Chesterton

My road bike is a 1990 Schwinn World Sport. Like a lot of the bikes of that era, the front gearing is 52/42. The rear is a Shimano 7 speed 12-28 cassette. I use the bike for light touring/randonneuring: 50 to 100 miles at an average moving speed of 14 mph or so (speed on a flat open road 16-20 mph). What I am finding is that the lowest gear 42-28 is simply not low enough for the hilly countryside that I want to ride in. When I get into any significant or sustained climbs, I run out of gears fast and I end up mashing the 42-28, which is probably not good for my knees. And once the grade gets above 10% or so, I have to just get off and walk the bike, which can be quite time-consuming.

So, my idea was to change the front chainrings, as the least expensive way of getting lower gears. It is a 110mm BCD spider, and I have ordered a 34t Sugino ring (the smallest possible for 110 BCD). My thought was to remove the 52t outer ring, move the 42t inner ring to the outer position, and put the new 34t in as the inner ring.

I understand the front derailleur will need to be moved down the seat tube to fit the new smaller outer ring. I'm putting a new chain on as well, which I understand will be shorter than the old chain. Is there anything else I should be aware of before I start this project? Does the size/shape of the derailleur cage present any issues?

The other possibility I considered is just swapping the 42 for the 34, but would 52/34 be too big a jump for the derailleur to handle smoothly? I'm considering that because I'm wondering if 42 is too small for the big ring. I certainly do use the 52t ring when I'm on an uninterrupted flat road, or when pedaling downhill, but I looked at a gear calculator and it looks like 42t still provides a top speed of 25 mph at 90 rpm, which is way faster than I ever go on the flats anyway. So maybe 42/34 would be just fine for my needs?

Regarding other suggestions like getting a triple crankset, etc., please understand I'm looking for the most affordable way to improve this bike for my purposes. If I was looking to sink a significant amount of money into this, I would most likely be buying a new randonneuring-specific bicycle, or at least I would be modifying a higher-end vintage frame that was designed as a light touring bike from the start.

Thanks!

fietsbob

If you perform the Up Shift from the 34 to the 52 only when at the crest of the hill , so,

You take all tension off the chain and then you should be able to shift up to that big ring
with (a friction shift lever with) out resistance.. long cage MTB type takes up extra chain slack..

50-34 combinations are very common now ..





./.

Retro Grouch 

You know, you can get a hill climb gear almost as low by replacing your freewheel with a Shimano mega range freewheel with a 34 tooth biggest gear. You'll also need to install a new longer chain.

Chesterton

It's a freehub cassette, not a freewheel. I have that megarange freewheel on my cargo bike, though - it is nice.

Chesterton

Having read about this a little bit more, maybe the existing front derailleur would be able to handle 52/34 better than 42/34? 52/34 is close to a standard modern compact double. But is that too big a jump? Or am I likely to need a new front derailleur in order to handle the 34t inner ring, regardless of what size the outer is?

andr0id

I think your first plan is better. Even modern compact cranks only support 16 tooth difference of 34/50. I doubt you will get any joy trying to get a 1990 FD to make that shift.

Also, the new big/outer rings have a lot of metal bits and grooves to help the chain up. Your current 52 is smooth on the inside.

You could *try* a new 48 or 50 outer ring, but big rings are more expensive, so it depends how much $$$ you want to throw at it.

ThermionicScott 

13-34 cassettes are available, too.