Mountain Bike Reviews Forum banner
1 - 11 of 11 Posts

·
No Reputation!
Joined
·
1,727 Posts
Discussion Starter · #1 ·
Ok, thanks to all you guys who weighed your rear wheels for me, I checked my rear wheel and it's a mighty 2.3kg in the "ready to ride state" (tires, qr, rotor)

It's an xt hub, 14/15 spokes, not sure of nipples, velux stips, a tube of some type, and IRC Mythos front tire (on the rear wheel).

The way I see it, I could build something light and reliable (xtr/king/etc w/stans) with 'regular' spokes and alu nips and save maybe 1.5#. Does this sound right? And the bigger question...will this help me beat my buddies when we race? 1# isn't very much when you are already at 206 1/2# bike + rider.
 

·
Recovering couch patato
Joined
·
14,017 Posts
If the 29" thing alone doesn't beat your buddies, perhaps 32" will?
I don't like to admit it, but 5lb off ME works better than 10lb of the bike...

There's a bit more to shave "off" the IRC tire, put a Jones on there as well, or a fibreglass WTB (if you can find one).
 

·
Registered
Joined
·
215 Posts
rotating mass

Forgot were I read the study (roadie thing) but I read a study about speed related to weight loss of various bike parts. Some of it doesn't relate to MTB cause we don't draft etc.

If you can lose weight anywere on a bike to gain the most effect it will be in rotating mass, ie wheels, cranks, pedals.

The study I saw showed the difference on a 2 mile climb of what the time difference would be losing 1lbs of your bike (frame etc) vrs 1 lbs off the wheels. For every lb off your wheels you'd need to lose appr 10lb off other parts to get the same time savings.
This was on a hill and I don't remember grade etc. If you're a geek go to www.analyticalcycling.com and you can play with the #'s yourself.

If I can find the study again, I'll post the link.

On the flats, not as much of a difference but you will see improved acceleration with lighter wheels. So if your course/trails are winding, slow down speed up and hilly, lighter wheels will help. If it's relatively flat and you maintain speed, lighter won't make as much of a difference.

With climbing bikes in pro road cycling (minumum weight limit) the trend is towards heavier frames so they can run lighter wheels, cranks, pedals and not go over the limit. Rotating mass is extremely critical in the pro peleton on climbing stages but the same guys often use heavy aero wheels on the flats.

So if you want to feel faster and climb faster, get lighter wheels. It's a noticeable difference. It may not make you faster than your frinds (it's really the engine that counts) but you'll feel faster.

At 206 though you can't skimp to much or reliablity will become a serious issue. A stan's rim (400g), LIGHT 29er tube (130g) and Bontager tire (575g) will save 100-300grams depending on your current rim.

Want to save more, Get a king, am classic etc hubset. Don't think you could get away with 14/17 spokes though they would save another 80g per wheel. Maybe 36 hole wheels.

Enough ranting, good luck.
 

·
Recovering couch patato
Joined
·
14,017 Posts
On a constant climb, you might as well get a fullface helmet to add 2lb, odd put 2lb extra in the tires, same difference in speed. Rotating mass starts working in corners and when accelerating (changing speed, climbing is all too often mixed up with accelrating). A 20lb bike that's all wheels and weightless frame and parts, is just as fast on Alpe d'Heuz as the All-frame-no-wheels bike. Speed on such climbs is about as constant as the moon circeling earth, no accelleration to mantion.

Rockdogger said:
Forgot were I read the study (roadie thing) but I read a study about speed related to weight loss of various bike parts. Some of it doesn't relate to MTB cause we don't draft etc.

If you can lose weight anywere on a bike to gain the most effect it will be in rotating mass, ie wheels, cranks, pedals.

The study I saw showed the difference on a 2 mile climb of what the time difference would be losing 1lbs of your bike (frame etc) vrs 1 lbs off the wheels. For every lb off your wheels you'd need to lose appr 10lb off other parts to get the same time savings.
This was on a hill and I don't remember grade etc. If you're a geek go to www.analyticalcycling.com and you can play with the #'s yourself.

If I can find the study again, I'll post the link.

On the flats, not as much of a difference but you will see improved acceleration with lighter wheels. So if your course/trails are winding, slow down speed up and hilly, lighter wheels will help. If it's relatively flat and you maintain speed, lighter won't make as much of a difference.

With climbing bikes in pro road cycling (minumum weight limit) the trend is towards heavier frames so they can run lighter wheels, cranks, pedals and not go over the limit. Rotating mass is extremely critical in the pro peleton on climbing stages but the same guys often use heavy aero wheels on the flats.

So if you want to feel faster and climb faster, get lighter wheels. It's a noticeable difference. It may not make you faster than your frinds (it's really the engine that counts) but you'll feel faster.

At 206 though you can't skimp to much or reliablity will become a serious issue. A stan's rim (400g), LIGHT 29er tube (130g) and Bontager tire (575g) will save 100-300grams depending on your current rim.

Want to save more, Get a king, am classic etc hubset. Don't think you could get away with 14/17 spokes though they would save another 80g per wheel. Maybe 36 hole wheels.

Enough ranting, good luck.
 

·
Registered
Joined
·
215 Posts
wheel mass

Not trying to start an argument cause I ain't no engineer but this topic has been beat to death on the RBR board.

"A 20lb bike that's all wheels and weightless frame and parts, is just as fast on Alpe d'Heuz as the All-frame-no-wheels bike. Speed on such climbs is about as constant as the moon circeling earth, no accelleration to mantion."

Obviously total weight makes a difference but If wheel weight made no difference on a long steady climb, why do all the roadie pro's use light weight wheels in the mountains? They can't make their bikes any lighter than I think 6.8kg. They all weigh the same but they try to stay in those guidlines and use lighter wheels.

recent velonews article:
http://www.velonews.com/tech/report/articles/6729.0.html

Obviously they feel it makes a difference. LA & US postal spend mucho $ studying this stuff to get every extra advantage and went to the point of having bontrager design 200g carbon rims for this years TDF mountain stages.

I'll have to find that study for you, you would find it very interesting (as I did).cause the whole point of the test was total weight (rider & bike) on a climb vrs same overall weight but lighter wheels and the lighter wheels won big time.
Something to do with wattage needed to spin the wheels etc.

Prior to this study and some research I was under the same assumption as you.

I'll find the study, you'll be as amazed as I was.
 

·
A hopped on pop.
Joined
·
1,397 Posts
i have king classics laced to delgados...

my 29er wheels;
king classic hubs
salsa delgado rims
wheelsmith db 14/15 spokes and alloy nipples
built 32 hole, 3 cross, by me...
front wheel is 868
rear is 1016
no rim tape (but i use 3m strapping tape).

cheers and i hope this helps.

Fastskiguy said:
Ok, thanks to all you guys who weighed your rear wheels for me, I checked my rear wheel and it's a mighty 2.3kg in the "ready to ride state" (tires, qr, rotor)

It's an xt hub, 14/15 spokes, not sure of nipples, velux stips, a tube of some type, and IRC Mythos front tire (on the rear wheel).

The way I see it, I could build something light and reliable (xtr/king/etc w/stans) with 'regular' spokes and alu nips and save maybe 1.5#. Does this sound right? And the bigger question...will this help me beat my buddies when we race? 1# isn't very much when you are already at 206 1/2# bike + rider.
 

·
No Reputation!
Joined
·
1,727 Posts
Discussion Starter · #9 ·
I'm confused about this study

http://www.active.com/story.cfm?story_id=7815

He says

A few years ago I completed a study with Ned Frederick of Exerter Research that showed how the addition of 250 grams to a shoe/pedal system or 500 grams total for both right and left feet (about the difference between the lightest and heaviest shoe/pedal systems on the market) would require an additional power output of 1.3 percent on rotational power requirements at constant speeds on a level road.

then says

The effect on climbing, and accelerating, would be about 0.4 percent, but only during periods of climbing and accelerating. The effect on rolling resistance would be about 0.07 percent. This means that the net effect due to all factors of a realistic increase of 250 grams in mass on each leg would be to increase the power required by a cyclist by approximately 1.5 to 1.7 percent

Which, if I'm reading this right, says that when you cut weight you get about three times more benefit on the FLATS vs the HILLS and during ACCELERATION. As in a greater benefit on the flats and a less great benefit on the hills. That just does not make sense to me.

I did like this one tho...

Steve Hed used one of the formulas we developed through F-One and learned that the clip-on's weight would cost Lance six or seven seconds during his assault up L'Alpe d'Huez.

So to me that means the lightest mini-aerobars you can make (maybe 200-300g??) will cost a guy only 6-7 seconds in a 3000ft, 40 minute climb? That's nothing! I lose that much when I burp or start thinking about the hottie ahead of me (or both!) This would suggest that an extra pound of static stuff is no big deal.

In conclusion, I think I could save some weight on my wheels but I'm thinking (tonight anyway) that it's just not worth it. But if you find that study...I might need to change my mind :) Thanks for posting the links too :)
 

·
No Reputation!
Joined
·
1,727 Posts
Discussion Starter · #11 ·
That's 1709g for the rear wheel

vs.my 2300g for the rear...now that is a big difference! My frame is disk only so I'd pick up some with the rotor and the hub....but wow... I had a paul hub on my 26" ss bike with the white industries freewheel-it always was no trouble. Now all of that blather I wrote last night about not worrying about the weight seems so.....wrong....

nightfire said:
1529g

Salsa's, CX-Ray, Paul Word, Conti Vapour and Conti Tubes.

Add another 180 if you want to inlude the freewheel. (White Ind)
 
1 - 11 of 11 Posts
Top