mazdaspeed

Long story short, I live somewhere that's almost entirely one hill after another, everywhere you go, and my bike's smallest chainring is 42t. The next one is 53t. Anyway, the 42t just does not cut it for extended periods of steep hill-age, so should I just buy a 30-32t and slap it on where the 42t was (will that work?) or should I buy a triple (which may require a new FD among other things, I'm not really sure). I'm worried about a smaller CR causing a dead spot but on the other hand a triple might be expensive to switch to. I'm running a 1986 suntour sprint (6 speed) group. I don't know about getting a compact vs. just switching one ring because I like having the headroom in the gearing for descents and hauling ass when it's flat.

Thoughts?

rcams

53/39 is a pretty common and standard crank combination. You can probably drop the 42 to a 39 easily enough. The next question is.....what sizes do you have on the freewheel?

mazdaspeed

I'm not positive but I think my largest gear is 23t in the back. Believe me when I say that I have to work HARD to climb steep hills.

Could I go smaller than 39t?

ProFail

I believe the greatest difference possible between chainrings is 14t. So, You could have a 53/39 but no lower. You could run a compact 50/36, a triple or get a new cassette. I personally run a 16-27 to stay in line with junior gearing restrictions. Quite the lamesauce gearing.

Wested

Gonna have to replace the rear derailleur as well, I think, if you want that triple.

merlinextraligh

If your current set up has a low of 42/23, you'll feel a big difference going to a 39/27. I would definitely put a 39 on the front and get a 12/27 cassette for the rear.

Odds are good that will meet your needs. If not, the next step is a compact crankset, or a triple.

And to go to a 39 inner chainring, and the 12/27, you'll need 1 new chainring, a new cassette, possibly a new chain, and a little adjusmtent; nothing more.

Easier and cheaper than going to a triple or changing cranksets to a compact.

nitropowered

the smallest ring you can put on your 130bcd cranks is a 38

BananaTugger

TA Specialties makes 38T rings for 130mm BCD cranks.

rcams

Going from a 42-23 to a 39-23 is a pretty substantial change. I would try moving to a 39 on the crank and see how it feels. You can spread as much as 16 on the front - I know because I have a 50/34 compact and with a compact Centaur FD the shifts are as smooth, if not smoother, than an older Veloce 53/39 setup.

mazdaspeed

Thanks for all of the advice so far. I think doing the triple would not be cost effective.

I think I have a 39t sitting around somewhere so I'll try that out and see what it's like since it will be easy. If that's not enough I'll do the cassette as well. I was thinking that 42 to 39 wouldn't be a very big difference but I'll take your guys' word. It has to be better than what I'm using now at least.

jrobe

"Downgrading to a triple"


Downgrading??? When you struggling up a steep and long climb with a triple crank, you will definitely look at it as an upgrade. There is no disgrace in bringing enough gears to the party if you ride regularly on hills.

It is expensive changing to a triple crank though. You can save money with a compact. Do a search here on triples vs compacts - endless posts.

Jasper Storm

You may be limited by the crank bolt pattern size. The vintage Campy cranks on my Davidson of roughly the same era as yours will only go down as low as a 41 tooth chainring. 52/42 or 53/42 were fairly standard for the NR era.

IRD currently manufactures a 13-15-18-21-24-28 freewheel that can be bought at Harris Cyclery. While the three tooth gaps aren't a big hit with the cadence crowd, the 28 tooth cog will make a difference in climbs. The ratio will still be nowhere near your compact riding friends, however.

EDIT: Forget this advice- I think the sprint RD has too small a capacity for the 28 tooth cog.

mazdaspeed

I consider it a downgrade because my pride far exceeds my strength and ability. I guess I would compare it to racing with ABS or traction control.

Your point is taken though.

Beaker

+1 - need to get past the macho BS here. A triple just means you can ride bigger hills, just check out the ride report on the Mount Washington climb.

I think that merlinextralight is on the money here though. It all depends how serious your hills are and how often you ride 'em.

mazdaspeed

Looks like the one I had sitting around is a 40t. Annoying.

How fast would you end up going on steep-ish hills with a compact double or a triple? Right now if I go less than 9mph in the lowest gear I fall out of the efficiency range and either have to stand and mash or just pedal harder to maintain 9mph.

dstrong 

I had a 53/39 on for the last two years but with such a small amount of riding (weekend warrior only), I switched back to my 52/42/34. I had forgotten how great that 42 chainring is. It reaches the entire range of the rear cluster and is perfect for my average speed these days. The little and big rings only see action when it gets a little steep going up or down. I run a 12/27 on the back. I found with my 53/39 that I was doing a lot of shifting on the front to avoid the cross-chain situation. It's a more involved change to go triple but I think it's the better bet given your situation.

Beaker

That's kind of a "how long is a piece of string?" type question. 8-9mph is a good comfort zone for moderate climbs for me in my 39, but your speed is down to the engine more than the gearing. Work on increasing your rpm and that should solve any concerns you have. A triple or compact just gives you more options, it doesn't make you "slower".

icyclist 

> I would definitely put a 39 on the front and get a 12/27 cassette for the rear. <

That's great advice if you're young and fit. If you're older and unfit, it's still great advice: you'll get into shape if you keep riding that combination. If you are surrounded by, and like to ride hills, and you want the low gears offered by either a compact or a triple, it'll cost you a chunk of change.

I'm old, I could stand to lose ten pounds, and I don't race, so I have a triple, with a 30t chainring. Insisting on a triple might have been a mistake, though, as I seem to be able to get up almost anything - e.g. 12-15% grades that run a half mile or so - with a 39t up front and a 27 on the rear.

That doesn't mean I don't drop down to the 30t once in a while; when I'm tired, I'll happily ride a gear that's about the equivalent of the lowest gear on a compact, a 30/24. I never have to go lower, no matter how steep the grade.

You won't be able to go that low just changing your chainring and cassette, but you could try looking for a cassette with a 28, and if possible, go with a 38t up front.

Or, something I don't think I saw anyone mention, you could both go for the smallest possible chain ring, and add a mt. bike rear deraillleur and stick on a 32 to 34 cassette. That would still be way less than switching to a compact or triple, and still give you a very low gear.

umd

I've found that with my gearing (39x26), 7mph is about as slow as I can go before I start to lose efficiency. That translates to a 10%-12% grade before I start to get bogged down and stand. Lower gearing lowers that speed (and therefore the power output required), so there is nothing wrong with that if you are having trouble with your climbs. As far as making you slower, you can always use a higher gear, so it doesn't make you slower, but it does allow you to be slower.

big john

It's not a cassette, it's a screw-on freewheel. Performance and Nashbar still have some of them. Some of them can be taken apart, and the cogs switched, like the early cassettes. I put a 28 on an early Shimano 600, even though people said the derailuer couldn't handle it. Just avoid cross-chaining.
Forget pride, if you're hanging with the climbers on your rides, it doesn't matter what gear it takes to do it. Some people spin higher than others, it doesn't make you less of a man.

umd

Although I have a "standard" crank I have a lower cog (26) than most of the people I ride with (25). I don't always use it but I find it useful so hey, what they heck. And I'm not going to have any pride issues switching to a 28 for Everest Challenge!

Phantoj

On an old bike, you could try sticking on a cheap old crank... the old RSX cranks (double and triple) were compacts (110 BCD), or stick a Sakae or Sugino triple on there - cheap...


https://cgi.ebay.com/Shimano-RSX-cran...QQcmdZViewItem

veloGeezer

technically it depends on your front deraillieur, but I have a 16 tooth gap (50/34) and I think that is actually pretty common as in no special front derailleur is needed.

What the limiting factor is going to be in this case is the span of the bolts on his crank arms.

Keeping in mind that the 130mm standard for full size cranks wasn't always the case for Suntour stuff out of the 80s, he might be able to get as small as a 36 to fit. I did that on a steel frame bike I restored out of the same era with suntour components a couple years ago. You will want to take your crankarm with you to go hunt for gears so you get the size of chainrings you need. It will be non-standard compared to today's bikes.

You can also change the 53 big ring to something else like a 52 or a 50 to get yourself a set of gears that fits the local roads. (like 52/38 or 50/36) When you do that, however, you may have to lower the front deraillieur on the seat tube, so if it is a braze on, you are stuck with it. If it has a clamp, you are in business. Just drop it down and readjust the cable.

Someone also mentioned looking at the rear cassette. You can find 5 speed freewheel/cassettes that go 14x27, but 14x25 is very common. Definitely do that if you are on a 23 in a hilly area.

so anyway, hope that all helps. I had the same thing with vintage steel frame bikes before, and I live in Pennsylvania, so I understand why a 42x23 for a low gear would be a drag.

good luck

rm -rf

From Mike Sherman's Gear Calculator. This calculator is great. You can plug in different chainring and cog combinations, and try any cadence with them.

MPH at 80 rpm.
You can see that a 39-27 will be a lot easier than a 42-23. The 42-23 is about the same as the 39-21, so you would have two more low gears.
Even just the 39 chainring will help, with one more low gear.

.......12...13...14...15...17...19...21...23...27
----------------------------------------------------------
53 | 27.7 25.6 23.8 22.2 19.6 17.5 15.8 14.5 12.3
42 | 22.0 20.3 18.8 17.6 15.5 13.9 12.6 11.5 09.8
39 | 20.4 18.8 17.5 16.3 14.4 12.9 11.7 10.6 09.1

ElJamoquio

I've done 17 tooth difference in front, no problem. The 50/33 and 11-28 (or 12-27) combo is a pretty potent one for mountains.