MTB slicks thread...

[danielhaden]

You guys won't believe this, but Schwinn blackwall cruiser tires $15 ea run easily at a constant pace of 20 miles per hour. I mean, it is very easy. I aired up mine to 60 (back) and 47 (front) after finding out that Pacific rated them safe to 65 pounds pressure (despite the label on the tire).

Wet traction? Hasn't slid yet! No sliding on paint stripes, no sliding on wet railroad tracks, no sliding on wet muddy tree roots. . .Yeah. No sliding.

Broken glass? Never a problem.

Does it work in deep mud? Well, it will dig out plenty of it, but really deep mud isn't too compatible as it tries to hurl the mud. The tires are designed to float gracefully over sand and they do just fine there and on dense loose gravel.

Did it work on a mountain bike trail ride? You bet it did. That is, after I had to wait for everybody else to arrive (only about a minute or so).

There's a slight difference from the knobbies in that these can really bounce high if you hit a big enough rock.

So, if you've got some rough stuff to hit and still want to go fast. . .Schwinn blackwall cruiser tires . . .

Notes:
At 50 to 60 pounds, the outside perimeter of the tire is the same or larger than a 700c.

If you put too much air into the front tire, it won't flex and this will actually increase rolling resistance. Let just enough air out to create a slight bulge.

Absorbing/softening the strike force from bumps in the road actually makes the tire faster than if it were just rigid.

As it turns out, the huge black Schwinn Typhoon tires work great on an extremely rigid or heavy bike, while the Tom Richey 1.4 slicks work well on the full suspension bikes (except for traction, of course).

 

[gclark8]

Anyone seen any 24x1->1.5 slicks around??

Nothing in stock at Conti or Apollo (AirPro).

 

[danielhaden]

Small racing slicks? Oh yeah, recumbent tires.

You'll find those here:

http://www.easystreetrecumbents.com/stuff/tires.html

Whoops! Be sure to check your wheel size in millimeters!

I'm not sure if those particular Panaracers will fit, but Panaracer likely makes some that do fit.

 

[gclark8]

Thanks for the reply, the Panaracers would be a little narrow for this application. She ended up with 24x1.75 city slicks from BikeCorp "VT421S" 40-65psi, they should do Ok for a shopping bike. She has a Felt F100 650c for serious rides..

 

[robalert]

You guys won't believe this, but Schwinn blackwall cruiser tires $15 ea run easily at a constant pace of 20 miles per hour. I mean, it is very easy. I aired up mine to 60 (back) and 47 (front) after finding out that Pacific rated them safe to 65 pounds pressure (despite the label on the tire).

Wet traction? Hasn't slid yet! No sliding on paint stripes, no sliding on wet railroad tracks, no sliding on wet muddy tree roots. . .Yeah. No sliding.

Broken glass? Never a problem.

Does it work in deep mud? Well, it will dig out plenty of it, but really deep mud isn't too compatible as it tries to hurl the mud. The tires are designed to float gracefully over sand and they do just fine there and on dense loose gravel.

Did it work on a mountain bike trail ride? You bet it did. That is, after I had to wait for everybody else to arrive (only about a minute or so).

There's a slight difference from the knobbies in that these can really bounce high if you hit a big enough rock.

So, if you've got some rough stuff to hit and still want to go fast. . .Schwinn blackwall cruiser tires . . .

Notes:
At 50 to 60 pounds, the outside perimeter of the tire is the same or larger than a 700c.

If you put too much air into the front tire, it won't flex and this will actually increase rolling resistance. Let just enough air out to create a slight bulge.

Absorbing/softening the strike force from bumps in the road actually makes the tire faster than if it were just rigid.

As it turns out, the huge black Schwinn Typhoon tires work great on an extremely rigid or heavy bike, while the Tom Richey 1.4 slicks work well on the full suspension bikes (except for traction, of course).

Continental Grand Prix 26x1....

 

[danielhaden]

Transportation and safety data yields the following information:

Minimum tire size to safely navigate gravel, sand, or rough pavement:

26" wheel: 1.375 inches wide (Tom Ritchey slick 1.4)
So, it's a 1.4" tire or a broken head.
Daniel's guess for city/touring use = 1.3"

650B wheel: 1.32 inches wide (35mm)
So, it's a 1.3" tire or a broken head
Daniel's guess for city/touring use = 1.25"

700C wheel: 1.26 inches wide (700x32)
So, it's a 1.25" tire or a broken head.
Daniel's guess for city/touring use = Rivendale 700x28mm

So there you've got the statistical data on minimum tires for gravel and my guess on minimum tires for pavement. Smaller than this and you quadruple your chances of having a smaller number of working body parts.

 

[danielhaden]

The optimal air pressure has nothing to do with whatever is printed on the side of the tire.

Bumps on the road (road shock) pushes your bicycle backwards. Too much air pressure increases this force--especially for the front tire. Suspension forks double the backwards force (the force against you).

Large tires, including large slicks like Michelin Worldtour 1.2, Schwinn Typhoon, and Big Apple have ridiculously low max ratings on the side of the tire. With good wheels, these will all stand 65 pounds max. They're not as fast as skinny tires that can stand much more air, but the larger tires decrease injury statistics by over 495%.

Knobby tires do not qualify for these statistics because they ride on tiny jagged bits of rubber that have very little road traction. Bicycles have rounded contact points and cannot hydroplane even if your tire is bald. Unless you like getting muddy, the dumpster is the place for the knobbies.

At the same air pressure, large slick tires have far less rolling resistance than small slick tires--good news for rough surface riders or for those who want a fast bike that is still able to conquer the rocks.

Proper air pressure for speed does have a slight bulge at the bottom of both the front and back tires. If you put in too much air, this negates the pneumatic effect and causes the slightest bumps in the road to have a big force pushing your bike backwards.



To get the right amount of tire bulge for extra speed:

Find a yardstick, and find a wall with a flat surface next to it.

Air the tires up to the recommended amount.

Put the bicycle next to and leaning against the wall.

Put the yardstick down by the tires and paralell with the wheel. You will view the yardstick's straight edge and compare it with the edge of your tire at the bottom, so put it close to the tire.

Sit on the bicycle with it straight up and hold onto the wall for support.

If the bottom edge of the front tire is perfectly paralell with the ruler, it will be a very slow tire. Decrease the air pressure a little bit at a time until a slight bulge appears. You only need a slight bulge--while sitting on the saddle in your normal riding position. That's why you're against a wall, so that you can sit on the saddle and hold the bicycle straight up.

Now move the yardstick to paralell and up next to the rear tire. Did I mention that the yardstick IS sitting on the ground next to the tire. Well, that's where the bulge is supposed to be. If you have a large bulge in your rear tire, you might be able to increase the air pressure by 10%, but don't go above 65 pounds for tires larger than 1.6" wide.

Anyway, we're after a slight bulge for both tires. We're also comparing the side of the tire with a ruler because we want a VERY slight bulge for fast performance.

If you are lightweight, your tires will require much less air than a heavy rider. Don't be surprised if you come up with 65 in the back and barely over 40 in the front. This is enough air to prevent the tire from squirming.

Properly inflated for your body weight (by sitting on the bike and visually comparing the side of the tire against a ruler) and your riding position (sit normally on the bike), your tires will give you a far faster ride by absorbing the shock force from the road.

It's the difference between having a 7 foot long shock absorber (proper inflation) or just riding on the rims (too much air).

 

[danielhaden]

We're all tempted to try handlebars that are a little more narrow to decrease road resistance.

A big man could be pretty happy with the 25" or larger monster handlebars that come with the average mountain bike.

However, the 160 pound cyclist might prefer the 23 to 21 inch sizes.

There's no reason to have handlebars wider than your shoulder.

Transportation and safety reports yield that 23" is a minimum for safety, yet there have been good safety reports on sizes as small as 21". Japanese certification for safety yields 21" as the minimum possible handlebar size that will not dramatically increase the number of bicycle injuries.

For back and wrist injuries, the North Road (think 3-speed) style is availble from 20 through 23 inches and this puts the weight onto your rear instead of your wrist, neck, back, knees, ribs, etc. . .

Anyway, you don't and shouldn't have to use drop bars (road bike) to go fast.

Fastest areodynamics are with your back straight. If you are hunched, then your handlebars are. . .too low. This is because your frame is too short. However, it is okay to use a smaller frame as long as you make up the difference with your seat and handlebar height. Most people only pump up the seat height. . . and then they have this "falling over" feeling.

For instance, a proper size frame has only 1 inch between the top bar and your crotch. You won't ever see this in a mountain bike because the proper size bike will strike your "goodies" with that top bar.

Do the math. However much shorter your current bike is than the proper size. . .add that much more height to your handlebars. Now your mountain bike will fit properly.

A proper height and width of the handlebars increase body leverage making you much more comfortable AND much faster.

You can use road bike body mechanics and road bike tires to get road bike speeds without purchasing a road bike.

There's absolutely no reason (except running out of gears on the high end) that a $35 mountain bike can't keep a minimum 21 mile per hour pace (as usual for road tours) with a $3500 road bike. There should be absolutely no greater effort required for the mountain bike except when the heavier bike goes up a hill.

There's also no reason to compromise your safety and comfort in exchange for speed. There are plenty of fast bikes that 1) are not made of carbon fiber, 2) are not unsafe, and 3) are not uncomortable


I like this thread about speeding up mountain bikes, but let's keep the safety and comfort AND add a lot of speed. There's a very big reason that most of us didn't buy a road bike.

So, make a bike that is greater than both.
Keep those tires at least 1.3" wide. Adjust your new-style compact frame's seat AND handlebars to the proper fit.

One last thought. . .53 tooth front chainring to keep up with the road bikes. To totally embarrass the road bikes, Schlumpf twin speed bottom bracket $$$ at Harris Cyclery for a 165% or 200% speed boost.

Cruising with (or in front of) the road bike pack at speeds above 20 miles per hour does not require any more force than herding a mountain bike up a short grassy hill. So if your legs are strong enough to be zipping up and down grassy hills and mountain bike trails for 3 hours, then you're plenty ready for the road.

Except, for quite a few odd expressions on the faces of $3500 road bike owners. . .as you pass.

 

[artemidorus]

danielhaden, interesting posts - I could have used you as a reference during a "debate" on this board some months ago.
Comment on this, however: most authorities quote energy losses through deformation of larger tyres which relates to the bulk and consistency of the rubber and the thread count. This is said to be the main reason for the fact that 23mm tyres are faster than fatter tyres on good surfaces when appropriately inflated for the rider's weight. Anecdotally, my MTB commuter (fixed fork, slick 1.5" tyres inflated in proportion to my weight as per some web site I found once but can't cite , 70psi front and 90psi rear, I'm 90kg) is much slower than my road bike over my daily ride. My bars and seat are about the same height on both bikes. What do I need to fix so I can throw my TCR away?

 

[danielhaden]

It is much slower than your road bike? Well, that's odd. Physically speaking, the machines are very similar.

First, your riding position may be a bit off on the MTB because it is necessarily a smaller frame. Try adjusting your seat for "crease support" whereby the edges of the seat would contact the seams of "brief" underwear. You'll need to sit well far back on the seat. You'll need to have the seat far back on its rails (as far as it will go). You'll need to have the seat now high enough that if you really mash the pedals that you lift up off the seat by about 2mm. You can't see this clearance, but you can feel it. Normal pace riding should result with full leg extension while you're on the seat. Correct any misfit by adjusting or replacing the handlebars. Small frames (all MTB) have small headtubes. This usually makes the handlebars a whopping 4 inches too short. Be prepared for a small frame to have a ridiculously long stem or handlebars that look like an albatross to make up for the size difference.
Not riding down "falling down" over the front of the bike can make a huge speed difference by making the front tire perform less work.



After adjustment, ride it and grip over the brake mounts so that your body is in the same position as the road bike. I wouldn't recommend riding this way unless there's a lot of wind. See if you gain about 4 miles per hour.

There's one sure thing to cause slowness:
Riding in the 11 or 12 rear sprocket because the largest front chainring has only 44 teeth, and in this case, you'll need a 52 tooth large chainring or higher.

This 44x12 combo is going to "bind" your chain just a bit and create a rather awful slow sensation. You need a big enough chainring (front) that you can ride in the 14 tooth and larger rear sprockets at the speed you wish to go.

In fact, the 14 tooth rear sprocket can also bind your chain, but you can usually adjust the derailer clearance to smooth it out. Smaller sprockets are for downhill riding.

You can try adjusting your wheel forwards or backwards. . .probably as far forwards as you can get and still have the wheel on straight.

To make it worse, most MTB derailers don't have the "B" screw (Shimano) or the "A" screw (Campy). So, the only way to adjust the clearance angle is to move the wheel about. There is no correct angle for the rear derailer, but you may have it "favor" the high gears or "favor" the low gears. This adjustment is usually good for about 7 miles per hour gain if you "favor" the high (tiny rear sprocket) gears by giving it enough clearance that it won't bind the chain.

Oil your chain with lightweight car motor oil. Shift into your highest gear and oil the chain where it bends across the smallest rear sprocket. This will put the oil INTO the chain. Anywhere else will simply put the oil on top of the chain where it will immediately come off onto your pants. Have your bike tipped towards you so that you don't oil the tire.

Middleweight tires are from 1.5 through 1.8 sizes:
These are known to have problems pacing a high speed. They are for only one purpose and that is gravel roads (slow loaded touring). They aren't large enough to "float" over road bumps, so there is no speed advantage from smooth rolling. They aren't small enough to rise the majority of their tread above the surface like a road bike tire, thus gaining an advantage through small contact. In fact, there is no advantage to middleweight tires. Middleweight slick tires are even worse than knobbies because 100% of the soft, gummy rubber is making contact with the road.

So, I would state that if your chain isn't binding over the rear sprocket and if your front chainring has more than 50 teeth, then the cause of slowness is the tire.

Most troublesome is the front tire. Middleweight and larger tires need far less air in the front tire if you have an upright riding position. You can get tire speed from flexability (touring application: you will be struck by a bump, so make it a soft bump) or from minimal contact patch (Road application: you will be struck by a bump, so make it a small bump).
It is also completely acceptable to run unmatched tires. This can be tire size or inflation.

Try 40 pounds of air in that front tire, and certainly no more than 50 unless you have drop handlebars.
If the tire gets even slower, replace it with something that is not so sticky (gummy, "slick" rubber=slow).


Try a 1.0 (if you have small rims) or 1.25 - 1.3 (MTB rims) racing tire (tread has almost no effect) on the back wheel. Since it isn't responsible for steering, there's no safety problem with a small back tire.


It is certainly not the wheel size that affects bike speed. Recumbents fly past on little 24" wheels.

I'm currently testing out the Tom Ritchey 1.4 to see if it can do both touring and road well or if it does neither job well just like the 1.5 through 1.8 sizes.

I've been experimenting with tire sizes for a while now.
1.9 and higher sizes with relatively smooth tread (smooth to the touch with visable tread) are like riding velvet tires over glass. These are Schwinn Typhoon and Schwable Big Apple beach cruiser tires. While a tiny bit more effort to pace in the 20 MPH range, the very hard (hard rubber, not sticky!) tread, 3/4" contact point and flexability makes for a fast ride with zero bumps. Offroad is equally pleasant. The problem? These (with 40 front, 60 rear) make the bike impossible to sit on at the stoplight.

Above all avoid non knobby "running stripe" tires. While a bald or slightly smoother center makes knobbies fly (because they're still flexable), the technology does not work for high inflation road tires. Without tread, the tire cannot compress over the minute road bumps and the result is like riding with the brakes on. A new technology, "reversed tread" supposedly addresses this issue, but I haven't purchased any to test them.

Yeah, there's a lot of guesswork on the tires, and I haven't found out why the middle ranges don't work well. But, those are made for loaded touring and they do not pace well.

 

[danielhaden]

If you want to convert a mountain bike into a road bike, you'll need some equipment that does exactly the same thing: Trade safety for speed.
Road bikes are 400% more likely to crash with male riders, although there is no safety difference for female riders.

Here's how:
Mavic XM317 rims
Continental Grand Prix 26x1

Now, you no longer own a mountain bike and you're much more likely to crash.

 

[gclark8]

After looking at some of your stats, I measured the flat bars on both my bikes, 560mm & 580mm. I wonder, statisticly speaking, what the increased risk would be if I fitted 400mm time trial bars to one of the bikes, considering TT bars are similar to flat bars with bar ends. (not aero bars)

 

[danielhaden]

Time trial bars? Well, unless you're very tiny (small size shirts are too large) then it's going to be hard to breathe, difficult to ride a distance, and possibly cause a deformation of some sort that requires extensive physical therapy. Those are built exclusively for time trials, and they don't do multiple jobs.

Certainly time trial bars could be used if the stem had a long projection. This would slow down the action of the steering to compensate for the speedier (dodgy) action of the time trial bars. They will still damage your body unless your shoulders are about the same width as the handlebars.

534mm (21") is about the minimum for safety, unless you get a stem with more forwards reach.

Some road bikes push this down to 483mm, but those use a longer projection from the stem that causes you to reach out farther. This is popular on the marketing-hype-inspired compact frames. This won't work on a normal size frame because you'll go over the handlebars at the first bump.


Flat bars of all types will damage wrists.
Flat bars combined with small frames (most MTB) causes OTH, over the handlebar crash. Handlebars with a rise or a very long stem can prevent these crashes.

Handlebars that are narrower than your shoulders or lower than your waist will cause back and neck pain.


So, if you're planning on spending more than 20 minutes on the bicycle, consider some 21" (if your shirt size is small or medium) to 23" (if your shirt size is large) handlebars that reach back toward you.

They don't have to be classic style touring/North Road style to do the job. That's comfortable and tree-proof, but not required.

You can use VERY sporty adult BMX sport bars. These look great on a mountain bike. Various rises are available to prevent OTH (over the handlebars) and some even have a very cool-looking crossbar. It is also very important is that the reach (curve) match the angle of your wrists. Because these have all of the curve within the center section, it is easy to cut these off at the right width, and your brakes, shifters, etc. . . will all still fit.


Reaching out farther and narrower will help you hide from the wind at a fast pace. However, it is useless to go significantly narrower than your shoulders. Reaching DOWN is a fairly horrible idea, but reaching out will not damage the body. There are stems with longer reaches and there are some funny looking adapters for use with an overly-small bike frame. With the small frames on most MTB, it works even better as a first step to start with getting the seat as far back as possible--even if you have to use a duplicate set of clamps or a specially bent seat post. As a second step, you'll need handlebars at least as high as your waist (prevents body damage) that reach back towards you with enough angle to provide a natural angle to your wrists. The last step to stop wind resistance is to continue to stretch the bike with a stem that reaches out forwards.

How do you know if you have a small bike frame that could benefit from stretching the dimensions? If your "goodies" don't hit the top bar, the bike has a small frame. Stretching the stem up and out (forwards), handlebars up, and seat out (backwards) will make up the size difference.

 

[danielhaden]

Now I'm on a quest to find middleweight tires that work.

Middleweight= 1.5 - 1.8 wide

Why? 26x1, 26x1.25, 26x1.3 can blow off mountain rims because they're smaller than the wheels.



Middleweights:

WTB slickasauras 26x1.5 Speed AND tread!! KUDOS!!

Tom Ritchey 26x1.4 Speed, but no traction.
-blows off of mountain rims above 70 PSI.

GEAX StreetRunner 26x1.6 = VERY slow
-big tires shouldn't try to use sticky, gummy, rubber for extra traction. This works great for tiny tires, but it isn't necessary at this size, and it is like cycling on sand instead of pavement.
-performs exactly like the majority of slow 1.5" city tires, but the GEAX has less tread.



Current middleweight record-holder:

WTB Slickasauras!! No blow-off's, fastest 1.5" wide tire, fast cornering, lots of traction, works in the rain, and it is fast!

 

[scotty72]

Just stuck Conti Sport Contacts 1.6 on my MTB

very good

Scotty

Now I'm on a quest to find middleweight tires that work.

Middleweight= 1.5 - 1.8 wide

Why? 26x1, 26x1.25, 26x1.3 can blow off mountain rims because they're smaller than the wheels.



Middleweights:

WTB slickasauras 26x1.5 Speed AND tread!! KUDOS!!

Tom Ritchey 26x1.4 Speed, but no traction.
-blows off of mountain rims above 70 PSI.

GEAX StreetRunner 26x1.6 = VERY slow
-big tires shouldn't try to use sticky, gummy, rubber for extra traction. This works great for tiny tires, but it isn't necessary at this size, and it is like cycling on sand instead of pavement.
-performs exactly like the majority of slow 1.5" city tires, but the GEAX has less tread.



Current middleweight record-holder:

WTB Slickasauras!! No blow-off's, fastest 1.5" wide tire, fast cornering, lots of traction, works in the rain, and it is fast!

 

[artemidorus]

danielhaden, I would be interested in seeing your sources for the safety data concerning tyre size, bar width, bike type and gender. I am also interested in your sources for the rolling resistance information. Can you give a reference or a URL?

 

[gclark8]

I'll second that. I would like to see all his sources. A lot of his comments don't confirm some of my recent experiences.

 

[robalert]

Now I'm on a quest to find middleweight tires that work.

Middleweight= 1.5 - 1.8 wide

Why? 26x1, 26x1.25, 26x1.3 can blow off mountain rims because they're smaller than the wheels.



Middleweights:

WTB slickasauras 26x1.5 Speed AND tread!! KUDOS!!

Tom Ritchey 26x1.4 Speed, but no traction.
-blows off of mountain rims above 70 PSI.

GEAX StreetRunner 26x1.6 = VERY slow
-big tires shouldn't try to use sticky, gummy, rubber for extra traction. This works great for tiny tires, but it isn't necessary at this size, and it is like cycling on sand instead of pavement.
-performs exactly like the majority of slow 1.5" city tires, but the GEAX has less tread.



Current middleweight record-holder:

WTB Slickasauras!! No blow-off's, fastest 1.5" wide tire, fast cornering, lots of traction, works in the rain, and it is fast!

wouldn't that depend on your rims? i've had no probs with my 1.3 contact sports on my rims that can fit 26x2.5 hookworms

fast 1.5s... i'd choose the maxxis xeniths

 

[gclark8]

Move over Conti, Michie has arrived:

Today I received a new Michelin Catalogue, Hard Cover, In the MTB section two new 26" slick tyres.

"XCR Road" 26x1.4 66TPI All Black
"XC Road" 26x1.4 33TPI All black

"Road training tire for urban use
Very lightweight

Its light weight, supple casing and slick tread transform your mountain bike into a road bike. A soft rubber mix helps provide cornering grip and responsive braking."

A link: http://two-wheels.michelin.com/2w/f...2005183349&lang=EN&codeRubrique=2092004115810

These may give Conti Sport Contact a run for the money!

 

[rek]

I used the Continental SportContact 26x1.3" tyres on my MTB-commuter before I parted the bike out. They were an excellent tyre, but I found them really hard to get on and off the rim -- the only tyres I've ever had to break out the metal tyre-levers for! I'm assuming the wider versions would be easier to mount (either that or I just got a weird pair)

My current commuter has 700c wheels and am currently using some Maxxis Overdrive 700x37c tyres designed primarily for hybrids it seems. Can't complain about 'em, got them cheaply on eBay. They do the job of a "go-anywhere" type tyre well, and have a puncture layer belt built-in. Seems to work just dandy over road and gravel/broken trails.

They're a bit wide if anything though, my next commuter tyres will probably be something more in the 28-32 width range. They're probably needlessly heavy too, but hey, commuter bikes tend to have heavy bags and such anyway ...