What do you think of this gearing?
 

is 42:17 singlespeed too much for my 5'1", 100lb girlfriend? I can easily spin up at that ratio but I'm 6'1" and 180lbs. I'm afriad the bike I built for her will be too hard for her to get going. Any thoughts?

It depends on how much she rides. My girlfriend rides a 42x16 for a fixed gear that should be ok for her if she is any sort of a rider.

Hehehehe ok...my g/f is no sort of rider...how about that?

42/17 may be a little steep to start, but if you've already got it built, let her tell you that. You could go to 42/18 or scrounge up a 39 or 40 chainring... Those are both not-uncommon sizes.

Try a 42x20 to start off. She can always go smaller on the freewheel and take links out of the chain. There are 20-tooth freewheels on eBay for cheap.

if she doesn't ride very often then you should start her off with something a little less strenous, keep it fun for her. i'm 5'-1.5" & 98 lbs and i run a 46x18 on my converted ss road bike. it might be a little too easy for me, but it's nice to be able to cruise. let her feel relaxed on the bike, she'll be able to enjoy it more. gosh, you're like a whole foot taller than her...

hahah yeah and almost twice her weight. I have the other cogs from the cassette I can use. I'm sure there's one closer to 20 in there. 2 to 1 ration just sounds nicer too. Thanks for your help.

46x18 is actually a bit shorter gear than 42x17 (65 v. 67 gear inches with a 700x23 wheel and 165 cranks). 42x17 should be pretty doable for her if there are no hills. If she _really_ doesn't ride much go umpadumpy's route.

i'm thinking it will be fine. aren't most people used to riding at lower cadences anyway?

Yeah. Initially pushing (read: lower cadences) seems easier than spinning because you don't take endurance into consideration.

This is why novice cyclists become dependant on freewheels; they get used to pedaling like crazy on harder gears and just coasting as soon as they get tired.

Another thing to consider is the ease of learning to skid/skip/trackstand with a low gear. I'm currently setting up my girl's ride with 38 x 15. which is 67 gear inches. a great starting point for fixed gear. i've ridden that gear for a while for work and it's a blast. your gearing of 42x 17 gives 65. which is perfect.
also remember how slow you rode iin general when you firts started riding fixed and brakeless. so a low gear is fine.

I dont understand all the conjecture.

put her on the bike. If she says its too hard, change gearing.

Well, she's no where near that level of trying to do track stands or skids. It's a singlespeed, effectively a BIG BMX :-) I think I may go with 42:21....to keep the initial confidence high. Just alittle background on my gf she'd rather ridein a BMW than on a bicycle and she thinks campin in an RV at a KOA is "camping".

What style is the bike? I think her ride position will make a big difference. The more upright, the easier gear she'll need. Way up, heavy frame ... 38-19. Down toward a drop position a much harder gear is easy to push.

I'm just starting out and have bad knees so I'm going 44-20 (flatland here). I ride quite a bit and do like to spin. I still have the freewheel & cog and 44-22 is sweet, but I think I want just a bit more for moving along.

Good Luck and just make it clear to her that it is something you can change.

Yeah, start out low. 42x17 might be a little high if she's not a rider, really, but I can't imagine it being too out of hand. She can always adjust to suit.

42x17 oughta be ok, if she isn't riding much now then there's no reason that she should even need to be able to spin it at a high cadence right away anyway. She can tool around very comfortably at that ratio with a slow peaceful cadence while she gets the feel of it. My lady is riding 44x16 on her commuting fixed gear, doesn't go too fast and as a retired messer she doesn't care too either, peaceful cruising or efficient gettin there pace is what she prefers now. Hell I'm 48x16 in the winter, which feels slow after a summer of a road bike that never leaves it's 54 in front, but it does feel nice to be fixed again everyday.

The riding position is forward, it's an old Raleigh Capri, she'll be on the hoods 99.99999% of the time. I also have the forward reach of the handlebars level to the ground and the levers back a bit so she's not so stretched out. I plan to put pics up this weekend.

Gosh it's about 50/50; stay at 17 or go up to 21....