Should I change my gearing?
 

I picked up a vintage Specialized Epic road bike a couple of months ago and have been enjoying riding the bike. I'm concerned about not having any low climbing gears. The front rings are 52 and 42. The 8 speed rear cassette is a 11 to 25. I have avoided any serious climbing with the bike so far and have found I have been able to handle minor climbs fine. I'm concerned that if I took this bike where any serious climbing was involved, I might go anaerobic before hitting the crest.

I was considering putting a 11 to 28 cassette on the bike and changing the 42 tooth front sprocket to a 39. The rear derailleur is a short change Shimano 600. The front derailleur is Shimano 600 also.

I'm not sure the derailleur would handle the gear inches and if the changes would be worth the cost. It shifts flawlessly right now. I'd hate to mess up a good thing.

What do you guys think?

I think the changes you're contemplating will give you about a 20% advantage at the low end over what you have now, and IIRC the 600 rder will handle a 28.

But will that get you up Mt. Hood without going anaerobic? I doubt it. Why not a bigger rear cog and a der with a long cage?

20% is nothing to sneeze at, but why not try the hills that you fear now? That might giveyou an idea if 20% is enough.

Buying a new crankset with a 110 bolt circle lets you drop the chain ring size to 34t
50 - 34 combinations get put on the bikes at a factory level lowering costs .. by having big sales numbers..

What are your fitness plans? It's early spring. That gearing could work if you're planning to put in a lot of time climbing hills and getting stronger.

Otherwise, I'm with @fietsbob. A compact crank would lower your overall gearing a bunch without needing to swap derailleurs or cassette. :thumb:

IRD has a 13-15-17-21-25-28-34-40t elite cassette. and a 12/13/15/18/21/24/28/34 cassette.

50-34 would be good to try if feasible

Shimano maintains a library of technical documents for download. If you know the exact model of the FD you can go to the site, look up the document and see what the maximum difference can be. https://si.shimano.com/#/en/search/C...leur&type=ROAD
If you look at this example https://si.shimano.com/pdfs/si/SI-U-109-000-00-ENG.pdf under the heading Specifications you will see this particular FD has a maximum difference of 15 teeth.

Your vintage crank probably does not accept a 39 tooth chainring. You could probably find a cheap replacement crankset, new or used, that would work with your current bottom bracket.

A bicycle is a simple machine but the devil is in the details.

Everything on a bicycle works together so you can almost never change just one part without having to change something else to make it work. "Vintage Specialized" tells me that you don't want to spend a ton of money on your proposed changes. New chainrings may require a different crankset. Different crankset may require a different bottom bracket. Bigger cassette cogs may require a different rear derailleur. A different derailleur might not work with your shifters.

Thanks guys! I went out on a nice 50 mile ride with the bike today. There were some reasonable climbs with nothing too extreme. There were a couple of 2 mile climbs that were around a 4% average grade and I had no issues with those climbs. I also ran into some short steep pitches that required me to stand up to get past them.

I am not sure how much money I'd want to spend on changing things. Changing to a compact drivetrain is a cool idea. I'm not sure I want to spend that much. I really like the way the bike feels. I may need to just be cautious on which routes I take when using it. If I'm on a ride with serious climbing, I'll have to use my other bike.

Still, I may eventually change the drivetrain on this bike...

Cheap option
Put an old mtn bike RD and cassette on it. Even if you buy brand new they cost $20-30 each since 8-9 speed stuff is worthless. You can go all the way up to 11-42 even with 8 speed though I imagine the gaps on a road bike would be horrifying.