A month ago I laced up a set of MTB wheels using 36h Mavic X-618 rims. The build went smoothly (I'd laced up about a dozen wheels before this), and the wheels were tensioned and trued with no complications. But when holding the spinning front wheel (sans tire, tube and rim tape) by the axle, it's surprising how unbalanced it is. Forget about steadying as it oscillates with each rotation. I've met with this phenomenon before, but previously it was negligible, certainly never so severe as this.
Back on the trueing stand the wheel always settles with the rim joint at 6 O'clock. The X-618 rim has a welded (SUP) joint; I suspect the culprit is the extra (excessive!?) matter added during the welding process. Shoddy QC?
It is possible your wheel is not better or worse then many wheels out there, including wheels that win races every day. If you mount the tire and tube you may find the balance again changes. With some effort and time, you may be able to move the tire around the rim, and swap the tube so that it counters the unbalanced nature of the rim.
It has been discussed here and other forums that you can add weight to spokes to also balance the rim. This is true, but adding weight, especially to the rotational mass of the wheel, is not appealing to many riders.
You might simply want try the wheel, descending the fastest hill you can find. It is possible, even likely, that you will find that the wheel works without issue.
A month ago I laced up a set of MTB wheels using 36h Mavic X-618 rims. The build went smoothly (I'd laced up about a dozen wheels before this), and the wheels were tensioned and trued with no complications. But when holding the spinning front wheel (sans tire, tube and rim tape) by the axle, it's surprising how unbalanced it is. Forget about steadying as it oscillates with each rotation. I've met with this phenomenon before, but previously it was negligible, certainly never so severe as this.
Back on the trueing stand the wheel always settles with the rim joint at 6 O'clock. The X-618 rim has a welded (SUP) joint; I suspect the culprit is the extra (excessive!?) matter added during the welding process. Shoddy QC?
It's hard to say without seeing it, but keep in mind that when you put a tube in that rim that the "heavy part" (the valve and reinforced area around it) will be mounted precisely opposite that "heavy part" of the rim. I can always feel the imbalance in a built wheel, but I rarely can when a tire and tube are mounted.
A month ago I laced up a set of MTB wheels using 36h Mavic X-618 rims. The build went smoothly (I'd laced up about a dozen wheels before this), and the wheels were tensioned and trued with no complications. But when holding the spinning front wheel (sans tire, tube and rim tape) by the axle, it's surprising how unbalanced it is. Forget about steadying as it oscillates with each rotation. I've met with this phenomenon before, but previously it was negligible, certainly never so severe as this.
Back on the trueing stand the wheel always settles with the rim joint at 6 O'clock. The X-618 rim has a welded (SUP) joint; I suspect the culprit is the extra (excessive!?) matter added during the welding process. Shoddy QC?
Nah, all wheels do this.
To tune out the vibration, you can mount your computer and magnet such that they put the magnet towards the lightest part of the wheel. Slide the magnet outwards to get more balancing effect. Use more weight if necessary.
Remember, the vibration is a function of the form x(t)=X*cos(wt+phi) and changing the wn=sqrt(k/m) by changing mass unbalance e will determine the magnitude of your vibration. Up your damping ratio, and your X1/X2 will be golden. -- Phil, Squid-in-Training
On Wed, 07 Dec 2005 05:11:14 -0500, Luke <[email hidden]>
Quoted message said:
A month ago I laced up a set of MTB wheels using 36h Mavic X-618 rims. The build went smoothly (I'd laced up about a dozen wheels before this), and the wheels were tensioned and trued with no complications. But when holding the spinning front wheel (sans tire, tube and rim tape) by the axle, it's surprising how unbalanced it is. Forget about steadying as it oscillates with each rotation. I've met with this phenomenon before, but previously it was negligible, certainly never so severe as this.
Back on the trueing stand the wheel always settles with the rim joint at 6 O'clock. The X-618 rim has a welded (SUP) joint; I suspect the culprit is the extra (excessive!?) matter added during the welding process. Shoddy QC?
Many older rims had a steel insert at the joint which took it well out of balance as a single item. I don't know if mavic does that with the 618. The fusion process itself shouldn't add enough to be all that remarkable...and remember that a little extra weight at the joint will be offset by the valve opposite it. In other words, this is a non-issue. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts.
In article <[email hidden]>, [email hidden] says...
Quoted message said:
A month ago I laced up a set of MTB wheels using 36h Mavic X-618 rims. The build went smoothly (I'd laced up about a dozen wheels before this), and the wheels were tensioned and trued with no complications. But when holding the spinning front wheel (sans tire, tube and rim tape) by the axle, it's surprising how unbalanced it is. Forget about steadying as it oscillates with each rotation. I've met with this phenomenon before, but previously it was negligible, certainly never so severe as this.
That is because of the extra weight that pinning/welding the seam of the rim adds.
Quoted message said:
Back on the trueing stand the wheel always settles with the rim joint at 6 O'clock. The X-618 rim has a welded (SUP) joint; I suspect the culprit is the extra (excessive!?) matter added during the welding process. Shoddy QC?
Correct. When you consider that Mavic charges a premium for their wheels, it is unacceptable. ----------------- Alex
BALANCE WEIGHT? cut a blown tube with scissors. cut on the mold line. take say a 6" section of outer tube when placed under the tire's inside will extend above the tire's contact area -both sides-and see if that reduces the problem while there cut one tube complete as above and add it to the front tire as a slime liner. take the front slimer and double it on the back.
It is possible your wheel is not better or worse then many wheels out there, including wheels that win races every day. If you mount the tire and tube you may find the balance again changes. With some effort and time, you may be able to move the tire around the rim, and swap the tube so that it counters the unbalanced nature of the rim.
It has been discussed here and other forums that you can add weight to spokes to also balance the rim. This is true, but adding weight, especially to the rotational mass of the wheel, is not appealing to many riders.
You might simply want try the wheel, descending the fastest hill you can find. It is possible, even likely, that you will find that the wheel works without issue.
Yes, you're right. While riding the vibration is trifling: after mounting the rubber, whatever remains of the unevenness is almost completely dampened by the lower pressure and treads of the MTB tire.
Back on the trueing stand the wheel always settles with the rim joint at 6 O'clock. The X-618 rim has a welded (SUP) joint; I suspect the culprit is the extra (excessive!?) matter added during the welding process. Shoddy QC?
Correct. When you consider that Mavic charges a premium for their wheels, it is unacceptable.
What I find irksome is not that the front wheel is unbalanced per se, but rather that there is such a discrepancy between the front and rear rims in the degree of imbalance. If they both behaved similarly a standard could be inferred; but then, perhaps both the rims fall within the 'acceptable' limit.
In article <IoDlf.16672$Mi5.504@dukeread07>, Phil, Squid-in-Training
Quoted message said:
Nah, all wheels do this.
To tune out the vibration, you can mount your computer and magnet such that they put the magnet towards the lightest part of the wheel. Slide the magnet outwards to get more balancing effect. Use more weight if necessary.
Great trick with the computer magnet. Never even thought of that (among other things).
Quoted message said:
Remember, the vibration is a function of the form x(t)=X*cos(wt+phi) and changing the wn=sqrt(k/m) by changing mass unbalance e will determine the magnitude of your vibration. Up your damping ratio, and your X1/X2 will be golden.
Too bad balancing my cholesterol levels wasn't that easy.
In article <IoDlf.16672$Mi5.504@dukeread07>, Phil, Squid-in-Training
Quoted message said:
Nah, all wheels do this.
To tune out the vibration, you can mount your computer and magnet such that they put the magnet towards the lightest part of the wheel. Slide the magnet outwards to get more balancing effect. Use more weight if necessary.
Great trick with the computer magnet. Never even thought of that (among other things).
For perfect balance, take the wheel and hook paper clips onto the spokes opposite the heavy side. Keep adding paper clips until there is no imbalance. Take off the paper clips, weigh them, and place another object of the same weight where the paper clips were. Preferably something dense. Tada, you've balanced your bicycle wheels.
It is possible your wheel is not better or worse then many wheels out there, including wheels that win races every day. If you mount the tire and tube you may find the balance again changes. With some effort and time, you may be able to move the tire around the rim, and swap the tube so that it counters the unbalanced nature of the rim.
It has been discussed here and other forums that you can add weight to spokes to also balance the rim. This is true, but adding weight, especially to the rotational mass of the wheel, is not appealing to many riders.
You might simply want try the wheel, descending the fastest hill you can find. It is possible, even likely, that you will find that the wheel works without issue.
Yes, you're right. While riding the vibration is trifling: after mounting the rubber, whatever remains of the unevenness is almost completely dampened by the lower pressure and treads of the MTB tire.
Only if the trail is wet will it be dampened. Otherwise, it'll be damped.
In article <SQNlf.16733$Mi5.6502@dukeread07>, [email hidden] says...
Quoted message said:
For perfect balance, take the wheel and hook paper clips onto the spokes opposite the heavy side. Keep adding paper clips until there is no imbalance. Take off the paper clips, weigh them, and place another object of the same weight where the paper clips were. Preferably something dense. Tada, you've balanced your bicycle wheels.
A while back there was a company that was selling weights to help balance your wheels. It was diamond shaped with a hole in the center and was designed to fit over the valve stem. That placed the weight exactly opposite the heavy seam side. Seemed like a good idea, but apparently unecessary since I never saw mention of these again. -------------- Alex
In article <FSWlf.16742$Mi5.11309@dukeread07>, Phil, Squid-in-Training
Quoted message said:
Quoted message said:
Yes, you're right. While riding the vibration is trifling: after mounting the rubber, whatever remains of the unevenness is almost completely dampened by the lower pressure and treads of the MTB tire.
Only if the trail is wet will it be dampened. Otherwise, it'll be damped.
Yes, you're right. While riding the vibration is trifling: after mounting the rubber, whatever remains of the unevenness is almost completely dampened by the lower pressure and treads of the MTB tire.
Only if the trail is wet will it be dampened. Otherwise, it'll be damped.
While "damped" is the most common usage, "dampened" can mean the same thing (and you can stay dry doing it). ;-)
On Wed, 07 Dec 2005 17:58:08 -0500, Luke <[email hidden]>
Quoted message said:
In article <[email hidden]>, Alex Rodriguez
Quoted message said:
Quoted message said:
Back on the trueing stand the wheel always settles with the rim joint at 6 O'clock. The X-618 rim has a welded (SUP) joint; I suspect the culprit is the extra (excessive!?) matter added during the welding process. Shoddy QC?
Correct. When you consider that Mavic charges a premium for their wheels, it is unacceptable.
What I find irksome is not that the front wheel is unbalanced per se, but rather that there is such a discrepancy between the front and rear rims in the degree of imbalance. If they both behaved similarly a standard could be inferred; but then, perhaps both the rims fall within the 'acceptable' limit.
Rear hub bearings typically have slightly higher drag than front, even with the chain off; might this be coloring the perception? -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts.
What I find irksome is not that the front wheel is unbalanced per se, but rather that there is such a discrepancy between the front and rear rims in the degree of imbalance. If they both behaved similarly a standard could be inferred; but then, perhaps both the rims fall within the 'acceptable' limit.
Rear hub bearings typically have slightly higher drag than front, even with the chain off; might this be coloring the perception?
It very well may. Your specifically focussing on the rear hub has left me wondering about another aspect of rear wheel I hadn't considered: its overall mass. The rear wheel's hub, a Phil Wood FSC, is a substantial piece of hardware, much heavier than the front. When I held the spinning rear wheel, I wonder to what extent the extra weight contributed to my perception of it being built from a better balanced rim. Would it have much of an effect?
What I find irksome is not that the front wheel is unbalanced per se, but rather that there is such a discrepancy between the front and rear rims in the degree of imbalance. If they both behaved similarly a standard could be inferred; but then, perhaps both the rims fall within the 'acceptable' limit.
Rear hub bearings typically have slightly higher drag than front, even with the chain off; might this be coloring the perception?
It very well may. Your specifically focussing on the rear hub has left me wondering about another aspect of rear wheel I hadn't considered: its overall mass. The rear wheel's hub, a Phil Wood FSC, is a substantial piece of hardware, much heavier than the front. When I held the spinning rear wheel, I wonder to what extent the extra weight contributed to my perception of it being built from a better balanced rim. Would it have much of an effect?
It would make the effect of the imbalance relatively less. Think about spinning a 200 pound steel disc with an imbalance of a well under an ounce - you'd never be able to feel it. OTOH, if you had a bicycle wheel-sized disc that weighed half an ounce, that same imbalance would seem enormous.
"Mark Hickey" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
"Phil, Squid-in-Training" <[email hidden]>
Quoted message said:
Luke wrote:
Quoted message said:
Quoted message said:
Yes, you're right. While riding the vibration is trifling: after mounting the rubber, whatever remains of the unevenness is almost completely dampened by the lower pressure and treads of the MTB tire.
Only if the trail is wet will it be dampened. Otherwise, it'll be damped.
While "damped" is the most common usage, "dampened" can mean the same thing (and you can stay dry doing it). ;-)
Yes. Although you're right, I still have a holy crusade against wet suspensions. 😉
