I'll say the Velotoze shoe covers.

Ding, ding, ding. Velotoze - $18, practically disposable (which is good 'cause they're easy to rip), and they've tested faster than anything else out there over and over again.

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Jim Manton / ERO Sports

You need a taller frame (or a raised seatpost and steerer spacers) regardless. Assuming the BB height remains constant, you need to get the extra height missing from the wheels somewhere. The exception on the spacers would be someone who is using a negative stem on their 700c bike.

I'd opine that 700c wheels aren't sized to the average male participant, they are sized based on a traditional standard. Plenty of big guys used 650c wheels back in the day (Dave Scott, 6'1" was a big advocate). It takes a relatively large advantage to get folks to switch to a new standard, and 650c just didn't seem to offer it.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

I fail to see how if you are 5 feet to 5'6" why you need a taller head tube with 650's....you just end up with a proportional head tube to the rider and to the wheels. That's all.

As for switching to a "new standard" Dan can chime in, but in the 90's in Kona in terms of wheel size it had gotten to the point where things were dead even

I wish I could find some pics of my Daccordi time trial bike that I used when I first attempted some triathlons in the early 90s. It atracted attention, but was a bear to ride with a 650/700 setup.

I seem to recall Greg Lemond did quite well at the Tour De France in 1989 on a TT bike with a 26" front/700c rear disc wheel, setting the record for the fastest time trial in Tour history, until last year when Rohan Dennis broke the record. The main reason the setup fell out of favor was because the UCI banned 'funny bikes' and the use of dissimilar wheel sizes, mainly in response to Graeme Obree twice breaking the world hour record on such 'unconventional' equipment.


I wish I still had my 'team issue' Tommasini time trial bike I had in the late 80's.

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¯\_(ツ)_/¯

First, I am willing to bet a head tube is much more aero than a wheel (no need to have a bad leading edge since it is not also a tire, also it does not need a trailing edge that is sometimes a leading edge, greater depth, etc,

Second, this is for people that can not fit on 700c bikes. That 700c has a frame that is too large to begin with, so the 650c with a smaller frame is exactly what you want. You do not need to make up for the smaller wheels, that is the point.

That is the key point.


Looking at Amber (below), she still has pad risers on her 700c bike. If the bike had 650c wheels, the extra stack would have to manifest somewhere (taller headtube, more spacers, etc.). I agree her fit doesn't look ideal, but from Jim's comments she's tested it quite a bit and it works for her.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

2X national time trial champ and she has to borrow a disc? Geez, it's rough out there.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

Why should the BB height remain constant? If we look at it from the point of view that a rider who needs 650c wheels to start with will automatically be using smaller cranks e.g. max of 165mm, then the BB can be lower (looking at it from a pedal strike point of view), so the rider will sit lower and won't need that extra head tube or spacers. I.e. is the reason for the longer head tube/extra spacers because of the higher BB in the first place - manufacturers having to accommodate the average 170-175 crank length? And obviously, the lower the rider can sit relative to the ground, in absolute terms, then surely the more aero?

BB height does not need to remain constant. It's independent of wheel size.
A company could offer its XS frame with a lower BB and 165s regardless of wheel size.

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ECMGN Therapy Silicon Valley:
Depression, Neurocognitive problems, Dementias (Testing and Evaluation), Trauma and PTSD, Traumatic Brain Injury (TBI)

Indeed, but that's not my point. My point is, is the reason why smaller riders are testing the same on 700c frames as 650c, because the 650c size isn't optimised for them? i.e. it is designed to accommodate the same size cranks as people will use on 700c frames? Hence, the same overall BB height (from the ground) and hence, the same absolute height? If BB height on 650c frames was designed around the fact that riders who need small frames will use 160-165 cranks, then surely the rider would have a lower absolute position, and how can that not test faster???

On a related side note, I've never understood why fitters never seem to mention BB height when talking about fit, as again, if you have two bikes that can be fit the same, yet one has a lower overall BB height, then surely that would create a lower overall position, and hence, be more aero? Am I missing something?

 . . national TT Champ and two wheel sponsors! :)

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Steve Fleck @stevefleck | Blog

"if you have two bikes that can be fit the same, yet one has a lower overall BB height, then surely that would create a lower overall position, and hence, be more aero? Am I missing something?"

the original P3 had a BB drop of 60mm, and i believe the speed concept has 80mm. these are 2 very obvious departures from the norm. i don't know that one of these is demonstrably better than the other. i hear what you're saying, but i've learned not to trust intuition overmuch when it comes to how a bicycle (mis)behaves in testing.

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Dan Empfield
aka Slowman

Thanks for chiming in.

Yes, for a given frame size (not wheel size.)

Good designers understand that smaller frames are for smaller riders, who often use shorter cranks, so the BB can be lower than on bigger frame sizes (and sometimes is). Regardless of wheel size.

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Other factors are much more important...in the end, you're just moving the big blob up and down with barely any change to the exposed area of the frame. Also, the lower the BB, the shorter the head tube needs to be for a given stack height.

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http://bikeblather.blogspot.com/

You clearly haven't read the Pinkbike comments section recently...


But seriously. There's a huge faction who hate 29ers, and who hate 27.5, and who hate the new wider "mid-fat" tires, because they're all an industry conspiracy to kill the 26" wheel and force everybody into the newest "standard" which itself will be obsolete in two years.

It's hardly far from settled that tall guys should use 29ers and everybody under 5'9 should be on something else. It doesn't even break down between XC and DH. And don't even get me started on the Boost 148mm hub standard.

my next bike is a 27.5 plus bike. just because they make a new wheel, that's not going to force anybody to buy the bike. you have a bike available that you can buy, but nobody's forcing you.

there's a lot of choice in MTB and that's a good thing as far as i can tell. we have less and less choice in triathlon bikes.

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Dan Empfield
aka Slowman

Oh, I'm in total agreement with you about choice. There are a couple main problems though:

• Compatibility: My old 26" wheeled bike is not compatible with any more current standard. It uses quick releases (virtually dead) and 135mm rear axle spacing (virtually dead). Want plus-size tires? Gotta buy a new frame and fork with Boost spacing, plus wide rims. Then you have to convert your drivetrain to the correct chainline. Then if you put normal size tires on, your BB height is screwed.
• Consumer choice: The availability of quality replacement parts is next to zero. Everybody says 26" isn't dead, but I have to settle for Nashbar leftovers -- and even then, the disc brake rotors are different, so I can't just use my old ones.
• Evidence: Limited testing shows that 29ers are faster for many real-world applications. But nobody has proven that they are faster for tall people, or only scalable down to a certain frame size, or that rollover benefits outweigh the perception of different handling traits. And people who think that 26 "just feels more playful" are never going to be convinced by science.

This is why everybody should just buy more bikes.

Proabably way off topic, but why did the MTB gang go to 650B instead of 650C when they wanted a tweener wheel size?

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Advanced Aero TopTube Storage for Road, Gravel, & Tri...ZeroSlip & Direct-mount, made in the USA.
DarkSpeedWorks.com.....Reviews.....Insta.....Facebook
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the MTB folks never were onto 650c. in 1987 i started farting around with bikes, and specifically 650, and when i ordered and got my first rims they were 559 bead diameter. the 571 bead was used very sparingly, by funny bikes mainly. MTB in 26" has always been 559m, from the get-go.

now, 27.5", i don't even know what that bead diameter is.

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Dan Empfield
aka Slowman

Supposedly, it is 584mm. Which is just 1% more than 650C.

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Advanced Aero TopTube Storage for Road, Gravel, & Tri...ZeroSlip & Direct-mount, made in the USA.
DarkSpeedWorks.com.....Reviews.....Insta.....Facebook
--

And only 12.5mm (< 1/2") larger on the radius (the "working" dimension in regards to wheel performance) than a 26" wheel :-/

The adoption of 650B in MTBs was (IMHO) only because after the bike industry realized that maybe not EVERYTHING was desirable to switch to 700C, they couldn't go all the way back to 26" because that would basically be admitting a mistake.

BTW, why is it called 27.5" when the diameter is only 25mm (less than 1") larger than a 26" wheel? Shouldn't it be a 27"?

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http://bikeblather.blogspot.com/

Thanks. I assumed good designers would, but so far I hadn't found any examples of lower BB heights for smaller frame sizes. And taking one example (it's hard trying to find companies that list full spec builds), Felt with their IA, I note that the BB height (drop 72) is the same across all sizes, yet they spec a complete build for the smallest size with 165 cranks, and the largest size 175

• Crankset:
  Rotor Flow Aero w/ Power 48cm = 165mm 51cm = 170mm 54 - 56cm = 172.5mm 58cm = 175mm
  

...maybe SuperDave will chime in on why they didn't lower the BB in relative terms across the range, to get the rider lower.

As a highly contented CAAD 9 rider, still looking forward to hearing the fruits of your work with Cannondale!