Base 28/29" wheel size on rim size

This discussion has an associated proposal. View Proposal Details here.

Comments about this discussion:

Started

I am in favor of updating the Standard 28/29" definition for Road Races in the rulebook. Instead of basing it on the entirely arbitrary 768mm, we should instead base it on a very standard rim size of 700c rims (622 BSD).

I see several advantages here:

  • 700c the standard rim size used in road cycling and is currently the rim size that everyone is using for their 28/29" unicycles.
  • Riders can choose to use any tire they want without it being unfair. A rider can you a smaller tire which is lighter but doesn't travel as far per revolution, or they can use a bigger tire which goes farther but is heavier.
  • We will never have a few rides build a custom 30" super light unicycle that still fits under the 768mm guideline. This is basically what has happened in track racing, and I think it's really silly.
  • You don't have multiple definitions of the wheel size. (IUF says 768mm but the Düsseldorf marathon always had a different number.)

I don't see any reasons against this change.

Note: There is a separate discussion about Standard 29" crank size. Please keep that discussion there.

Comment

I am all for it! For every single one of the reasons you mention.

I looked at all the biggest tyres I could find and they all came in well under 768mm, which means you can technically build custom wheels that go right up to 768mm.   That would make the standard class anything but standard, because no one will be able to buy off-the shelf parts.

Before Unicon 17, I did a fair bit of experimenting with 700c and 29" tyres, and, so long as you can pick crank lengths, lightweight/smaller diameter vs heavy/larger diameter, works out about the same.  It is nice to have that choice.

The 622 BSD is a good standard because it is used extensively in the bike industry (unlike 24" or 36" rims)- so is unlikely to disappear in a hurry.  People have thousands of parts to choose from.

Vote yes from me."

Comment

Going with BSD is a fantastic idea.  It also solves the problem with measuring tires which may have been legal when new, but stretched a bit.

Just a side note, there are some 622BSD tires which are above the limit.  The new 29+ platform  Surly Knards are listed at 772mm when mounted on a 29mm wide rim.  Once again though, these are not high pressure and they are 3in wide so a rider would have to make the choice of larger or lighter.

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I don't know enough about this matter to add anything to the conversation, so I will vote with the cool people who wear tights.

B.

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I'm with Benoit on this. 

Comment

I do have a question though. Is this easy to measure before races? Currently you just put it in the box thing. How would you measure rims accurately and quickly?

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Good question Jamey.

Tires are labeled on their sidewalls with the BSD.  26" tires will say 559, 700c/29" tires say 622 in parentheses.  Not that it's super scientific, but it's not too difficult to tell by a visual inspection.  32" wheels are becoming available in a very limited supply, but are not gaining a lot of ground in the bicycling world.  The 622 BSD is very common and the largest of the widely embraced by the biking community wheel sizes.

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Question for Benoit: If they're all wearing tights, how can you tell which of them are the cool people?  :-P

This seems to make sense to me. Only two snags that may pop up. One is people who think it's too loose. The other might be people with smaller wheels that don't have the BSD printed on the tire. I don't think either would amount to much of a problem The next size down from "29" is quite a bit smaller so there shouldn't be any confusion. As always, it should still be a maximum. In other words, the size for this category would be BSD 622 *or smaller*. Unless it's a situation where we are only allowing tires that are larger than the 24" maximum.

I like the idea of going by rim size. It makes things simpler, and also gives people a wide range of tires to choose from. You can go lightweight and skinny, or larger diameter with a weight penalty. People can ride what works for them. And that includes the 772mm Surly Knards if we switch to this rule. Those tires must be pretty heavy!

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@John, I go for with the most colourful ones obviously!

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Proposal sounds good. Do you think we need to mention the possibility of a minimum wheel size, for events where a smaller wheel category exists? Such as in a 10k that also has 20" and 24" categories. Or just let those smaller wheels enter if they are silly enough to want to?

Also I suggest moving away from the possibly-confusing term "Standard 29" Unicycle", which for most people would require finding another definition to know what it meant. Basically for our purposes it means "without gearing", I guess.

Comment

I would not add a minimum wheel size, let people decide by themselves. (There may be a cutoff time though.)

I also agree with John about the confusing name of Standard 29" Unicycle, if only because of the confusion with 28". Perhaps we should call it something like "Standard 700c class"?

Comment

Actually I was referring to the word 'standard', which most people only associate with Standard Skill. But 700c is also outdated. It should be called 29" Track or something similar. 29" is the nominal wheel size, and encompasses any smaller size. Track is appropriate in relation to the 20" and 24" wheel sizes that are used in 10k and/or shorter races. Those wheel sizes come with a built-in crank restriction also, while 29" does not. I'm okay with that. Or we could call it 29" Ungeared, but then we should call the smaller sizes that as well.

I'm also not sure about 'Class' either (sorry Klaas). That's another word we don't use elsewhere, so can we instead just call it a category?

For Road Racing we have the following possible categories:

  • 20" Track
  • 24" Track
  • 29" Track
  • Ungeared
  • Unlimited

The above allows the possibility for a host to add an Ungeared unlimited category if they want. If we give it a name, it will be less confusing later on when it happens.  :-)

Comment

Isn't it silly to call our Road Racing categories something with "Track" in the name? We have Track Racing and Road Racing separated out, two years ago. So why not omit the word Track?

I think 29" is just a colloquial name for fat 28" tyres. Most if not all tyres that we call 29" tyres are officially/nominally 28". This may be confusing, and therefore I like 700c as a name. And I don't get why 700c would be outdated. Also, 700c or 28"/29" don't encompass smaller sizes unless we include those in the definition.

Class or category: either is OK with me :-). But why is "category" better - do we use the word "category" elsewhere?

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I'm sorry but I still think it is silly to have 5 different categories which you then again divide into age groups..

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John...how is 700c "outdated"?  It is by far the most common wheelsize in road racing, and there are many, many, many orders of magnitude more 700c wheels than there are mountainbike 29" wheels.

Both 700c and 29" wheels use the same rim size, BSD 622

 

Comment

From the bicycling side of things, 700c is typically used for Road and Cyclocross designations.  29 is the same rim size, but used in the Mountainbike world.  Even there the 700c has lost its meaning as it's a rim and tire in conjunction to get that size.  Different size tires deviate from what that standard originally was.

However, cyclists understand what 700c means.  It's been called that for a long time.  Rather than invent a new term, it probably is best to stick with the most widely recognized one.

I think using 700c is a great way to designate the size and avoid the 28"/29"/700c controversy.  In the US we rarely use the 28inch designation, but it seems to be popular elsewhere in the world.

 

As far as the 5 categories go, with age groups, there really are only 2 or 3 available to all, Standard 24" (but may not be a class in longer than 10k racing), Standard 700c, and Unlimited.  Ungeared is only a subset for the fastest overall top 3 ungeared riders, and 20" is only for youth.  The number of participants seem to support 2 full classes with age groups for the 10k and Marathon.  Once again, the 24" doesn't seem to make the cut for the Marathon (and 100k if it comes around again.)

Comment

I support all of that.


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