hub, there is no super-easy way to convert to normal stuff other than to find a different suitable rear wheel. And rear wheels turn out to be just about the first major part of an old bike to get whacked out of shape, so good replacements are not so common to find on the cheap.

Which is why I suggested rebuilding the original rim (assumed to be in good condition) onto a different desired hub.

I replaced the Helicomatic hub and used those wheels on my Trek 400 Elance. So I’m using the whole stock Maillard 700/Matrix front wheel, and tried my first wheel build using a Maillard 600 sealed bearing hub with the Matrix Safari rim. I failed a few times and had the LBS bail me out. (The expensive route)

If you want to go 700c or stay at 27”, It depends on what brakes you’re planning on and as [MENTION=460163]palincss[/MENTION] mentioned what you’re wanting to do for tires.

I was running EVERYTHING at 27”, and didn’t have a problem with it. Paselas and Sand Canyons were fine for me. Then I tried a Compass tire. Suddenly, I’m wanting to change out all my bikes to 700c.

Remember that going from 27” to 700c is a little more difficult on old canti framed tourers- the distance between canti studs (on the front) is much smaller than they are these days... or even by the late 80s. That means not all cantis will work. (Don’t plan on using Tektro 720s.)

Even better, keep bugging Jan to make a Compass 32-630. If enough people ask, he would probably do it. I'd buy a pair for my old Paramount.

If you wanna be niche- be NICHE! 630 in either/and 35 or 38!!!



I’m not kidding.

I used to have a set of 27” Specialized Touring/Expedition tires (Touring at 1 1/4” and Expedition at 1 3/8.”). I like to say they were like riding on soft, cushy, puffy clouds. Unfortunately, they were old and dried out- so they were soft, cushy, puffy clouds that could violently explode with no warning.

I do like the Sand Canyon gum/tan wall tires- I’d get a set of the higher TPI tires, but I don’t want black walls.

I used the Specialized Touring tires for years on my Paramount, and I had a set of the Expeditions on my tandem once. They were great tires for their day. But that Expedition was the only 27 x 1 3/8" tire I ever saw back then, and these days there is no directly equivalent tire, never mind one better.

I have experienced that the Sand Canyon 1 3/8” tire is bigger and wider than the Pasela 1 1/4” unlike some people.

I would guess that the Expedition would roughly correlate to the 120 TPI Sand Canyon.

So, I've located a set of 9 speed, 700c replacement wheels which slip right in, no cold setting required.

As part of the overhaul process I pulled out the bb and am considering upgrading with a phil wood. The original bb has a 121.5mm spindle. Now that I'm going with a wider wheel does that need to change or will original length continue to work?

You only need to correct for chainline if your cassette spacing has moved net outboard or inboard more than a mm or two. Campagnolo's chainline spec has not changed since about 1960, despite going from 5 to 11 rear cogs

So, are you taking about the space between gears? I'm going from a helicomatic 6 speed cassette to a Shimano 9 speed. Obviously, completely different wheels as well.

Helicomatic repurposing.

No, I'm talking about the total width of the cassette. Sorry, I phrased that badly I guess.

Chainline is the distance from the centerline of the bike to the centerline of the front and rear driveline components. That distance should be the same front and rear.
In the front, the center of the center ring on a triple is the measurement point. On a double, it's the middle of the chainring gap. On a single, well, you get it.
In the rear, the center of the total width of the cogset is the measurement point. Sometimes there's a cog there, sometimes there's a gap.
These measurements are more easily calculated than directly measured.
In the front, you can measure from the outside of the seat tube or down tube to the chainring or gap, and add half the width of the tube.
In the rear you can measure the cogset centerpoint relative to the inner dropout face, and subtract that from half the OLN width, and arrive at the chainline number.

If the centerpoint of the new cassette's total width is in the same place relative to the centerline of the frame as the old cassette, your chainline will stay the same, and you do not need to change your BB spindle. If it has moved inboard or outboard more than 1mm or so, you might want to adjust your chainline for that. But it will probably be ok.

Does that make more sense?

Yes, thank you.