LarrySellerz

Hey guys, I joined a group with a 42x18 ss and had trouble keeping up on flats and long straight descents, but it was a pretty savage ratio on the hills (Huddart park for Bay Area folks.) Have you played around with ratios to try and keep up with road bikes? It’s hard to imagine getting up some of the steeper hills with a heavier ratio than what I’ve got

veganbikes

Find a gear that works for you! For me that was generally 42x16 back in the day and now 46x17 but that is me. You probably want to ride a road bike with other road bikers if you are having trouble or just don't bother keeping up with them and go on your own ride, they might appreciate it more. On descents on a fixed gear unless running a ridiculous gear you couldn't run elsewhere except downhill there is no gear you won't likely spin out on it is downhill.

Ymerej

That’s a very personal question every body has different fitness levels. No matter what you are always in the wrong gear when riding fixed gear on the road. Best thing to do is find what gear works for you and do your thing, if you can keep up Roadies that’s great and if you can’t that’s fine to. Fwiw I run 51x17 and at times it’s a SOB but constantly striving to get stronger and faster
just try to find a everything gear that does it all.

acoustophile

As already stated, this is a personal thing an depends on your strengths. Assuming that you want to ride on the slower side average of 20-25km/h (12.4-15.5 mph), running a 42x18 (assuming 23c tires), you'd need to average around 70rpm just to hold the low end speed of that range. Increasing the cadence to 85 RPM would get you into the upper echelon around 16mph but that would be hard to hold down for long periods of time. Competitive cyclists pedal at an average cadence of 80 to 105 RPM. None of this even takes into account watts.

I would measure the average cadence that you can sustain for long periods of time and your desired speed on flat ground and play with gearing from there.
https://www.bikecalc.com/speed_at_cadence

JohnDThompson 

Riding fixed with a road group on mixed terrain pretty much guarantees that you will be dropped on the hills. Too low a gear, and you'll be dropped on the downhill; too high a gear, and you'll be dropped on the uphill. Personal choice will dictate which gear/group/routes work for you.

Rolla

IMO, "keeping up with road bikes" while "getting up steeper hills" calls for a different tool than SS. Personally, I gear for the hills (approx. 63 gear inches on most of my SS bikes), and let the roadies wait for me on the fast flats.

mrmb

You are basically trying to defy the laws of physics.

Anything that helps you going uphill, hurts you going downhill and visa versa. The ideal gearing for the flats, will hurt you on hills.

There is no free lunch. Sorry.

Find a combo that works most of the time and deal it when it doesn’t work so well.

wolfchild

63 gear inches fixed or singlespeed is one of my favorite gear ratios for all around riding which includes pavement, gravel , some hills and some mild singletrack...but there is no way that I can keep up with roadies and their geared bikes on the flats. I get passed left and right when on the flats. If your goal is to keep up with the group then you need to get a geared bike.

LarrySellerz

My ratio is 61.3 gear inches, and the ride in question attempts to stay together for the flats and goes all out on hills. I could kind of keep up on the flats but I have to be careful not to eat wind because I’m wasting a lot of energy pedaling at a high cadence. My legs were fresh for climbing though, it was an interesting workout.

wolfchild

I am using 42 x 18 with 700 x 45mm gravel tires and it works out to be 65 GI... one of my other bikes also has 42 x 18 drivetrain but with 32 mm tires and that works out to 62.9 GI.

LarrySellerz

I just plugged in into an online calculator, weird how we are getting different numbers. The wheel diameter shouldn’t be effected by tire size

wolfchild

Wheel / tire size definitely has an effect on gear ratio. It's small but the difference is noticeable when riding

SnailMaster

To restate what’s been said, it’s a personal thing based on so many factors. I spend a lot of time on my bike, lots of hill-climbing (12-15% grade max on most rides), descending, skidding, etc. I am 40, and in pretty good shape. I ride about 30+ miles a day and I swear by 42-20, but then I can rarely go above 25 mph. That being said I usually pass the road bikers about half way up the hill. And I corner pretty fast and spend a lot of time on steep narrow and twisting roads, so my skidding and cornering also provides some advantage there.

Rolla

Tires are usually about as tall as they are wide, so tire size absolutely affects overall wheel diameter and thus gear inches. Bigger tire = bigger wheel = bigger gear.

bensanford

I find that fixed is vastly different from single-speed and prefer fixed. It is easier to climb in a higher gear on fixed-gear than on a freewheel bike. Since the pedals move forward when the bike is moving, it helps the pedals push through the dead spots at the top and bottom of the pedal stroke, so I can climb slopes on fixed at 69-gear inches, where I would probably shift down to something like 42-24 or 42-26 if climbing the same slope on a regular road bike. I generally use about 69 gear-inches on the road when on fixed-gear - so I have 42-16 on one bike, and 44-17 on another. I shifted to a higher gear (44-18) on a long relatively flat ride to better keep up with other road bikes.

If using a freewheel on a single-speed you are somewhat forced to ride a lower gear to climb, and that makes it even more difficult to keep up on the flats.

Regardless, keeping up with the road bikes will also depend a lot on the terrain. Rolling hills (even short and steep) are much better that longer slopes. Keep the horizontal wavelength short . Mile long climbs or Decents would be a problem keeping up on the downhills. Tailwinds would also pose a problem.

Riding fixed generally forces you to attack the hills - keeping your momentum up from the downhills to get up the next slope, and that means being able to spin at high cadences. In excess of 150 RPM is possible for short periods...

rustystrings61 

The older British cycling manuals used to suggest a 65-in gear for freewheeling bikes; the medium gear ratio time trial folks used to set an upper limit of 72 fixed gear inches. I've been running right around 70 fixed inches for 24 years over the rolling terrain of what the realtors have taken to calling South Carolina's Lakelands with a fair bit of success, including club rides with roadies - but NOT hammerfest rides. As mentioned earlier, one attacks on the climbs, learns to love to dance on the pedals as the momentum slows, and to perfect spinning as smoothly as possible on descents. It helps if you ride with people who are familiar with fixed gears and understand they will need to pass you on descents.

I am in bensanford's camp - I vastly prefer fixed to single speed for climbing, for the same reasons he outlines.

Not mentioned so far, but be sure the frame geometry works for you on the bike to get the fullest use of all of your muscle groups. I like dropped bars because they provide different positions that help with getting into a spinning position, sitting way back on the saddle whilst gripping the bars near the stem and "turning 'em 'round" a la 1950s British club cycling doctrine, grabbing the brake lever hoods to stand and honk up the steep bits, and going down to the drops to muscle up short sharp uphill moments. I run 42x16 and 45x17 on the two bikess with 28 mm tires and 44x17 on the bike with 35 mm rubber.

stevel610 

Truth. You can "keep up with the road bikes" or "get up steeper hills". Choose one.😉

IAmSam

Back in younger days I spent many weekend mornings bird-dogging roadie groups on my sw8 phiksie...even caught-up with some occasionally.
In fact it was kind of built as a roadie chaser

I never met a serious group that could not drop me at will...

veganbikes

Yo you gotta post pictures of your Eisentraut here! Get those 10 posts and get those pictures loaded.

Carbonfiberboy 

Back in my early 60s, I led a group ride series of mixed fixed, SS, and geared bikes. I used 42 X 17 SS with 23mm tires. The climbs were tough - up to 10%, but i could coast on the descents and keep up on the flat with the geared bikes as long as I was sitting in. I remember long stretches of 135 cadence in the paceline, so at least 25 mph, maybe more, I don't remember. I couldn't hold over 20 mph pulling. I was one of the weaker riders. I'm a good descender though, so what I lost on the climbs I could make up on the descents and get back on. With a SS it worked out well, really improved my spin. I used my ordinary road bike and just didn't shift. The series didn't make me any faster on rides when I could shift though. I was surprised at that. I think that's called the rule of specificity.

ThermionicScott 

I think I first read about "medium gear" on Steve Morris's site, and promptly fell in love with the idea for all-around riding. My spring/summer/fall gear has been roughly 71" ever since.

beng1

Easy way to keep up with multi-speed bikes on a single-speed is to make sure those you ride with are decades older than you, solved.
I always wonder why people have a hard time figuring out what ratio they need for a single-speed bike, don't they know what ratios they used to ride in when on their multi-speed road-bike ??? The gear ratio I used for almost all of my riding on my ten-speed Huffy road bike was a 52/19, so when I built up my "LeToaster" single-speed coaster-braked bike, I put a 52/20 on it and it is absolutely perfect, I nailed it first time. It is of course a bit slower on level road, but I was always able to go a bit faster than most I rode with so that is no problem, and the extra tooth on the back works fine for grades up to around 5%, if they get steeper than that I just get off and have a nice walk. I would never expect that there was some magic ratio that would let a single speed keep up with a multi-speed bike, nobody with any education would.

Trakhak

Yep. I've been riding approx. 71" fixed gear since 1964. Starting to feel it in my knees, though. Probably time to give up on fixed for me.

1989Pre

When my derailleur went bust at one time, I rode 46T-14T, and that was fine for flat (tiny hills), so now, as I am building my first fixed-gear, it'll be 50T-16T, which is about the same. I have no illusions of getting up big hills, though, so unless it is a slow group (I ride with some), I'll do it alone. I'd rather walk it up the big hills than to constantly spin out on flats.
Yoga and Kung-Fu stance work are key for the up-hills.

Dylansbob 

My old commute across the Narrows was probably similar terrain. Before my hip failed, I would keep up with coworkers on the commute on a 39/18. That would require a few seconds spun up to ~200rpm on some of the descents, but it was low enough I could keep touch on the way back up.