So a couple of months ago I bought a 1990 Steel Specialized Hardrock Sport. The frame is in really good condition. I ditched the rims and got some used ones. I have decided to make it a single speed set up for mountain biking. I live in ky so there is some pretty steep stuff around here. I am just talking trail riding though...nothing crazy. I was wondering what size cog to use in the rear....the chain ring is 28, 38, 48. I was probably going to use the 38...but wouldn't be agains using either of the others.

Also I am stripping all the paint off and have acquired some decals for it. I am going to make it a raw steel finish and put a buttload of clear coats on it. I'll post some pics when I get a chance.

Lastly is single speed mountain biking a good idea or popular?

I would go with the 28. If it's really steep where you live, maybe a 17t cog in the rear. I'd ask over on the mountain biking forums about the gear ratio; they'd probably be able to give you better advice. Yes, it's extremely popular right now (although usually on 29ers). Yes, it's a good idea and will make you a stronger rider.

Singlespeed MTBing works best on tightly winding trails. You'll need a gear ratio that is much lower than you would use on the road. Winding trails are best because endlessly spinning a tiny gear through long straight flat sections of trail is just no fun.

If you ride several trails, you'll probably need several cogs or freewheels. With a 34 tooth chainring and 26" wheel, I use a 15, 16, 17, 18, and 20 tooth freewheels depending on the trail. I'd start with something close to a 2/1 ratio and adjust as needed.

Prepare to spend a lot of time out of the saddle mashing up hills! This is a good thing...I find myself blowing past geared riders on climbs. As a rule of thumb, I generally use the highest gear that I can successfully clear the steepest hill..that way I can go fast on the flats but still not have to walk up the hills. If its a really tight, winding trail, where high speeds are not possible I will gear down even more.

as suggested by the site https://63xc.com/ a lot of single speed mountain bikers go with 63 gear inches or so... pretty low, but then again you're either riding up a mountain or you're coasting down

it is definitely growing in popularity. i use a 2:1 ratio. i think i run 32x16? it works well for tight XC stuff, i don't have the legs to get up things that are really steep though (unless i am transitioning from a downhill to build up speed)

Depending on where you're riding I would either run the 28 with a 16, or the 38 with about a 22. S-Tree is real close to you and a blast, but somewhat of a challenge to gear for. If you do plan on riding there I would still stick with a moderately easy gear and accept that you will be coasting most of the way.
Where all are you planning on riding?

Well I ride at S-Tree and Turkeyfoot(I think that is what it is called), also I ride the local trail here in Berea, nothing difficult there I just like the ride. And occasionally there is a singletrack trail in London that I go to, my fav by far, but really long drive to get there though.

I was thinking of running the 38 with a 17 or 18, but I know that would be rough on S-Tree for sure.

dude run 32x16 or 17, 18 that combo is winning races in new england. of course, it depends on the course. run an 18 makes hills easy and if you haz high cadence it ain't no thang on the flats

i find 2:1 way too steep for most of the crap i ride.

i rode 34x20 on a 26er and now run a 34x21 on my 29er.

the 38 with a 21 or 22 in the back is what i'd recommend unless your real strong or your trails are pretty flat.

just like fixed; you don't need to push a monster gear if you can spin well.

Just for clarity, it should be noted that 2/1 on a 29er is not the same as 2/1 on a 26er. On a 29er the same gear ratio results in a higher effective gear due to the larger wheel. The standard 2/1 ratio commonly recommended for SSMTBing is for 26ers. The equivalent ratio on a 29er is less than 2/1.

Correct.

If you want to figure out equivilent gear ratios between 26" and 29" wheels, google "gear inches", or look it up on Sheldon. ...or just add two teeth to a 'niner.

Singlespeed mountain biking is a blast! The same type connection you get riding fixed on pavement, but off road. You find yourself immersed in the trail and anticipating. You learn to be a much better climber, improve your cadence and endurance, and, if riding rigid, greatly improve your line choice. It also helps you to be a much stronger rider, allowing you to push higher gears on your geared bike, and rocking your quads, calves, biceps, and lats from standing and climbing all the time. It will help you to become a better overall rider.

As for gears, I start at 38/19 or 38/20 and go from there. The 2:1 on a 26 advice is a pretty good starting place, but adjust it as you need. As you get stronger and learn to conserve your momentum you will probably go to a smaller freewheel.

Above all, have fun.

-Rob.

dude go for fixed mountain biking for the ultimate experience.
-durty

i run 32:18 on my 29er (rigid)... sooo much fun, only had to walk one hill.


i find i only spin out on long down hills, or on the road.

I will agree with that but it really depends on the nature of the trail. I don't really care for riding fixed on highly technical trails, trails with long downhills, or trails with tons of rocks, log piles, and other things to clear. Its not that I lack the skills, because I can manage trails like that fixed, but frankly its just too tedious, which disrupts the flow and slows you down.