Wheels - the theory!

Sorting out your thrunge brackets, fettling your inter-rositers and even stuff about bike parts.
slimboyjim
Posts: 307
Joined: Fri Oct 03, 2008 11:17 am

Wheels - the theory!

Postby slimboyjim » Wed Nov 21, 2012 01:01 am

Hi,

I was considering whether to try a wheel build myself, lacing it up and getting a basic tension before handing it over to an LBS for 'proper' truing. The reason is that I really like the look of E-13's new TRS+ wheels but they are crazy expensive, and I was wondering how similar a cheaper-hubbed (Pro 2 EVO's) wheelbuild using the E-13 rims (or a similarly wide but relatively light rim) would be, particularly in reference to the stiffness of the wheel... I did a forum search and couldn't find what I was looking for I'm afraid!

I'm trying to work out what the main contributor(s) are for various qualities of a wheel so if anyone can advise me and/or direct me somewhere I can read up properly I'd appreciate it? That way I may be able to judge whether the more expensive options have a significant advantage or whether I'd be better off not spending money I don't have!

This is what I think I know:
Acceleration/braking - main factor is (rim) weight, followed closely by the spoke tension/pattern.
Ease of initiating a turn - weight of whole wheel is the predominant factor.
Strength - More spokes on a wheel distributes less load to individual spokes, making the wheel stronger.

Stuff I'm confused about:
Stiffness - I think the rim will be the predominant factor? Does spoke tension/pattern have much of a role? If so, how and why? I understand that a 32 spoke wheel will be stronger than a 28 hole wheel but would a 32 spoke wheel be stiffer in use? The E-13 hubs have large flanges that reduce the length of the spoke required and cause the leading/trailing spokes to lead/trail at a wider angle - would this affect stiffness?

So, relating it to my original 'wheelbuild' example - if I assume that the same rim and spokes were used in my custom build as the TRS+ wheels, but different hubs were used how would the wheel vary? Using Pro2 evo's as an example, I would understand that the Pro2 wheels would be slightly lighter (lighter hub) but as the weight loss is only at the hub the acceleration/braking would feel similar (perhaps slower due to longer spokes on hope hub wheel? I'm ignoring any differences in the number of points of engagement of each hub and assuming the spoke tension/pattern is similar...). However, the wheel may initiate a turn marginally more easily due to lighter overall weight, and using the same spoke count would result in similar strength between both wheels. Finally, I've no idea whether the stiffness of the wheel would be different between the two wheelsets...

I know it's (wheel building) a complex matter so thank you and sorry in advance!


James

User avatar
nicklouse
Lives Here
Posts: 80713
Joined: Thu Mar 20, 2003 12:14 pm

Re: Wheels - the theory!

Postby nicklouse » Wed Nov 21, 2012 01:11 am

the build is more important than the parts.
read Sheldons pages on wheel building.

and to the last part. you would not know the difference.

32 spoke may not be stronger than a 28 hole wheel.

have a read viewtopic.php?f=40073&t=12536562
"Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown

User avatar
ride_whenever
Posts: 13199
Joined: Tue Oct 17, 2006 19:31 pm

Re: Wheels - the theory!

Postby ride_whenever » Wed Nov 21, 2012 09:01 am

if you want to learn wheelbuilding, buy a bog cheap wheel from your lbs (the sort they throw out on cheap hybrids ~£30) and take it apart and put it back together a few times.

Then buy some decent pre-built wheels, either from your lbs or from hope etc. You generally wont save money building yourself unless you source 2nd hand parts or can buy at trade. So why risk having a slightly dodgy home built wheel when the cost will likely be the same!

On wheel building, read the sheldon brown pages, and also have a good read on here

Generally the build it the most important part of the wheel, deeper rims and higher flanges tend to build a stiffer wheel given the same quality of build. However spoke crossing has a far greater effect. Generally the more crosses the better up to the point the spokes run tangentially to the hub flange. Also the more crosses the harder the nipples are to turn as there is more angle as they leave the rim increasing the friction significantly.

User avatar
mrmonkfinger
Posts: 1431
Joined: Fri Sep 02, 2011 13:44 pm

Re: Wheels - the theory!

Postby mrmonkfinger » Wed Nov 21, 2012 09:22 am

slimboyjim wrote:Acceleration/braking - main factor is (rim) weight, followed closely by the spoke tension/pattern.


Rim weight is main factor, spoke pattern has practically nothing to do with it (providing its a normal pattern), tension has nothing to do with it (providing enough tension to keep wheel together under normal conditions).

slimboyjim wrote:Ease of initiating a turn - weight of whole wheel is the predominant factor.


Rim weight again.

slimboyjim wrote:Strength - More spokes on a wheel distributes less load to individual spokes, making the wheel stronger.


Build quality and sufficient spoke tension also influence strength. 32 spokes are plenty strong enough for 26" MTB rims.

slimboyjim wrote:Stiffness - I think the rim will be the predominant factor? Does spoke tension/pattern have much of a role? If so, how and why? I understand that a 32 spoke wheel will be stronger than a 28 hole wheel but would a 32 spoke wheel be stiffer in use? The E-13 hubs have large flanges that reduce the length of the spoke required and cause the leading/trailing spokes to lead/trail at a wider angle - would this affect stiffness?


Rim, partially, quality of build, mostly.
Yes, tension needs to be "enough". Pattern, not much.
32 spoke, stiffer, maybe but I doubt it will detectable. Rim deflection is influenced by the unsupported gap between spokes and also by rim stiffness, but the difference between 28 and 32 spoke rims will be small. Most support is provided by the spokes, again "enough" tension and the rim will be plenty stiff.
Spoke length won't make any appreciable difference to anything.


HTH

slimboyjim
Posts: 307
Joined: Fri Oct 03, 2008 11:17 am

Re: Wheels - the theory!

Postby slimboyjim » Fri Nov 23, 2012 20:53 pm

Just a quick thanks to all - that's a whole lot clearer now!


Return to “MTB Workshop & Tech”

Who is online

Users browsing this forum: No registered users and 4 guests