mtb_addict

i got 36x16 SS aetup i been riding for over a year. perfect for my slow riding, stop-n-go style here.

just ordered a new fixie hub with 16teeth. going fixed gear only.

i dont plan to ride any big hills, but there is alot of overpasses and underpasses here. i ride in urban setting.

can i hold off on getting a bigger chain ring?

going downhill with only a front brake. is that going to be problem? i dont have rear brake on my bike, and there is no rear brake bridge to allow install.

stevel610 

What size tires does the bike have?

For road riding 60" tends to be low, but it's your bike and your riding. If that setup works for you its good.

For most people front brake only works fine for fixed riding.

mtb_addict

3835mm wide tire. it is a townie bike. i ride MUP alot. i am only worry about going downhill being forced to pedal super fast.

stevel610 

Wheel diameter too. 26" 27.5" 700c/29".

mtb_addict

26x 1-3/8. ...iso 590.

equivlanet to 35mm wide.

Rolla

That's lower than the singlespeed gearing I have on my 26" BMX cruiser. It'll be hard to find a middle ground between descending too fast for your legs and riding the brake too much, spoiling the fun. Try it and find out, but I'll wager you'll be getting that chainring sooner than later. You don't have to go to 70 gear inches, btw -- I think 65 is a lot of fun if you don't have extended or steep descents.

Mikefule

Somewhere in the 60 to 70 inch range is good for many people riding on the road.

I recently lowered my gearing a tad from 66 inches to 63 inches and my average and top speeds are virtually identical, but it feels easier.

I can max out for very short distances down hill at a peak speed (recorded on GPS averaged over 1/10 mile) of 28 mph (say 45 kph) but it's not comfortable for more than a few seconds much over 20 mph (32 KPH). Average ride speeds on mixed terrain on and off road tend to be 10 to 15 mph.

60 is a bit lower than I'd go, but if you don't mind feathering the brakes on some of the downhills you'll be fine.

Each to his own. There are no rules other than enjoy it.

GMull

Are you clipped in, either toeclips or cleats? Without any attachment to the pedals it can be quite painful if your feet slip off whilst going downhill.

rustystrings61 

I have been running a 60-in fixed-gear for gravel and dirt roads and it's just about ideal in that application. I still prefer around a 70-in gear for pavement, though. And I run brakes fore and aft, either way.

TejanoTrackie 

That's actually the same as 650A. You said the tire is 35mm, which is not fractional, so I'm not sure what you've got here. What is the ETRTO number on your tire ? Is it actually 35-590 ?

stevel610 

Here's a chart from BikeCalc based on a 584 erto tire. 584x35c-close enough. Gives you rpm's with a given gear. I put in 36 / 40 / 44 chainrings and 16-23t cogs. It shows cadence at a given speed. Therefore, you'll be spinning 70-90 rpm to hit 15 mph if you decide to change the chainring. Good luck!

stevel610 

And the gear inches for the same ratios.

mtb_addict

"35mm" came from my own hand calculation.

my tires size (26x1-3/8) is like the pic below. i am in East Asia. This tire size is popular on cheap bikes.

79pmooney

Regarding gear choices for fix gear - Ride your best guess. Go up or down as needed. Any gear is a trade-off between high RPMs downhill and the impact on your butt and ease of climbing. And where you want to be gear-wise when the road is flat. This is so up to you, your body and your riding preferences that others on a forum cannot possibly guess what you should ride. Until you actually ride something, you will not either.

Related to the gear choices are: clipped in or toeclips or are you riding platforms? Are you skid-stopping? Positive foot retention allows both higher RPM downhill and more torque uphill, allowing a higher gear but a higher gear can be harder on your knees skid-stopping.

Experience on fix gears also plays in. Lots and you can comfortably ride lower gears downhill. Now, you can always bleed speed with your brake to stay within comfortable RPM limits. (A rear brake helps a lot here. It doesn't need to be much of a brake. I know you said you didn't have anything there to put it on. Maybe post a photo and see if anyone knows of a good fix.)

In general I am a fan of paying real bucks for high quality fix gear cogs, but this is where I'd make an exception. It may take you several tooth choices to dial this in. If money is tight, going cheap and being able to buy 2, 3, or 4 to get the right gear could be a very smart move.

TejanoTrackie 

OK. 37 is the tire width in millimeters and 590 is the bead seat diameter (tire inner diameter) in millimeters. 1-3/8 is the approximate tire width in inches, which computes to 34.9 mm, but the exact width per the ETRTO standard is 37mm, so this number should be used when computing gear inches, since the tire width is also assumed to be the tire height. The 26 number is quite useless in determining wheel size and gearing, since the BSD can vary from 559mm on tires with decimal widths such as 26 X 2.125 all the way up to 597mm on tires with fractional widths such as 26 x 1-1/4 EA1 used on rims common to old American Schwinn bicycles. Anyway, in your case using 37-590 and 36 x 16 gearing, I calculate your gear to be 58.9 gear inches. This is not much lower than one of my town bikes that I ride on some dirt and unimproved paths with 61.4 gear inches. Given that your bike is probably heavier and the wider tires have more rolling resistance, if it were me I would not bother to increase your gearing. As to using the front brake to control your speed on downhills, I do this all the time on my fixed gear bikes with no rear brake, and it is never a problem unless I'm riding on a very slippery surface in which case I rely on my legs back pedaling against the rear wheel. Just remember to continue pedaling while going downhill, and let the front brake control your speed.

mtb_addict

very hot humid here. in suummer, i always wear my Tevas sandals. But sandalls probably wont work with pedal straps. so i plan to not use retention.

and i figure it wiill be easier to take my foot off the pedal if the cadence become too high.

Rolla

Other than maybe swim fins, I can't think of a worse footwear choice for high-rpm fixed-gear descending.

TejanoTrackie 

The last thing you want to do is take your feet off the pedals while riding a fixed gear bike.

Swampthing 

sorry to hijack the thread, but I want to build up a BMX fixed gear.
what kind of hub did you use? Rims? did you build the wheel or buy one?
I am an old guy, but sometimes I still just want to thrash a little and ride up and down the levee banks and do stupid stuff that would not be fun on my road bike.

Rolla

My BMX cruisers are singlespeeds, not fixed gear. My 26" has 32-hole Surly Ultra New hubs and Sun Rhyno Lite rims that I built; my 27.5" has the stock WTP 36-hole disc hubs and rims that came on the bike.

Broctoon

60 gear inches too low for fixed gear riding?

If you're going up lots of hills, definitely not.

If you're descending a lot (especially anything steep), yes.

In mixed riding, it's a bit on the low side, but not extremely. You say you ride mostly MUPs. The paths in my area tend to be quite flat--if it's the same for you, then 60 inches is reasonable. You won't be able to cruise very fast, but starting and stopping will be easy.

Broctoon

To answer MTBaddict 's other question, going down hills with only a front brake (on fixed gear) is not a problem.

I use my legs to slow down a little or manage speed on shallow slopes. On moderate slopes, I start using the front brake and might supplement it with my legs. For steep hills or when I need to come to a full stop, I'm definitely relying on the brake. But I've never seen the need for a rear brake on any of my FG bikes.

If you're mostly going up and down overpass ramps, with 36x16 gears you might find you seldom need the front brake. It's still *strongly* recommended to have one. Rear brake, phooey! It's like your appendix--no need for it at all.

xroadcharlie

I'd probably like about 65 - 66 gear inches if I where riding with some hills and against a sometimes moderate wind. This translates to 15 kph @49 rpm and 25 kph @81 rpm.

My bike has a 62 and 70 gear inch cogs among it's 21 speeds. 62 is frustratingly low when I tried keeping in there on mostly flat land. 70 is a pretty good balance most of the time, But against a moderate wind is a little high for comfortable riding. On most rides I might use my 50 - 78 gear inch cogs. With a light tailwind, Or descending a low grade 78 gear inches is very useful, While peddling against a moderate wind(20 - 30 kph) I found 55 gear inches to be good.

I think the front brake combined with using your legs to slow the back wheel (engine braking) will be fine as long as you don't let it get out of control, Like descending steep hills at 35 kph. Definitely give yourself some time to get used to the bike and it's braking.

takenreasy

To each their own. I ride 72 GI and wear Xero Colorado sandals. They are perfect because they keep my feet cool and I don't adhere to cycling dogma plus I'm getting old and don't care what others think. Whew, and I can also do run-on sentences.

Rolla

It has nothing to do with dogma or individuality. The OP is a first-time fixie rider on a 26" wheel and a 60-inch gear with no foot retention. You might recommend sandals, but I sure don't.