# Beginner Tire Question



## mksmith713 (Aug 27, 2011)

I'm a total newbie having just purchased my first bike about two months ago.
When I purchase my bike a few things were considered.
First, I'm shy of 5'8" and weighed 240 at the time of purchase.
Additionally, $ was an issue so road bikes weren't really an option.
The LBS tried to talk me into a MTB but I wasn't having any of that opting for a Trek 7.3 fx fitness bike.
Since that time I've been riding religiously putting in roughly 100 miles a week.
I've dropped my weight from that miserable 240# to a much nicer 180#ish.
Here's my question.....the stock Trek 7.3 fx has 700c x 32 tires (max psi is 85, I keep it at 80 Front and back).
I'm considering going with a thinner higher pressure tire to increase my speed (considering Trialthalons on this bike).
With the current tires and a nice cadence I'm averaging between 17 and 21 mph on fairly flat roads here in So. Fla.
I was curious if dropping to a 700c x 25 or 23 would increase my speed enough to justify the expense of tires and tubes.
Any input would be greatly appreciated.


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## tihsepa (Nov 27, 2008)

Yes and no on the faster part. Some 32's are really heavy tires. Going to a lighter tire will make you faster. The key is lighter not necessarily smaller. Although to get one you usually needmthe other.
A nice 25 or 28 would serve you well.


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## mksmith713 (Aug 27, 2011)

What would you consider significant weight difference?

Is my reasoning correct when I assume higher tpi means better resistance to flats but more weight?
I see most tires being either 60 or 120 tpi


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## mksmith713 (Aug 27, 2011)

According to the specs on Bontragers website, the stock tires on my bike are comng in at a whopping 510g.
The tires I'm looking at replacing them with are right about 250g.


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## TomH (Oct 6, 2008)

Its more about rolling resistance, all though lighter tires will feel much snappier. You'd appreciate a good 25c tire, would make riding more fun.


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## Mike T. (Feb 3, 2004)

TomH said:


> Its more about rolling resistance, all though lighter tires will feel much snappier. You'd appreciate a good 25c tire, would make riding more fun.


What Tom said. OP - get some 25 or 28mm high-end tires (Continental, Vittoria, Michelin etc) and inflate to the max of 100psi and I'll bet they will transform that bike. Don't forget to get tubes to match.


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## LC (Jan 28, 2004)

I would not go below 25c on that bike. Tires and wheels are usually a worthwhile upgrade.


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## Mtl_Rookie (Jul 24, 2011)

LC said:


> I would not go below 25c on that bike. Tires and wheels are usually a worthwhile upgrade.


I would have to second that.


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## mksmith713 (Aug 27, 2011)

Another thing I didn't consider before now........chainring sizes.
My bike has a triple crankset 48/38/28 with the cassette a 11-32
Any significance there that would slow me down?


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## Mike T. (Feb 3, 2004)

mksmith713 said:


> Another thing I didn't consider before now........chainring sizes.
> My bike has a triple crankset 48/38/28 with the cassette a 11-32
> Any significance there that would slow me down?


Slow you down? If you could push 48/11 (117") on the flat you'd be world class. If you're not wasting gears by having gears too low for your terrain (the 28t ring and the 26-32t cogs) then you're just fine. For instance - anything lower than a 39t ring and a 25t sprocket would be wasted metal for *me*.


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## AndrwSwitch (May 28, 2009)

If you're serious about triathlons, get a road bike. They don't have to cost much if you don't want them to. I ride a bike I bought for $95 to school. If it fit me a little better, I could swim, and I didn't hate running, I would totally clip on some aero bars and do a triathlon with it. Disliking 2/3 of the sports discourages me from doing those events, though.  The biggest source of resistance on a bike ridden on a flat road is air. And the thing that pushes the most air is the funny-looking biped on top of the bike.

tpi is Threads Per Inch. Higher tpi is usually lighter. Some people think they're not as durable but I think they're about the same, and I do think they flat less. But it's part of a more expensive tire, so everything else is nicer too. Hard to be scientific. I could swear they roll better, although I doubt I could prove it with a stop watch with a small enough standard deviation to be useful.


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## mksmith713 (Aug 27, 2011)

AndrwSwitch said:


> tpi is Threads Per Inch. Higher tpi is usually lighter. Some people think they're not as durable but I think they're about the same, and I do think they flat less. But it's part of a more expensive tire, so everything else is nicer too. Hard to be scientific. I could swear they roll better, although I doubt I could prove it with a stop watch with a small enough standard deviation to be useful.


But doesn't that defy reasoning?
More threads per inch should weigh more but offer more stability.
I've never heard of more weighing less if all factors are equal.


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## mksmith713 (Aug 27, 2011)

Unless the threads are larger in circumference and cover the same amount of space.


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## AndrwSwitch (May 28, 2009)

If I need to fit twice as many of something roughly cylindrical into the same space, they need to be half as wide. If those things are circular, the volume drops geometrically. So higher thread count means much finer threads, that each weigh a lot less than half of what the coarse ones do.

The arguments about durability are a little harder - the fine threads, individually, are less durable. Which is pretty intuitive. But they're also more supple, and there are more of them. That's where the better ride feel comes from. I think it also means the tire is more likely to conform to a piece of debris instead of being punctured, but that's just a theory - I don't know if it has any basis in reality.

Think fancy sheets.


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## Mike T. (Feb 3, 2004)

mksmith713 said:


> But doesn't that defy reasoning?
> More threads per inch should weigh more but offer more stability.
> I've never heard of more weighing less if all factors are equal.


More threads per inch = thinner threads = more supple threads = better ride.

BTW if there was ONE thread per inch it would be 1" diameter and very heavy. More threads per inch means smaller diameter threads and therefore a thinner casing therefore lighter.


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## RickJP (Aug 11, 2011)

Hi folks! Like mksmith713, I'm also a newbie. I have a Felt F85 51cm that I bought new from a local LBS (only that this LBS is about 15 miles from my home) and I have a question regarding innertube size. Looking at Amazon.com, they offer a tube with two sizes that would fit my bike. The bike has 700c x 23 tires, and the tubes offered are from 700 x 18 - 23 and 700 x 23 - 25. 

Is there any reason to pick one from the other? Why?

Thanks!!!


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## AndrwSwitch (May 28, 2009)

There are all kinds of reasons to pick one tube over another.

But if you're not competing, you just want an inexpensive butyl rubber tube with a 32mm Presta valve.

Both sizes are fine. If you get a tube that's a size or two too small, it stretches to fill the tire. Maybe it'll lose air marginally faster, but there's no other issue.

If you get a tube that's too big, you may have trouble mounting the tire and inflating the tube the first time without damaging it. If it's wildly too big, you may find you end up with the rubber folded over in places, causing a bump every rotation.

If there's a price break, buy three.


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## RickJP (Aug 11, 2011)

AndrwSwitch said:


> There are all kinds of reasons to pick one tube over another.
> 
> But if you're not competing, you just want an inexpensive butyl rubber tube with a 32mm Presta valve.
> 
> ...


Thanks Andrw.

They're both within cents of each other and your rationale makes sense. I just want to have a bit of a surplus when it comes to tubes. I figured two at home and one to carry with me when I ride.


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## JailGuard (Mar 21, 2011)

mksmith713 said:


> The LBS tried to talk me into a MTB but I wasn't having any of that opting for a Trek 7.3 fx fitness bike.
> I'm considering going with a thinner higher pressure tire to increase my speed (considering Trialthalons on this bike).
> With the current tires and a nice cadence I'm averaging between 17 and 21 mph on fairly flat roads here in So. Fla.
> I was curious if dropping to a 700c x 25 or 23 would increase my speed enough to justify the expense of tires and tubes.
> Any input would be greatly appreciated.


When I switched from my MTN bike I too went with a Trek 7.3 FX. In one year i put on over 3000 miles. I then went to a used road bike and now I purchased a 2011 Specialized Roubaix Expert. 
So when I had my FX I swapped tires after about 1500 miles. I went to a Specialized Armadillo Elite 700x28c. Made a HUGE difference.. if you want another upgrade, swap your wheelset there are plenty of lighter better rollling wheelsets out there for an inexpensive price.
just my 2 cents....


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## mksmith713 (Aug 27, 2011)

I opted to trade in my 7.3 fx and go with a Trek 1.2 entry level road bike.
Should be delivered sometime this week.


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## heybrady (Jul 3, 2011)

Good choice. You will notice a huge difference between bikes. Post it up on the beginner thread and post a review.


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## JailGuard (Mar 21, 2011)

Great to hear!!!


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## Uprwstsdr (Jul 17, 2002)

mksmith713 said:


> I've dropped my weight from that miserable 240# to a much nicer 180#ish.


You really dropped 60#'s in two months? That's impressive!


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## RickJP (Aug 11, 2011)

Uprwstsdr said:


> You really dropped 60#'s in two months? That's impressive!


Also not healthy. That's 1 pound a day when healthy weight loss should only be 2 - 3 pounds a week.

Just my .02


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## mksmith713 (Aug 27, 2011)

Healthy as an OX.
In fact, healthier than I've been in over 25 years.


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## RickJP (Aug 11, 2011)

Good for you then. Heck, 18 years ago I dropped 30 pounds in one month. When my doctor found out, he had me do a whole heck of a slew of blood tests to confirm all my counts were up to par, and I was only 31 years old at the time. 

I'm only repeating what my wife, who practices medicine, and many other medical professionals say. But, that's why we're individuals; because we're not all the same.


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