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New Freewheel?
#1
I'm getting my bike ready for the riding season here and I had a question for Alex or the forum. I currently ride a mountain style bike that I use primarily as a commuter with some occasional recreational riding. I'm looking to increase my overall top speed. I have already changed my crank-set from a 22/32/42 to a 28/38/48, which has helped. I'm also planning on swapping my knobbies for a set of Schwalbe Marathons, 26X1.5. What I was wondering is... Would it be worth the trouble to change my freewheel? My current top gear is 14 teeth and I 'd like to go taller. The only taller gear freewheel I've been able to find has a 13 tooth top gear. Would one tooth make any noticeable difference? Also, if anyone knows where to find an 11 tooth top gear freewheel I'd appreciate the location. Thanks in advance for any info.

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#2
It would make a small difference but in all honesty it wouldn't justify the cash spent on it as you'd be shedding only a fraction of a second off for about £10-15 ($20-30, but I suspect components are cheaper in the States than in the UK). You'd be better off trying to shed some weight from the bike by installing tyres with a lower rolling resistance (which you appear to have done) or installing lighter components.
Or just simply make sure everything is properly greased and cleaned.

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#3
Going from a 14 to 13 sprocket would be about 7%.
So at 20mph you would gain 1.4 mph = 21.4 ?
Are you running out of rev's?

[font=Trebuchet MS]Ride hard or ride home alone![/font]
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#4
Yes, I've pretty much reached my spinning limit. I'm basically looking to achieve 30-35mph on the flats in order to keep up with the flow of traffic. I'm not sure that's possible, but it's a goal I have.

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#5
Quote:I'm basically looking to achieve 30-35mph on the flats in order to keep up with the flow of traffic. I'm not sure that's possible, but it's a goal I have.
The average top speed of the winner of the 2008 Tour De France was 25 mph... so I get the distinct feeling that ain't happening. If you look comparatively to the kinds of athletes that do this, you might be doing pretty well with where you're at.
(not trying to be snotty, just trying to add some perspective to this statement.)

Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
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#6
Look at the speed that you do now and work out the percentage increase you need.
Then multiply the ratios up.
30 - 35 mph is obtainable but not for very long.
Very fit time trialists will do 25 miles in minimum of 50 minutes and 10 miles in about 19 minutes. (~ 30mph). And that is in an aerodynamic position.

[font=Trebuchet MS]Ride hard or ride home alone![/font]
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#7
I'm guessing Binzer isn't riding thousands of miles, so the Tour comparison isn't very applicable. But 30-35 is very fast. Regardless, I think the point is that you want to go faster, but your bike is topping out due to the gearing, etc. Note that there is a difference between changes that make it easier to go faster (slick tires) and changes that allow for a higher top speed, assuming a limit on how fast you can spin the pedals.
Besides the limitation of gearing designed for mtn bikes, there is also the problem of wheel size. Given the same gear ratio on a road and mtn bike, the road bike goes faster at the same pedal rotation because each rotation of the (larger diameter) wheel covers more distance. The narrower, higher pressure, tires and drop-bar riding position also make it easier to go faster due to less rolling and wind resistance. It is possible on some mtn frames to fit 700c wheels. Though it takes some tinkering and you'd need new brakes. I've also done drop bar on mtn bike conversions, but that also takes some tinkering on brakes and gear shifters.
At the end of the day, if you really like going fast, you need a road bike. It's the right tool for the job. Don't waste a lot of money trying to make an off road bike do what a road bike is designed for. Start saving up your money to get the bike you want.

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#8
I'm guessing Binzer isn't riding thousands of miles, so the Tour comparison isn't very applicable. But 30-35 is very fast.
It's the best statistical comparison I could cook up quickly given that the statement sounded a bit suspicious. As we know, the 25mph figure is done by trained athletes on road bikes, as you well pointed out, how much more not possible is this going to be on a MTB.
I second that, if you're really wanting speed, a road bike's going to be pretty much the only option.

Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
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#9
I appreciate all the input folks. Allow me to clarify the "30-35mph" statement. It's on some of the flats and downhill segments of my commute, not a constant speed. I've ridden a road bike in the past and for a commuter, in my area at least, it's not the best choice. Rough roads and debris make it hard on the bike, so a mountain style bike is a better choice for me. I have reached a top speed of 38mph on some long downhill stretches by the way, but I peak at rpm's. I'm not looking to win any races here though, just pick up a bit of speed and cut my commuting time.

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#10
Changing to 1.5 slicks on my old MTB has really allowed me to go faster so I would replace those and see how things work before you change anything else. That would be the easiest and cheapest option for you.

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#11
Schwalbe slicks are great tires. They will definitely increase your average speed (though not your top speed if what is limiting you is pedal revs). Probably safer too. I wouldn't want to go close to 40 mph on knobbies.
The only ways to address the top speed issue is higher gears or larger wheels. It depends on what kind of freewheel you have now, but you may be able to get one with a 12t small cog. You will definitely feel the difference between that and the 14t. (14% higher gear). Shimano used to make an 11t freewheel, but I think you cannot get them anymore. Only 11's I've seen are on certain cassettes.
You can adapt a road triple crankset to a mtn bike which might get you up to a 52 or even 53 tooth in the front. But changing to 12t in the back is a bigger change for probably lower price.

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#12
I appreciate all the tips folks. DaveM, I'll keep an eye out for the 12t small cog freewheel. If anyone else should happen to see one I would appreciate knowing where to get one.

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#13
How about looking out for a second set of wheels ( or just a back wheel)
Get a set with a cassette then you can chose any rear gears that you want.
You will though have to take into account your gear changer.
The number of gears shouldn't be a problem but the indexing may be if your changer is indexed?
Most Shimano "freehubs" will take 6,7,8 or 9 sprockets.
6 / 7 sprockets generally need spacers to make up for the missing gears.

[font=Trebuchet MS]Ride hard or ride home alone![/font]
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#14
I took at look at some wheelsets and to be honest, the price is a bit high. I guess I'll make due with what I have right now and keep an eye out for the smaller cog freewheel. I also may consider getting a different bike. I've been looking at a Gary Fisher "Kaitai". It seems to have most everything I'm actually looking for. Thanks again everyone for all the suggestions.

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