Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Mountain Biking Mountain biking is one of the fastest growing sports in the world. Check out this forum to discuss the latest tips, tricks, gear and equipment in the world of mountain biking.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 07-14-11, 11:00 AM   #1
Ridin
Newbie
Thread Starter
 
Join Date: Jul 2011
Location: CA
Bikes: Giant MTB
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
My 26" seems slow, any suggestions? Tires? 29er maybe?

I ride a Giant revel, mostly on the street and it just seems sooo slow! I'm also a slow rider btw. When I ride with others, it seems like I have to work allot harder to keep up. I haven't had any experience with 29ers but i'm wondering a 29er would make a huge difference in speed.
I can also try changing to street tires but I don't think I want to hassle with changing them back every time I want to hit the trails. I don't want to switch to a road bike cause I think I'll break it lol
How many of you have switched to 29ers for speed reasons?
Ridin is offline   Reply With Quote
Old 07-14-11, 11:42 AM   #2
Steev
Senior Member
 
Steev's Avatar
 
Join Date: Jul 2005
Location: Backwoods of Ontario
Bikes:
Posts: 2,150
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Slow? It's the motor.
Steev is offline   Reply With Quote
Old 07-14-11, 11:44 AM   #3
ShimmerFade
Senior Member
 
Join Date: Jun 2010
Location: Germany
Bikes:
Posts: 269
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Ride more! Also do some climbing it will up your speed and fitness in a hurry.
ShimmerFade is offline   Reply With Quote
Old 07-14-11, 11:48 AM   #4
Elevation
Senior Member
 
Join Date: Jul 2008
Bikes:
Posts: 135
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
engine check
Elevation is offline   Reply With Quote
Old 07-14-11, 12:08 PM   #5
slowandsteady
Faster but still slow
 
slowandsteady's Avatar
 
Join Date: Jun 2006
Location: Jersey
Bikes: Trek 830 circa 1993 and a Fuji WSD Finest 1.0 2006
Posts: 5,979
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
MTBs are slow on the road, especially with knobby tires. Slicks will increase your speed by about 2mph or so.
slowandsteady is offline   Reply With Quote
Old 07-14-11, 12:27 PM   #6
AdamDZ 
Bike addict, dreamer
 
AdamDZ's Avatar
 
Join Date: Nov 2009
Location: Queens, New York
Bikes:
Posts: 5,165
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Swap the fork for a rigid one and put on high pressure road tires. It'll make a lot of difference.
AdamDZ is offline   Reply With Quote
Old 07-14-11, 12:30 PM   #7
ed 
.
 
ed's Avatar
 
Join Date: Oct 2005
Location: The Summit of Lee
Bikes: Hecklah
Posts: 10,932
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
29er will be slower on the road than a comparable 26er. The larger hoops only help when there are bumps to level. The increased rotating weight will accelerate slower and work you harder.

Invest in a quality 26"wheelset and some light slicks. Go climbing and pump up your quads.
ed is offline   Reply With Quote
Old 07-14-11, 12:55 PM   #8
prathmann
Senior Member
 
Join Date: Nov 2008
Location: Bay Area, Calif.
Bikes:
Posts: 6,137
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 107 Post(s)
Quote:
Originally Posted by Ridin View Post
I can also try changing to street tires but I don't think I want to hassle with changing them back every time I want to hit the trails.
Lighter tires with minimal tread pattern will reduce rolling resistance and depending on your trails you may find that they work ok there too.
prathmann is offline   Reply With Quote
Old 07-14-11, 07:11 PM   #9
AdamDZ 
Bike addict, dreamer
 
AdamDZ's Avatar
 
Join Date: Nov 2009
Location: Queens, New York
Bikes:
Posts: 5,165
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I run Schwalbe Marathon Plus Tour 26x1.75 tires on my trekking/touring bike. It's a rigid 26" MTB with racks and stuff for touring that sees asphalt about 75% of the time. These tires give you a good balance of smooth rolling on asphalt and some off-road capability. There is my lone review of these tires on Universal Cycles. But if you don't care for off-road then there are even better 26 road tires like the Schwalbe Durano 26x1.10. There are even slicks for 26 wheels. I would have gone with something thinner and slicker (?) but my treks sometimes take me on moderate forest trails or country dirt roads so I want some off road capability.

Let me tell you from experience: I had a 700 touring bike with 700x32 tires, didn't care much for road geometry so I sold it and the current 26" MTB touring bike with the above tires works just as well on long road trips, with the added benefit of slightly lower gearing for long climbs with 60lbs of gear due to smaller wheel size. On both bikes my daily average speed while touring is the same. So bigger wheels didn't make any difference for me.
AdamDZ is offline   Reply With Quote
Old 07-15-11, 08:16 AM   #10
FrenchFit 
The Left Coast, USA
 
FrenchFit's Avatar
 
Join Date: Feb 2008
Bikes:
Posts: 3,053
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 34 Post(s)
Hey, me too! Similar rig, a 7000zx with Marathon Supremes set up for touring. It cruises at 15mph, respectable given all the junk on the bike.

As to "29er will be slower on the road", I think the experience is they are often faster. With fast rolling tires, the increased rotating weight smooths out the road and provides more momentum at speed. Over the long haul I tend to agree the wattage the 29er requires to stay at speed is greater, but around the town experience is the 29ers are significantly faster...the feeling at speed is they want to be pushed over the top of the gear. At the same speed 26ers feel topped out. My sense is those who ride 29ers regularly end up riding faster, science or no. I think every 29er rider loves to talk about how they chase down roadies.
FrenchFit is offline   Reply With Quote
Old 07-15-11, 08:24 AM   #11
Mithrandir
Senior Member
 
Mithrandir's Avatar
 
Join Date: Jun 2011
Location: Buffalo, NY
Bikes: 2012 Surly LHT, 1995 GT Outpost Trail
Posts: 2,400
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by ed View Post
29er will be slower on the road than a comparable 26er. The larger hoops only help when there are bumps to level. The increased rotating weight will accelerate slower and work you harder.

Invest in a quality 26"wheelset and some light slicks. Go climbing and pump up your quads.
Related question.

My MTB is 16 years old now. There's quite a few gaps in its usage however; used it lightly from 1995-1998, used it heavily from 2004-2005, and am currently using it very heavily starting in 2011. It was stored indoors from 2004-2011, and in a covered outdoor shed from 1995-2003.

Do you think I would benefit from a new wheelset? I've read about some people saying that wheel bearings tend to go bad and have to be replaced, but I can't really find any information about how long this process takes.

I've been considering getting a new rear wheel anyhow, as I'd love to upgrade from 7 speed to 9.
Mithrandir is offline   Reply With Quote
Old 07-15-11, 08:33 AM   #12
ed 
.
 
ed's Avatar
 
Join Date: Oct 2005
Location: The Summit of Lee
Bikes: Hecklah
Posts: 10,932
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by FrenchFit View Post
Hey, me too! Similar rig, a 7000zx with Marathon Supremes set up for touring. It cruises at 15mph, respectable given all the junk on the bike.

As to "29er will be slower on the road", I think the experience is they are often faster. With fast rolling tires, the increased rotating weight smooths out the road and provides more momentum at speed. Over the long haul I tend to agree the wattage the 29er requires to stay at speed is greater, but around the town experience is the 29ers are significantly faster...the feeling at speed is they want to be pushed over the top of the gear. At the same speed 26ers feel topped out. My sense is those who ride 29ers regularly end up riding faster, science or no. I think every 29er rider loves to talk about how they chase down roadies.
Why would you need to smooth out the road?

29'er riders like to brag about chasing down roadies b/c they make themselves work harder to do it b/c they don't want to admit that they shelled out 3k for a gimmick only to pimp it on the MUP.
ed is offline   Reply With Quote
Old 07-15-11, 12:20 PM   #13
scyclops
dont make me get the belt
 
scyclops's Avatar
 
Join Date: May 2010
Location: Southeastern U.S.
Bikes:
Posts: 510
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I think there's an important distinction to be made between wheel diameter and wheel weight (rotational mass) I don't have a link handy but I've seen the calculations done by various people who seem to know what they're talking about, and with all other factors being equal - including weight - the difference in energy required to spin up the 29" vs 26" (based solely on diameter) is so miniscule as to be insignificant. Evidently this is due to the fact that the smaller wheel has to turn more RPMs to cover the same distance as the larger wheel - thereby virtually canceling out any effective gearing disadvantage of the larger wheel.
As to rotational mass/weight, a heavier 26" wheel takes more energy to accelerate than a lighter one - and that's obviously got nothing to do with diameter. Also, rotational weight cuts both ways with respect to momentum. Heavier takes more energy to get rolling, but once up to speed is harder to stop / slow down. This is the very definition of inertia.
So if you were to compare a 26" wheel to a 29" wheel of the same weight, I'd have to say advantage 29er.

Ok, before I get jumped all over, I'm not even pretending to know mathematical physics, I'm just relating stuff that seems to be undisputed by any people that do know about such things. And BTW, I have no plans to go 29" any time soon.

Carry on.

Last edited by scyclops; 07-15-11 at 12:31 PM.
scyclops is offline   Reply With Quote
Old 07-15-11, 12:38 PM   #14
AdamDZ 
Bike addict, dreamer
 
AdamDZ's Avatar
 
Join Date: Nov 2009
Location: Queens, New York
Bikes:
Posts: 5,165
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by ed View Post
Why would you need to smooth out the road?

29'er riders like to brag about chasing down roadies b/c they make themselves work harder to do it b/c they don't want to admit that they shelled out 3k for a gimmick only to pimp it on the MUP.
Pimp? Because of a few threads here I had a look at 29rs. Damn, they look comical to me

And I dropped roadies on uphills on my loaded bike. Well, they might have been at their 99th mile while I was at my 9th or so, but still, it felt good
AdamDZ is offline   Reply With Quote
Old 07-15-11, 02:39 PM   #15
corvuscorvax
Gone.
 
Join Date: May 2011
Bikes:
Posts: 509
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by scyclops View Post
I've seen the calculations done by various people who seem to know what they're talking about, and with all other factors being equal - including weight - the difference in energy required to spin up the 29" vs 26" (based solely on diameter) is so miniscule as to be insignificant. Evidently this is due to the fact that the smaller wheel has to turn more RPMs to cover the same distance as the larger wheel - thereby virtually canceling out any effective gearing disadvantage of the larger wheel.
[...]
Ok, before I get jumped all over, I'm not even pretending to know mathematical physics, I'm just relating stuff that seems to be undisputed by any people that do know about such things. And BTW, I have no plans to go 29" any time soon.
You're right, and the physics is not very complicated. Take a bike with total mass M, and two wheels, each with mass m and radius r. The kinetic energy (translational + rotational) of the bike moving at velocity v is

E = (1/2) M v^2 + 2 * (1/2) I w^2,

where "^" indicates exponentiation, I is the rotational moment of inertia of each wheel (approximated as infinitely thin hoops with radius r)

I = m r^2,

and w is the angular velocity of the wheels when the bike is moving with velocity v,

w = v / r.

Plugging the above two expressions into the kinetic energy gives

E = (1/2) M v^2 + m r^2 (v/r)^2
= (1/2) (M + 2 m) v^2

Note that the radius of the wheel cancels out: the kinetic energy of the bike at any given speed is completely independent of the wheel diameter, as long as the larger/smaller wheels have the same mass. However (this is interesting in general) note that adding a gram to the rim has twice as much effect (adds to both "m" and "M") as adding a gram to the frame (adds to just "M").

But, you say, "real wheels aren't infinitely thin hoops!" Correct. But it makes no difference to the conclusion that wheel size is irrelevant. For any cylindrically symmetric wheel, the moment of inertia will in general be of the form

I = K m r^2,

where K is a constant (always < 1) that depends on the mass distribution in the wheel. Then the radius still cancels out of the energy,

E (1/2) (M + 2 K m) v^2.

http://xkcd.com/54/

Last edited by corvuscorvax; 07-15-11 at 03:15 PM.
corvuscorvax is offline   Reply With Quote
Old 07-15-11, 02:44 PM   #16
Ridin
Newbie
Thread Starter
 
Join Date: Jul 2011
Location: CA
Bikes: Giant MTB
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks for the tips!
Yes, the motor definitely needs a major tune-up, working on it!
Tires will make a difference and even though I ride mostly paved, I don't want to swap tires every time I hit the trails.
It seems to me that larger wheels would roll faster once up to speed, most road & hybrid bikes have them right?
I'll probably eventually get a hybrid for the paved stuff.
Ridin is offline   Reply With Quote
Old 07-15-11, 02:51 PM   #17
Daspydyr 
Pedals, Paddles and Poles
 
Daspydyr's Avatar
 
Join Date: Oct 2009
Location: Btw the Mohave desert and AREA 51
Bikes: Santa Cruz Tallboy, Ridley Noah, Scott Spark 20
Posts: 5,353
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Its the Indian not the Arrow, or the motor vs the bike as previously stated.

Try doing some "Intervals" and "Stomps" for a couple weeks. It is surprising how it builds you up. Intervals is riding as fast as you can for 60 seconds in a comfortable gear and then rest for 90 seconds, repeat 5 times. The third week switch the numbers, pound for 90 seconds and rest 60. After a month tru doing 2 sets of 5.

STOMPS help speed and climbing. On a flat stretch of road get riding in a comfortable gear, then drop gears so that you are rotating maybe 50 rpm. Get out of the saddle and stomp your pedals hard until you get back up to 80 rpm and maintain for 60 seconds. 5 sets.

If this don't work take 2 aspirin and repost.

How come all the speedy free riders in the posted videos seem to be riding 26ers? Just curious.
__________________
I think its disgusting and terrible how people treat Lance Armstrong, especially after winning 7 Tour de France Titles while on drugs!

I can't even find my bike when I'm on drugs. -Willie N.
Daspydyr is offline   Reply With Quote
Old 07-15-11, 02:51 PM   #18
BlueRaleigh
Senior Member
 
Join Date: Mar 2011
Bikes:
Posts: 317
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I use to ride a mountain bike on the road many years ago, before I got my first road bike. Now it's utterly painful (mentally) to ride a mountain bike on pavement. Once you get use to how fast a road bike rolls on pavement, you'll never want to ride a mountain bike on pavement again.

I say pick up a road/touring bike (or even a fixed gear!) and keep the mountain bike in the dirt.
BlueRaleigh is offline   Reply With Quote
Old 07-15-11, 02:57 PM   #19
ShimmerFade
Senior Member
 
Join Date: Jun 2010
Location: Germany
Bikes:
Posts: 269
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I think the point people are making is that a 29er will probably not make you noticeably faster. If you are really concerned with speed on pavement then you need a bike designed for the road. If you want to keep only your MTB, and make it faster, investing in slicks is the way to go. If you don't want to swap tires all the time you could invest in a new wheel set which you could then quickly swap out before riding depending on the conditions of where you are riding.
ShimmerFade is offline   Reply With Quote
Old 07-15-11, 02:57 PM   #20
Daspydyr 
Pedals, Paddles and Poles
 
Daspydyr's Avatar
 
Join Date: Oct 2009
Location: Btw the Mohave desert and AREA 51
Bikes: Santa Cruz Tallboy, Ridley Noah, Scott Spark 20
Posts: 5,353
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 19 Post(s)
Quote:
Originally Posted by corvuscorvax View Post
You're right, and the physics is not very complicated. Take a bike with total mass M, and two wheels, each with mass m and radius r. The kinetic energy (translational + rotational) of the bike moving at velocity v is

e kinetic energy of the bike at any given speed is completely independent of the wheel diameter, as long as the larger/smaller wheels have the same mass. However (this is interesting in general) note that adding a gram to the rim has twice as much effect (adds to both "m" and "M") as adding a gram to the frame (adds to just "M").



http://xkcd.com/54/
SO, since a larger rim with longer spokes and perhaps a bigger hub will weigh more and cause more spin resistance?.!?...
__________________
I think its disgusting and terrible how people treat Lance Armstrong, especially after winning 7 Tour de France Titles while on drugs!

I can't even find my bike when I'm on drugs. -Willie N.
Daspydyr is offline   Reply With Quote
Old 07-15-11, 02:58 PM   #21
corvuscorvax
Gone.
 
Join Date: May 2011
Bikes:
Posts: 509
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Daspydyr View Post
SO, since a larger rim with longer spokes and perhaps a bigger hub will weigh more and cause more spin resistance?.!?...
[Edit: whoops, think I misunderstood.]

Yeah, a heavier wheel will cause more spin resistance. It's the weight, not the wheel size per se.

Last edited by corvuscorvax; 07-15-11 at 03:07 PM.
corvuscorvax is offline   Reply With Quote
Old 07-15-11, 09:26 PM   #22
scyclops
dont make me get the belt
 
scyclops's Avatar
 
Join Date: May 2010
Location: Southeastern U.S.
Bikes:
Posts: 510
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Daspydyr View Post
SO, since a larger rim with longer spokes and perhaps a bigger hub will weigh more and cause more spin resistance?.!?...
The heavier wheel will be more resistant to any change in momentum - again, harder to get rolling, but once rolling, harder to slow down.
This is because - that's right, you guessed it - inertia is proportional to mass.

Last edited by scyclops; 07-15-11 at 09:49 PM.
scyclops is offline   Reply With Quote
Old 07-16-11, 06:10 AM   #23
BlueRaleigh
Senior Member
 
Join Date: Mar 2011
Bikes:
Posts: 317
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Remember that movie, Explorers, where they had that bubble that canceled out all inertia while inside it. That was cool.
BlueRaleigh is offline   Reply With Quote
Old 07-16-11, 06:53 AM   #24
ed 
.
 
ed's Avatar
 
Join Date: Oct 2005
Location: The Summit of Lee
Bikes: Hecklah
Posts: 10,932
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I think my reasoning for my statement is that...all things equal, 29'er will have more rotational weight. Of course if they weigh the same, things will be different, but theres no way you can build a 29er wheelset to be the same weight as the comparable 26.
ed is offline   Reply With Quote
Old 07-16-11, 07:24 AM   #25
scyclops
dont make me get the belt
 
scyclops's Avatar
 
Join Date: May 2010
Location: Southeastern U.S.
Bikes:
Posts: 510
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
ed, no disagreement with anything you said, just wanted other readers to be clear that it is the weight, and not the diameter, that is the critical variable (at least for the purposes of this discussion).

Last edited by scyclops; 07-16-11 at 07:36 AM.
scyclops is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 10:32 PM.