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Affects of too big cog on Fixie

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Affects of too big cog on Fixie

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Old 12-04-18, 03:19 PM
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Affects of too big cog on Fixie

What happens if I build a Fixie with 42x18 gearing? Going downhill, will my legs fall off?

This is what I run now on my coaster hub SS commuter bike.
I think I need to keep this low gearing for my commute.
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Old 12-04-18, 03:25 PM
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It will be fine.
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Old 12-04-18, 04:01 PM
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Originally Posted by mtb_addict View Post
What happens if I build a Fixie with 42x18 gearing? Going downhill, will my legs fall off?

This is what I run now on my coaster hub SS commuter bike.
I think I need to keep this low gearing for my commute.
if you literally already have this gearing, have your legs fallen off? Put a fixed cog on, go out and ride as fast as you can, down the biggest hill, then get back to us. Until then, stop with all these useless posts.
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Old 12-04-18, 04:30 PM
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Read my post more carefully please! I said I'm riding 42x18 on a coaster hub...which mean it can coast down hill. Of course anyone can ride a coaster hub with any gearing down hill.

My question is about Fixed Gear. If the bike is travelling 25 mph downhill...how fast does my leg have to spin to keep up?

And if the leg can't keep up, would one be able to unclip from the pedal?
If one cannot unclip and the pedal keeps spinning faster than the leg can move, what would happen?

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Old 12-04-18, 04:43 PM
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I've done it. You do have to pedal fast, and it's a good idea to develop a form so that your butt doesn't bounce. That's the challenge. But you'll have a front brake on the bike, right? So with that, you can scrub off the amount of speed that threatens a lost of control.
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Old 12-04-18, 05:04 PM
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Originally Posted by mtb_addict View Post
Read my post more carefully please! I said I'm riding 42x18 on a coaster hub...which mean it can coast down hill. Of course anyone can ride a coaster hub with any gearing down hill.

My question is about Fixed Gear. If the bike is travelling 25 mph downhill...how fast does my leg have to spin to keep up?

And if the leg can't keep up, would one be able to unclip from the pedal?
If one cannot unclip and the pedal keeps spinning faster than the leg can move, what would happen?
i did read it, thank you. I said “put on a fixed cog.” But you don’t need a fixed cog to test this. based on the info given in your original post, all you have to do is keep pedalling. You didn’t ask anything about speed, you asked if your legs would fall off. Since you know your legs won’t fall off, your post wasn’t in any way serious or worth a serious response. This is a pattern with your posts. You also mentioned nothing about clipless pedals. If you don’t have a brake, then the answer is you hit the pavement. That’s common sense. Maybe it’s YOU that needs to read more carefully, and give it a rest with all these unnecessary posts.

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Old 12-04-18, 05:49 PM
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Originally Posted by noglider View Post
I've done it. You do have to pedal fast, and it's a good idea to develop a form so that your butt doesn't bounce. That's the challenge. But you'll have a front brake on the bike, right? So with that, you can scrub off the amount of speed that threatens a lost of control.
I'll have a hand brake in the beginning. Once I learn to use my legs to brake, I will remove the hand brake. Hence, my thinking is how much margin of error do you have before you lose control. Like what if my legs are very tired from climbing to the top of the overpass...then when going down, my legs have no more strength to resists the pedal. I guess I can put a small interrupter-style hand brake, just in case.

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Old 12-04-18, 05:54 PM
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If losing control is even a tiny concern in your mind, that means you shouldn't be riding without brakes.
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Old 12-04-18, 07:41 PM
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Riding a fixie without a brake is stupid. Of course, that's my opinion, but I said it.

I've been riding fixed for a long time, and a few years ago, I attended a clinic for track racing at Kissena Velodrome. The teacher is a bike messenger by profession. He mentioned that messengers are harder to teach proper riding technique on the track because they brake so hard with their legs, and it's bad manners on the track. Someone raised her hand and asked how she deals with the need to stop on the streets. He said, "Very simply, I use my brake."
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Old 12-04-18, 07:52 PM
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Originally Posted by mtb_addict View Post
Read my post more carefully please! I said I'm riding 42x18 on a coaster hub...which mean it can coast down hill. Of course anyone can ride a coaster hub with any gearing down hill.

My question is about Fixed Gear. If the bike is travelling 25 mph downhill...how fast does my leg have to spin to keep up?

And if the leg can't keep up, would one be able to unclip from the pedal?
If one cannot unclip and the pedal keeps spinning faster than the leg can move, what would happen?
Your feets will not unclip by itself if you tension correctly and its not worn out clips.

If going downhill make your legs outspin and unclip by itself, you lose control and don't have brake on it.

Use your feets to rub rear tire (not the wheel itself or you risks break wheel spoke) and act it like conventional rim brake.

Your shoes probably blow out though if you don't mind trashes it after ride.

AKA seriously, if you can't take full control of it, put brake on.

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Old 12-04-18, 07:53 PM
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42x18 is low. I think it is too low for a noobie that can't spin yet.

Keep your ****ing brake. It takes a couple years of frequent, perhaps daily, fixed gear riding to get proficient with the bike handling skills necessary to not hurt yourself if you choose to go brakeless.

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Old 12-04-18, 08:57 PM
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To get back to the original question, "Affects of too big cog on fixie", lemme drop some knowledge on ya, son.

A lot of these replies are trying to confuse the issue with talk about "gear ratios" and all that technical ish. Don't fall for it.

Real talk, you bring up a good point and a got damn valid concern. And here's the scoop - too big of a cog is a HUGE issue when tearing ish up on your sw8 fixie. Follow me here - when things get bigger, what do they do? That's right, they WEIGH MORE. You get all crazy and put something bigger than a 19t cog on that rear hub and you are playing with fire my friend, throwing the weight balance into disequilibriumisation like that. Do you want your bike to fall over on it's drive side from all that excess heft? Hell no you don't.

True story - buddy of mine bought a 22t cog for his sw8 a** Bigshot fixie (green grips, orange deep deep deep V's, thing of beauty), and was all stoked to shred but then reality swooped in like the fickle b**** she is. Dude was so proud when he threaded that glorious stamped steel onto the hub, I'll never forget that. Used his best pipe wrench and everything to torque the lock ring down. Soon as he was done tho, the bike fell over hard to the right, and to this very day, the damn thing is still lying there in his garage, drive side down, and no one can even stand that sweet beautiful ride up anymore. We tried, bribed a whole bunch of friends (who can say no to ice cold Natty Light, amirite?) to help us try to pick it up but at the end of the day... that cog was just too big. I know I gave it my best, but damn if I don't still got the hernia scar that will haunt me to my grave.

Moral of the story? Small cogs are your friend amigo. Ain't nobody got time for the pain and hassle of a too big cog.

Peace

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Old 12-04-18, 09:28 PM
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Originally Posted by j_e_r_e_m_y View Post
To get back to the original question, "Affects of too big cog on fixie", lemme drop some knowledge on ya, son.

A lot of these replies are trying to confuse the issue with talk about "gear ratios" and all that technical ish. Don't fall for it.

Real talk, you bring up a good point and a got damn valid concern. And here's the scoop - too big of a cog is a HUGE issue when tearing ish up on your sw8 fixie. Follow me here - when things get bigger, what do they do? That's right, they WEIGH MORE. You get all crazy and put something bigger than a 19t cog on that rear hub and you are playing with fire my friend, throwing the weight balance into disequilibriumisation like that. Do you want your bike to fall over on it's drive side from all that excess heft? Hell no you don't.

True story - buddy of mine bought a 22t cog for his sw8 a** Bigshot fixie (green grips, orange deep deep deep V's, thing of beauty), and was all stoked to shred but then reality swooped in like the fickle b**** she is. Dude was so proud when he threaded that glorious stamped steel onto the hub, I'll never forget that. Used his best pipe wrench and everything to torque the lock ring down. Soon as he was done tho, the bike fell over hard to the right, and to this very day, the damn thing is still lying there in his garage, drive side down, and no one can even stand that sweet beautiful ride up anymore. We tried, bribed a whole bunch of friends (who can say no to ice cold Natty Light, amirite?) to help us try to pick it up but at the end of the day... that cog was just too big. I know I gave it my best, but damn if I don't still got the hernia scar that will haunt me to my grave.

Moral of the story? Small cogs are your friend amigo. Ain't nobody got time for the pain and hassle of a too big cog.

Peace
Didn't it end up damaging the concrete flooring as well?
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Old 12-04-18, 09:34 PM
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Originally Posted by mouse View Post
Didn't it end up damaging the concrete flooring as well?
You don't know the half of it. Dude's garage foundation was just WRECKED. It's a miracle it's still standing.
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Old 12-04-18, 09:43 PM
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Oy.
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Old 12-05-18, 01:59 AM
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Old 12-05-18, 07:22 AM
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42/18 is fine, I rode that for a while in college, but with a front brake. I wanted a 17t (which is my low gear now) but the shop didn't have any so I settled for a 18t and it worked fine. I'm about to head for for ~55 mi on the Wabi before work on my "big" gear of 42/15, which might feel like too big a cog when I'm descending Torrey Pines, but that's the nature of the beast.
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Old 12-05-18, 08:00 AM
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By "big" do we mean big or do we mean small?

Are we talking about too big as in diameter of the sprocket or too big as in gear ratio?

Does "too big cog" mean too high or too low?

What, exactly, does "big cog" mean?
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Old 12-05-18, 08:06 AM
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Originally Posted by TimothyH View Post

What, exactly, does "big cog" mean?
Ohhhhhh no you didnnnnnnt
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Old 12-05-18, 09:38 AM
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I prefer an 18 up front and 42 in the back but that's just me

Still going backwards... I started out with no brake but only rode my FG on wide open gravel dike systems that are pretty flat and gradually learned to brake using my legs on small rollers. Sometimes I would have to get off and walk down a few steeper sections. Then I ventured out onto the farm roads with small hills and then I put a front brake on to start exploring further afield. So, as my skill and desire for variety improved - I put a brake on. I didn't learn how to ride with a brake and then take it off.

Jeremy: All I can think is how many cubic yards of concrete it's going to take to level off that garage floor so the bike no longer shows and someone can park in there again. Did anyone try holding the bike and walking in circles to unscrew it from the cog?

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Old 12-05-18, 10:33 AM
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Personally, I was so worried about the dangers of riding a fixed-gear bike with no brakes, I went in the opposite direction: I built up a bike with two brakes and no gears.

While it does take a lot more work to keep moving, it's great exercise and it's a lot safer. I do find I have to replace shoes more frequently, but at the same time, I've never fallen over because I couldn't unclip from the pedals.
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Old 12-05-18, 04:15 PM
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Old 12-05-18, 05:54 PM
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for every pedal stroke you will travel 62 imaginary inches on your imaginary fixieeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

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Old 12-05-18, 06:00 PM
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Originally Posted by mtb_addict View Post
Read my post more carefully please! I said I'm riding 42x18 on a coaster hub...which mean it can coast down hill. Of course anyone can ride a coaster hub with any gearing down hill.

My question is about Fixed Gear. If the bike is travelling 25 mph downhill...how fast does my leg have to spin to keep up?
≈137rpm on 700x23
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Old 12-05-18, 06:06 PM
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137 rpm isn't that fast. I think I have hit 180 rpm going downhill.
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