Toying with a fixed

[WombleStu]

Life long cyclist - Audax and club rider : tours to France and a gravel adventurer..
But never a fixed …
Can someone tell me if a 46 front tooth and a 17 or 18 tooth rear is easy for flats (spinning) or a good point to start on ?!?
I am looking at the Dolan FXE with a flip flop single speed same 17 or 18 on rear
Thanks

 

[Sharky]

46x18, should be ok. About a 68" gear.

Fixed sprockets are very cheap, so easy to replace with a 19t or 20t.

Assuming you have a chain whip.

 

[fossyant]

I would advise using an odds (17T) sprocket as even's sprockets do wear to the chain links, so if you haven't removed the wheel for quite a few miles, and refit, it may sound like a tractor. This doesn't happen with odds. I ran 72-74" for a 10 mile commute with some lumpy bits.

 

[colly]

I use 48 x 18 . Its ok for most hills but not for steep stuff.
Im noticing that hills are becoming more difficult.

Getting old.

 

[Sharky]

Ascents are hard on fixed, but it's the descents that are really scary. I switched from fixed to single freewheel to make the descents easier and faster.

I still ride fixed for TT 's, but with a much higher gear and can still be scary on a fast descent.

 

[rogerzilla]

47 x 18 is optimal for sprocket wear, but 46 x 18 is still very good. 45 x 18 is terrible.

 

[Sharky]

I use 48 x 18 . Its ok for most hills but not for steep stuff.
Im noticing that hills are becoming more difficult.

Getting old.

Something to aim for......
48x18, equates to a 72" gear, which was known as a "medium gear' for early season 25 mile time trials.

The record is held by the late Zak Carr, who did the 25 miles in just over 53 minutes.

 

[ivegotabike]

Something to aim for......
48x18, equates to a 72" gear, which was known as a "medium gear' for early season 25 mile time trials.

The record is held by the late Zak Carr, who did the 25 miles in just over 53 minutes.

Legs going like a bee's wings!

 

[Fastpedaller]

I used fixed for a lot of my club riding and time trials up to 12 hrs many years ago and had stronglite cranks and a TA ring which gave (as near as possible) a perfectly concentric chainring. I've since considered going with fixed again for Winter riding, but the modern cranksets just don't have such good tolerances........ It's very easy to get an alternating tight and loose chain, but extremely difficult to get to a uniform tension for a complete revolution of the cranks. I'm using a single freewheel on my Winter bike and can get the chainring suitably central for that application, but wouldn't feel safe on fixed unless I could get it better. I add I'm a retired engineer, and although I'm fussy about such tolerances, I'm also pragmatic enough to accept limitations if they are safe.

 

[colly]

I used fixed for a lot of my club riding and time trials up to 12 hrs many years ago and had stronglite cranks and a TA ring which gave (as near as possible) a perfectly concentric chainring. I've since considered going with fixed again for Winter riding, but the modern cranksets just don't have such good tolerances........ It's very easy to get an alternating tight and loose chain, but extremely difficult to get to a uniform tension for a complete revolution of the cranks. I'm using a single freewheel on my Winter bike and can get the chainring suitably central for that application, but wouldn't feel safe on fixed unless I could get it better. I add I'm a retired engineer, and although I'm fussy about such tolerances, I'm also pragmatic enough to accept limitations if they are safe.

I can't say I have ever noticed the full revolution being tighter then looser except when the chain is tight. Well too tight, certainly for me at any rate.
I read somewhere ages ago the midway point between sprocket and chain ring should move up and down by about a quarter inch. I found that tight. So I keep mine at around a half inch. I believe that's considered too loose but it suits me. Its not so loose the chain can jump off the teeth but neither does it bind.

 

[Cycling Badger]

TLDR;
- Your suggested 46/18 gives ratio that I find a good for commute / short cafe-ride where gradients are moderate
- However, what's good for one-man may not be great for another; you'll need to play around with ratios to find out what works for you.
- Fortunately changing the rear sprocket isn't difficult nor expensive.

----

I have a couple of single speeds for basic commuting and running earns.
One is 44/18 - This is literally for nipping to shops and going for coffee.
The other is 39/15 - This was my commute bike; about 30km each way with a few short and sharp hills.
I find these ratios pretty utilitarian and find I can tolerate short climbs below 10%
I also have a fixed wheel for the second bike which I tend to fit in the summer and when I want to give my legs a good workout.
It's also a 15t sprocket - great for gentle cruising on the flat but can still push into a headwind.
However, going downhill is challenging and I do tend to rely on my brakes to moderate speed on anything but a gentle down hill.

For reference :

from Bicycle Gear Ratio .com