Wheel Size Facts Part 1-Dimensions, Weight and Strength

The boys over at Banshee Bikes sent this along today it is a good read on wheel size.

"You may have read certain online and printed marketing startegies which talk about wheelsize with a significant bias towards one size. The size they promote will always be either the only size that the source company produces, or the size that they want to push. Intentional marketing spiels are often very misleading and can skew the purchaser's judgement.

I feel it is my duty to set the record straight by writing a series of blog posts that kick off with this one, which addresses two key components of wheel size: weight and dimensions (and little bit of strength thrown in for good measure!). I plan to give unbiased information that you may find useful when deciding what size hoops you want your next purchase to be.

I can offer nonpartisan information (actual facts, rather than marketing blurb) as here at Banshee we offer all 3 mountain bike wheel sizes. We let the customer decide what they want rather than force it upon them, so have no reason to promote one over any other.

Every wheel size has its pros and cons, so picking the best wheelsize for you really comes down to personal preferance. The main things to consider when picking wheel size are your riding style, riding purpose (style or speed), the terrain you ride, and rider height, but there are also many other factors. I'll try my best to cover the main ones.

The following camparisons for this whole series are based on using Maxxis High Roller II 2.3" tires on each wheel size with same rim width for all sizes.

Any comparison I do will be relative to 650b wheels since they are the middle wheel size and so it makes the % change figures clear and consistant.

Dimensions: (Outer tire dimensions taken from official Maxxis 3D files)

Straight away this table is likely to cause some confusion... because as you can see, none of the rims or tires match up to their name sake. You can find out why this is the case by reading from a master of bike knowledge Sheldon Brown.

However, one point to notice is that while 650b is marketed as 27.5", it is only 1" larger diameter than 26", and 1.5" smaller than 29", so it is significantly closer to 26" than 29.  The 650b tire (often marketed as the 27.5") does not actually fall equally between the 26" and the 29" tires, so the characteristics of the 650b are far more similar to 26" than 29" wheels.


Weight:

Static weight

Obviously, tire and wheel build weights can vary significantly for all wheel sizes. So I'm sticking with 2.3" wide High roller II 3C/EXO/TR. For the wheels, I will use Stan's ZTR Flow EX wheels for each size.

Static weight (the weight of an unrotating wheel) is often emphasised by marketing teams. But it only really matters when you lift the bike on and off a rack or carry it on your back. However, static weight does have an effect on the...

Moment of Inertia

Moment of inertia is resistance to angular velocity change about an axis of rotation. Basically, the higher the moment of inertia of a wheel the harder it is to accelerate (and decelerate). This is far more significant than static weight when riding a bike.

Moment of inertia is related to both radius and mass, as Moment of Inertia (I) = Mass x Radius². A low moment of inertia results in a fast accelerating wheel (easy to start spinning). The flip side of this is that a high moment of inertia is harder to decelerate (harder to stop spinning), and so the wheel will carry the speed better once rolling if all other factors are equal.

The below table shows approximate moments of inertia by using the BSD as the effective rotational radius for all wheel sizes. 

What these numbers illustrate is that if you ride flowy trails that do not require lots of braking and accelerating back up to speed, then a larger wheel might be a better choice. However, if the trail demands regular braking and pedaling up to speed again then a smaller wheel might be better suited.

If using the same effective components, then as the wheel size increases the weight and inertia increase accordingly (as you would expect)... but because inertia increases at a rate that is proportional to the radius squared, it goes up more steeply than weight as the wheel size increases.

Strength:

A factor that is strangely often overlooked by marketing teams is that of the strength and stiffness of the wheel. I find this particularily strange as wheels cost a lot of money, and are subject to a lot of abuse, and personally the lifespan of a wheel is a significant factor to me when chosing what set to invest in.

If comparing like to like wheel builds (same rims, hubs etc), smaller wheels will always inherintly be stronger than larger wheels. This is due to wider gaps between spoke eyelets and poorer spoke triangulation etc. So strength to weight ratio is something that will always be won by smaller wheels.

It is however easy enough to compensate for this by getting stronger and stiffer wheels, but they do generally either weigh, or cost more. So something has to give.

It doesn't stop there....

Weight, dimensions and strength are obviously very important factors to take into account when considering what wheel size to choose. But... there are other factors too! And if this mini-blast of physics chat hasn't put you off too much, stay tuned for future blog posts about topics where bigger wheels have the advantage."

George and Neko Both Finish Top 15 at World Cup Finals

Perfect sunny conditions prevailed for the final World Cup race of the 2013 season here in Leogang, Austria, where Trek World Racing’s remaining uninjured downhill riders Neko Mulally (USA) and George Brannigan (NZL) had solid qualifiers Saturday. Neko had a career best qualifier coming in 7th place, and George had top 10 splits on his way down the hill, but 400m from the line had a crash which cost him time. However both riders went into the finals today knowing they had top 10 pace.

George went off about 1 hour before Neko and had a great run going. His run put him into the hot-seat as fastest rider at that point but only after unclipping his foot on the approach to the same corner where he fell in qualifying, crushing the family jewels.

“Yeah that was a pretty uncomfortable way to finish the run, but overall it was going well until then. I’m sure I lost a few seconds and even though I’ve ended up 13th for the day, I was having a solid top 10 run until that mistake. Considering I also hurt my shoulder in the crash yesterday and it wasn’t that good today, I do know the speed’s there and I feel 100% back to my best now”, said George shortly after leaving the hot-seat, where he sat for close to an hour.

Neko was on a great run as well and would have slotted into 3rd at the end of his run, and a guaranteed top 10, but lost 3 seconds in the final sector after making an error while pushing hard.

Neko said: “I knew I was having a great run, perhaps my best ever in World Cup racing and as I got towards the lower section of the course I made the conscious decision to keep pushing. Sometimes it’s easier to back off when you’ve had a great run for most of the course, but really great runs only come when you push the whole way. It can be riskier and unfortunately for me I did make that one mistake, but I’m glad I pushed for the result rather than be conservative. Finishing top 15 overall for the season was my goal, and today I achieved that”.

Team Owner Martin Whiteley summed up the Downhill season. “Injury definitely played a big part in our 2013 season. Aside from George’s knee recovery which we were aware of coming into the season, Brook’s shoulder injury before Andorra had a big impact for us. Then with Greg fracturing his collarbone and separating his shoulder in South Africa, it made for a tough time. Having said that, we have an awesome group of riders and there is strong team unity, and for me that’s very positive. Neko and George have done a great job these last 2 World Cup races and I know we’ll be back very strong in 2014.”

Next month Neko and Greg are planning to race in Mexico at the Taxco Downhill, and some other events may be announced in the coming days.

2013 UCI World Cup Round 6 Leogang Qualifying Results

2013 UCI Leogang Junior Men Qualifying Results

1	NIEDERBERGER Noel	SUI19950821	GSTAAD-SCOTT	3:42.018
2	WALLACE Mark	CAN19950601	DEVINCI GLOBAL RACING	+1.350
3	LUCAS Dean	AUS19950502	AUSTRALIA	+2.898
4	VERGIER Loris	FRA19960507	LAPIERRE GRAVITY REPUBLIC	+3.397
5	JONES Michael	GBR19950222	FMD RACING / INTENSE CYCLES	+4.774
6	GRAHAM Innes	GBR19960703	MS MONDRAKER TEAM	+6.075
7	ALGARRA NAVARRO Daniel	ESP19950314	SPAIN	+6.338
8	ESTAQUE Thomas	FRA19961115	FRANCE	+6.470
9	PIERRON Amaury	FRA19960304	FRANCE	+6.846
10	COLOMBO Francesco	ITA19951209	TEAM AIROH AXO SANTACRUZ	+6.916
11	ZABJEK Jure	SLO19951011	UNIOR TOOLS TEAM	+7.512
12	ZELLNER Siegfried	GER19950304	GERMANY	+8.606
13	ILES Jack	CAN19961007	CANADA	+8.754
14	GANNICOTT George	GBR19950311	DIRT NORCO RACE TEAM	+9.563
15	MCCORMACK Stephen	IRL19951028	IRELAND	+10.194

2013 UCI Leogang Women Qualifying Results

1	ATHERTON Rachel	GBR19871206	GT FACTORY RACING	4:00.974
2	RAGOT Emmeline	FRA19860527	LAPIERRE GRAVITY REPUBLIC	+1.579
3	KINTNER Jill	USA19811024	TEAM NORCO INTERNATIONAL	+4.123
4	CARPENTER Manon	GBR19930311	MADISON SARACEN DOWNHILL TEAM	+6.243
5	SIEGENTHALER Emilie	SUI19860919	GSTAAD-SCOTT	+8.651
6	CHARRE Morgane	FRA19900609	MS MONDRAKER TEAM	+8.720
7	NICOLE Myriam	FRA19900208	COMMENCAL / RIDING ADDICTION	+12.603
8	SEAGRAVE Tahnee °	GBR19950615	FMD RACING / INTENSE CYCLES	+12.697
9	HANNAH Tracey	AUS19880613	HUTCHINSON UR	+14.367
10	GATTO Micayla	CAN19880821		+17.650
11	GRIFFITHS Fionn	GBR19820827		+18.679
12	MILLER Miranda	CAN19900302		+19.542
13	CERNILOGAR Zarja	SLO19891218	BLACKTHORN GT	+21.859
14	AGER-WICK Anita	NOR19780831		+22.754
15	VERBEECK Vaea	CAN19901125		+26.409

2013 UCI Leogang Men Qualifying Results

1	SMITH Steve	CAN19891125	DEVINCI GLOBAL RACING	3:30.029
2	HANNAH Michael	AUS19831121	HUTCHINSON UR	+1.213
3	ATHERTON Gee	GBR19850226	GT FACTORY RACING	+1.263
4	BRUNI Loic	FRA19940513	LAPIERRE GRAVITY REPUBLIC	+1.935
5	BLENKINSOP Samuel	NZL19881028	LAPIERRE GRAVITY REPUBLIC	+3.250
6	BROSNAN Troy	AUS19930713	SPECIALIZED RACING DH	+4.025
7	MULALLY Neko	USA19930219	TREK WORLD RACING	+5.172
8	PEAT Steve	GBR19740617	SANTA CRUZ SYNDICATE	+6.040
9	GUTIERREZ VILLEGAS Marcelo	COL19900509	GIANT FACTORY OFF-ROAD TEAM	+6.258
10	BEER Nick	SUI19870917	DEVINCI GLOBAL RACING	+6.376
11	BRYCELAND Josh	GBR19900323	SANTA CRUZ SYNDICATE	+7.317
12	BEAUMONT Marc	GBR19840925	GT FACTORY RACING	+7.855
13	FEARON Connor	AUS19940119	KONA	+7.988
14	FIGARET Faustin	FRA19931107	TOPCYCLE BY TREK	+8.129
15	THIRION Rémi	FRA19900423	COMMENCAL / RIDING ADDICTION	+8.247

HC Racer

HC Racer are proud to announce the sponsorship of Elite rider and World Cup DH regular Jono Jones. Having represented GB in last years Junior World Championships, 19 year old Jono has moved up to Elite for 2013 and will be their dedicated cameraman on the UCI World Cup circuit and British Downhill Series.

This signing means that HC Racer will be creating it’s own dedicated content from all of the World Cups and British Downhill Series races that Jono attends. As well as capturing footage himself, such as this run from Fort William, Jono will also be arranging for guest riders to mount up and capture the action, the first guest rider being Brendan Fairclough at Vallnord, Andora.

This will give viewers the unique perspective of seeing the season through the eyes of the riders, watch the highs and lows of his season and follow his journey as he’s hungry for success, on HCRacer.com.

Season Goals

"Top 30 World Cup and top 10 National results in the first half of the season! After the worst beginning to a season I’ve ever had, with countless mechanicals and crashes in my race runs, I’ve pushed those forward to the second half of the season and hope, by keeping it rubber side down, I’ll manage to achieve this" Jono Jones."

What Is HC Racer?

HC Racer is the home of downhill helmet cam footage. They are tirelessly working away to gather you the best action from around the globe for your enjoyment and now with their first sponsored rider onboard, they are creating it as well!
 
In the beginning they will be creating and collating the best footage, but the site is set to grow! Currently, site creator Jamie Dyer is locked in a dark room coding in order to bring with you a truly unique site, that is set to be a true cycling multimedia community. Soon you will be able to get involved, find the best trails, improve your lines and learn from the best.

CHECK OUT HC RACER HERE

Two Top 15 Results at World Champs As Brook McDonald Retires from Season 2013

21 year old George Brannigan had his best ever result at a World Championship today here in Pietermaritzburg when he took 13th place, just one spot ahead of team mate Neko Mulally. The two riders looked solid all week and were happy with their performances on the demanding South African track. Meanwhile Brook MacDonald, who had earlier this week decided to end his season after this event so he can return home for important shoulder surgery, was unlucky to clip a tree and lose time, settling for 24th place.

For MacDonald the decision to return home has not been easy, but after getting further advice on the rotator cuff tear in his left shoulder, it's clear that he needs immediate surgery ahead of a recovery period of a few months. With an earlier start to the next World Cup season in 2014, the team supports Brook's decision to head home.

George, who himself has been on the road to recovery since he had knee surgery after season 2012, has been steadily rising back to his top form in recent races.

George said: "Both here and at Crankworx I've started to feel like my old self again. I thought it would only take a couple of races to get up to speed, but it has taken a fair bit longer. This is my best result ever on this track and I'm now really looking forward to one of my favourites, Hafjell in Norway in a couple of weeks".

Neko said: "When I arrived at the finish line today I was a little disappointed with myself because I still had some gas left in the tank. I needed to attack a little more and I guess that was the difference between 14th and a top 10. I'm still happy though and have learned from today's experience".

Both George and Neko will head to Norway in 2 weeks for Round 5 of the World Cup.