Gears/Gear ratio?????Help

[mikesbytes]

There has been no scientific study, I know of, that has shown any difference in performance vs crank arm length, from the Std. 172.5mm crank arm, except for some very tall and heavy pro riders and those tests were not repeatable. I would recommend a 34-50 crankset with a 12-25 cassette if it is 10 speed Campagnolo or 12-27 if it is 10 speed Shimano. This gives you a a higher high gear than your example. With the 12 x 50, you are spinning 122rpm @ 40mph vs your 127rpm. For the low gears, both my examples give you a lower gear than your 25x39 example, or even a 27-39.

Hi lks, this is what sheldonbrown has to say about crank lengths: http://www.sheldonbrown.com/gain.html

The longer the leaver the easier it is to push, however your legs have to travel further, so you can't turn them as quickly, ie you have a slower maximum rpm.

Criag needs to give more details on what kind of riding he does, before a gearing recommendation can be given.

BTW, why are you recommending different gearing for Campagnolo to Shimano.

 

[lks]

Hi lks, this is what sheldonbrown has to say about crank lengths: http://www.sheldonbrown.com/gain.html

The longer the leaver the easier it is to push, however your legs have to travel further, so you can't turn them as quickly, ie you have a slower maximum rpm.

Criag needs to give more details on what kind of riding he does, before a gearing recommendation can be given.

BTW, why are you recommending different gearing for Campagnolo to Shimano.

Theory is only as good, as scientific proof/tests confirm it. If you have scientific pro rider TEST data on different crank arm lengths, post it. The lowest cog for a 10 speed Shimano 105. Ultegra and Dura-Ace, is a 27t. For Camagnolo's equivalent, It's their 12-25. You can go to their 13-26 but you gain almost nothing over the 25t and sacrafice a lot with the 13t. You can go to their 13-29, but you have to use a medium length rear dearailleur cage. If Campy made a 12-27, that would work with their short cage derailleur, I would buy it tomorrow regardless of price.

 

[lks]

Hi lks, this is what sheldonbrown has to say about crank lengths: http://www.sheldonbrown.com/gain.html

The longer the leaver the easier it is to push, however your legs have to travel further, so you can't turn them as quickly, ie you have a slower maximum rpm.

Criag needs to give more details on what kind of riding he does, before a gearing recommendation can be given.

BTW, why are you recommending different gearing for Campagnolo to Shimano.

Many frames today, require a chainline that places the inside ring gear very close to the chain stay. Because the chain stay angles outward, an increase in crank arm lenght could cause interference between the chain stay and inside ring gear and/or shoe heel. It also decreases the distance between the shoe toe and front wheel, which may cause "toe overlap". In any event, this should be checked out before buying longer crank arms.

 

[Bro Deal]

It also decreases the distance between the shoe toe and front wheel, which may cause "toe overlap".

No one should worry about toe overlap. It is normal for small frames with a short wheel base.

As you posted earlier, there is no solid basis for choosing a shorter versus a longer crank. It all seems to be made up of myth, old wives tales, and B.S. Keith Bontrager has an essay floating around somewhere with is thoughts on the subject. It can probably be found with google.

I tend to think that a longer crank will benefit a masher and a shorter crank will benefit a spinner, but that is just a guess. The 172.5 is only one and a half percent longer that the 170 so I am not sure what amount of difference it would really make and whether it would be consistently measurable.

 

[xxamr_corpxx]

If you're just starting out and are comparatively weak (like me), get a triple chainring installed - it's easier to spin than mash for now.

I switched my 52-42 chainring for a 48-38-28 chainring. Now I can finally climb any hill I desire.

 

[peet9471]

Cadence is more important than ratio at this point. Start out on an easy ride with the rear derailuer set in the middle of the gears. Count the number of revolutions per minute of either foot. (I count for 15 sec. and multiply by 4) It should be between 60 (beginner) and 120 (pro). Try to establish a norm. If you fall behind (say down to 55) try the next larger rear gear to get you back up to 60. If you start to go down a hill, switch to a larger front chain ring, but keep counting your cadence. After you can consistantly ride all day at 60 (maybe a month) try 70. You will probably max out before you get to 120, but only you will know. After about a year, if you find yourself not able to reach your normal cadence, you will have enough experience to talk to guys at the local bike shop about your wants and needs. Until then, happy riding.

 

[mikesbytes]

No one should worry about toe overlap. It is normal for small frames with a short wheel base.

Agree, in 4 years, I still didn't wear thru the toe of the shoe from wheel rub.

As you posted earlier, there is no solid basis for choosing a shorter versus a longer crank. It all seems to be made up of myth, old wives tales, and B.S. Keith Bontrager has an essay floating around somewhere with is thoughts on the subject. It can probably be found with google.

Interesting. Doesn't the laws of leaverage apply? The longer the leaver, the less force needs to be applied. If you find the essay, can you post a link?

I tend to think that a longer crank will benefit a masher and a shorter crank will benefit a spinner, but that is just a guess. The 172.5 is only one and a half percent longer that the 170 so I am not sure what amount of difference it would really make and whether it would be consistently measurable.

Yes long cranks for mashers and short cranks for spinners.

Anyway, I think we have done the crank length thing to death on this thread.

cmdukes, peet9471's post is good advice on what gear to select.

 

[lks]

No one should worry about toe overlap. It is normal for small frames with a short wheel base.

As you posted earlier, there is no solid basis for choosing a shorter versus a longer crank. It all seems to be made up of myth, old wives tales, and B.S. Keith Bontrager has an essay floating around somewhere with is thoughts on the subject. It can probably be found with google.

I tend to think that a longer crank will benefit a masher and a shorter crank will benefit a spinner, but that is just a guess. The 172.5 is only one and a half percent longer that the 170 so I am not sure what amount of difference it would really make and whether it would be consistently measurable.

One of us is confused about what "toe overlap" is. Experts say it is when your toe overlaps the tire, preventing it from turning and/or deflecting the front wheel when you get out of the saddle and sprint. It can be, and has been, dangerous.

 

[gclark8]

Maybe your wheels are too big,

600mm seat height, 24" wheels, 152-155mm cranks,
650mm seat height, 26"/650c wheels, 160-165mm cranks,
700mm seat height, 700c wheels, 170-175mm cranks,

GO!

 

[Bro Deal]

One of us is confused about what "toe overlap" is. Experts say it is when your toe overlaps the tire, preventing it from turning and/or deflecting the front wheel when you get out of the saddle and sprint. It can be, and has been, dangerous.

No it is not, and no experts say this. Toe overlap only comes into play with the bars turned considerably. The bar angle required is not possible during regular speed; you would instantly crash if you turned the bars the required amount while actually riding. You only run into toe overlap during tight turns at very, very low speed, think doing a U-turn in ten or twelve feet, and it is easy to avoid touching your tire with your shoe; you simply avoid putting the crank arm on the outside of the turn in the 3 O'Clock position during the tightest part of the turn.

As I stated above, toe overlap is normal with a small framed racing bike, which typically have short wheelbases.

 

[lks]

No it is not, and no experts say this. Toe overlap only comes into play with the bars turned considerably. The bar angle required is not possible during regular speed; you would instantly crash if you turned the bars the required amount while actually riding. You only run into toe overlap during tight turns at very, very low speed, think doing a U-turn in ten or twelve feet, and it is easy to avoid touching your tire with your shoe; you simply avoid putting the crank arm on the outside of the turn in the 3 O'Clock position during the tightest part of the turn.

As I stated above, toe overlap is normal with a small framed racing bike, which typically have short wheelbases.

Buy a bike/frame that fits you and doesn't have toe overlap. Don't buy a bike/frame with toe overlap because it requires you NEVER ONCE FORGET the riding conditions that will put you on your nose. Manufacturers make frame sizes that don't require toe overlap. The tecnical editor of Velo news say's, " Toe overlap is to be AVOIDED because it can put you on your nose". Viewers can take your advice or Lennard Zinn's of Velo News! Caveat Emptor!

 

[Bro Deal]

Buy a bike/frame that fits you and doesn't have toe overlap. Don't buy a bike/frame with toe overlap because it requires you NEVER ONCE FORGET the riding conditions that will put you on your nose. Manufacturers make frame sizes that don't require toe overlap. The tecnical editor of Velo news say's, " Toe overlap is to be AVOIDED because it can put you on your nose". Viewers can take your advice or Lennard Zinn's of Velo News! Caveat Emptor!

Once again you are spouting off about things you know nothing about and acting like an expert while doing it. You want experts, take these:

Sheldon Brown:

"On many bicycles, especially smaller sizes, it is possible for the front fender or tire to bump into the rider's toe or to the toe clip. Some people worry a lot about this, but it is rarely a significant problem in practice. The only time it can happen is when the handlebars are turned quite far to the side, which only happens at very low speeds.

Many, many people ride bikes with fairly severe overlap with no practical problems, sometimes having to make a slight adjustment to their pedaling habits at very slow speeds.

On smaller size bikes with full size wheels, it is usually impossible to eliminate overlap without causing adverse fit/handling issues."


How about Bernard Hinault. Heard of him? In his book he says not to worry about toe overlap when choosing a frame.


How about Seven Cycles:

"Understanding Toe Overlap

Toe overlap is an often misunderstood phenomenon that refers to the tip of your shoe touching or overlapping your bike's front tire under one relatively rare and specific circumstance: If your feet are positioned at 3:00 and 9:00 and you simultaneously turn your front wheel sharply in the direction of your forward foot--the one positioned at 3:00--while riding at very low speed. Toe overlap is not a flaw in the bike's design. In fact, it exists on many of road bikes. The reason and extent to which it exists relates to frame geometry and the choice of components.

What is the tradeoff of designing a bike specifically to eliminate toe overlap?

At Seven, optimized performance and predictable handling are the primary drivers of our frame design philosophy. Our view is that high-speed handling and safety is more important than the potential risk toe overlap presents in your driveway or parking lot. So if instead we were to design a frame around the specific goal of eliminating toe overlap, the bike's handling could become less predictable and even potentially dangerous. Remember, toe overlap is only an issue under one specific and avoidable circumstance. By contrast, poor handling resultant from compromising a frame's design will always be a factor when you ride.

The reason toe overlap is only a consideration at very slow speeds is that if you tried to turn your front wheel sharply at higher speeds, you would likely crash before your shoe had a chance to touch your front wheel. Steering a bike takes very little effort; it's a matter of adjusting your body weight an gently turning your front wheel slightly. Turning the front wheel sharply under any circumstances is dangerous"


Mark Hickey, owner and designer of Habenero Cycles:

"It's almost impossible to build a smaller bike with no
possibility of toe overlap, without making some truly awful
compromises in the handling of the bike....I've found that
toe overlap really isn't a big deal on a road bike. Really, all
you have to do to overcome it is to experience it a couple
times in a controlled environment (i.e. practice very slow
turns). You quickly learn to either turn away from the interference
point for a split second, or to simply drop your heel for a moment."


I could go on. Instead of trying to pretend like you are an expert by referring to other "experts" why don't you actually address the points I have made. Specifically:

1) Toe overlap does not cause a problem because you cannot turn the front wheel sharply enough to actually touch your shoe while riding at speed.

2) Toe overlap only happens during very low speed while doing things like making a very tight U-turn or nearly trackstanding, and it is easy to avoid having any problem due to toe overlap.

3) Toe overlap is common on small framed racing bikes with 700c wheels, which typically have short top tubes, steep head angles, small fork rake, and short wheelbases. I'll also add that toe overlap is not uncommon on bikes with aggressive geometry up to 55 and 56 cm and beyond, especially if the rider has big feet.

If you want a fourth point here's one:

4) Toe overlap does become a problem on mountain bikes where low speed maneuvers are common, and psuedo-experts on the Internet should not confuse advice given about mountain bikes with advice suitable for road racing bikes.

 

[mikesbytes]

I have toe overlap on both my road bike and my track bike and it is not a concern. You will never touch your tyre during a sprint as the wheel isn't turned that much.

I do touch my toe when commuting, where I am doing what is effectivily a u-turn on a tight corner of a bike path. All that happens is that the toe rubs the tyre and thats it. The most significant issue is that you have a mark on your nice clean shoes.

 

[lks]

Once again you are spouting off about things you know nothing about and acting like an expert while doing it. You want experts, take these:

Sheldon Brown:

"On many bicycles, especially smaller sizes, it is possible for the front fender or tire to bump into the rider's toe or to the toe clip. Some people worry a lot about this, but it is rarely a significant problem in practice. The only time it can happen is when the handlebars are turned quite far to the side, which only happens at very low speeds.

Many, many people ride bikes with fairly severe overlap with no practical problems, sometimes having to make a slight adjustment to their pedaling habits at very slow speeds.

On smaller size bikes with full size wheels, it is usually impossible to eliminate overlap without causing adverse fit/handling issues."


How about Bernard Hinault. Heard of him? In his book he says not to worry about toe overlap when choosing a frame.


How about Seven Cycles:

"Understanding Toe Overlap

Toe overlap is an often misunderstood phenomenon that refers to the tip of your shoe touching or overlapping your bike's front tire under one relatively rare and specific circumstance: If your feet are positioned at 3:00 and 9:00 and you simultaneously turn your front wheel sharply in the direction of your forward foot--the one positioned at 3:00--while riding at very low speed. Toe overlap is not a flaw in the bike's design. In fact, it exists on many of road bikes. The reason and extent to which it exists relates to frame geometry and the choice of components.

What is the tradeoff of designing a bike specifically to eliminate toe overlap?

At Seven, optimized performance and predictable handling are the primary drivers of our frame design philosophy. Our view is that high-speed handling and safety is more important than the potential risk toe overlap presents in your driveway or parking lot. So if instead we were to design a frame around the specific goal of eliminating toe overlap, the bike's handling could become less predictable and even potentially dangerous. Remember, toe overlap is only an issue under one specific and avoidable circumstance. By contrast, poor handling resultant from compromising a frame's design will always be a factor when you ride.

The reason toe overlap is only a consideration at very slow speeds is that if you tried to turn your front wheel sharply at higher speeds, you would likely crash before your shoe had a chance to touch your front wheel. Steering a bike takes very little effort; it's a matter of adjusting your body weight an gently turning your front wheel slightly. Turning the front wheel sharply under any circumstances is dangerous"


Mark Hickey, owner and designer of Habenero Cycles:

"It's almost impossible to build a smaller bike with no
possibility of toe overlap, without making some truly awful
compromises in the handling of the bike....I've found that
toe overlap really isn't a big deal on a road bike. Really, all
you have to do to overcome it is to experience it a couple
times in a controlled environment (i.e. practice very slow
turns). You quickly learn to either turn away from the interference
point for a split second, or to simply drop your heel for a moment."


I could go on. Instead of trying to pretend like you are an expert by referring to other "experts" why don't you actually address the points I have made. Specifically:

1) Toe overlap does not cause a problem because you cannot turn the front wheel sharply enough to actually touch your shoe while riding at speed.

2) Toe overlap only happens during very low speed while doing things like making a very tight U-turn or nearly trackstanding, and it is easy to avoid having any problem due to toe overlap.

3) Toe overlap is common on small framed racing bikes with 700c wheels, which typically have short top tubes, steep head angles, small fork rake, and short wheelbases. I'll also add that toe overlap is not uncommon on bikes with aggressive geometry up to 55 and 56 cm and beyond, especially if the rider has big feet.

If you want a fourth point here's one:

4) Toe overlap does become a problem on mountain bikes where low speed maneuvers are common, and psuedo-experts on the Internet should not confuse advice given about mountain bikes with advice suitable for road racing bikes.

How about your expert opinion on a real world typical application? My 56cm top tube frameset, with 172.5 cranks and 700x23 tires, is a no compromise fit. Verified by a visiting team member my size from Francais des Jeux. I have no toe overlap, even with 9 degree float cleats, but it's close. But I wear size 7 shoes. If I wore size 9 or bigger, I would get toe overlap at only a 7 foot radius/14 foot turning circle, not exactly tight. If that was the case, would you advise just learning to live with it or going to a 57cm top tube and 1cm shorter stem?

 

[Bro Deal]

How about your expert opinion on a real world typical application? My 56cm top tube frameset, with 172.5 cranks and 700x23 tires, is a no compromise fit. Verified by a visiting team member my size from Francais des Jeux. I have no toe overlap, even with 9 degree float cleats, but it's close. But I wear size 7 shoes. If I wore size 9 or bigger, I would get toe overlap at only a 7 foot radius/14 foot turning circle, not exactly tight. If that was the case, would you advise just learning to live with it or going to a 57cm top tube and 1cm shorter stem?

I am not an expert, but I do have a lot of real world experience with toe overlap, which due to your small feet you do not. I am right on the borderline and half my bikes have toe overlap.

I would advise exactly what I have been saying: Toe overlap does not matter. So changing frame size or geometry to avoid it is silly. Worrying about falling over at walking speeds and slower because of toe overlap is like worrying about falling over because of clipless pedals. Sure newbies fall over because of clipless pedals, but it only takes one or two incidents before they learn not to. The same is true of toe overlap--maybe less true since a lot of riders have bikes with toe overlap and never notice it and merely brushing your shoe with your front tire is not guaranteed, or even very likely, to cause you to fall unless you freak out.

 

[fauxpas]

It also decreases the distance between the shoe toe and front wheel, which may cause "toe overlap".

I am on 165mm cranks and already get toe overlap. Not that it bothers me though, due to my riding style. I never pedal with my front wheel on that acute angle...