Any research about this? I have heard that 650 are faster and then I have heard the opposite is true. It almost makes sense that 700’s are faster…less revolutions maybe?
Thanks!
KK
Well any speed that you pick up with the 650s will be negated because you travel further on them, you know because of more revolutions…just kidding, don’t have a clue
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It almost makes sense that 700’s are faster…less revolutions maybe?
Indy cars are really fast and tractors are really slow. Wheel diameter isn’t a factor. Any speed difference between 650 and 700 is insignificant.
650c is almost dead unless you are very short. It tough to find the same frame with a choice. I’m sure one size or the other is better, but the difference seems to be so small that available frames, tires, wheels, etc matter more
Styrrelll
650s are faster b/c you can get really fast aero wheels for cheap
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If you are a short person go with the 650’s.
If you need a bike bigger than a 50 go with 700’s
jaret
yes there is research
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all else being equal a 650 wheel will have more rolling resistance
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if you do not NEED a 650 bike in order to get into an optimally low position for yourself, then a 650 bike+wheel combination will be a tiny bit less aerodynamic, because the surface area saved by a smaller fork and wheel is being replaced by head tube or spacer, which is not as aerodynamic as your fork.
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all else being equal a 650c wheel/tire combo will be a tiny bit lighter
What this all adds up to though is almost nothing. If you are really short, a 650c bike will handle and fit you better and not interfere with your feet when you turn. get one.
if you are only a bit short, and you find a great deal on a 650c bike, don’t be afraid to get it.
Any research about this? I have heard that 650 are faster and then I have heard the opposite is true. It almost makes sense that 700’s are faster…less revolutions maybe?
Thanks!
KK
"yes there is research
- all else being equal a 650 wheel will have more rolling resistance"
Can you point me to that research?
jaretj
closest I can find at the moment:
http://www.schwalbetires.com/tech_info/rolling_resistance
wonder if AFM has ever tested it on rollers?
"yes there is research
- all else being equal a 650 wheel will have more rolling resistance"
Can you point me to that research?
jaretj
There’s no real way to do an apples to apples comparison with AFM’s techniques due to the fact that the control wheel needs to have similar aero properties to the testing wheel, which is not easily achieved. Even without wind on the wheel (ie. just air resistance), the results would be skewed too far.
Chris
Well we would only be looking to figure out the magnitude of the rolling resistance effect. If it is negligible then we forget about it.
if not we have to weigh it against the aerodynamic differences
another confounding factor is that roller testing and flat ground testing results differ in a relationship that depends on tire radius, so you would have to adjust for that. Equations to do so exist for car tires, dunno if it would apply to bike tires =0
science is hard
There’s no real way to do an apples to apples comparison with AFM’s techniques due to the fact that the control wheel needs to have similar aero properties to the testing wheel, which is not easily achieved. Even without wind on the wheel (ie. just air resistance), the results would be skewed too far.
Chris
700c is faster because they don’t make 650c Firecrest, dimpled or 23mm rims 
I guess I’ll have to settle for being slow with my HED Deep rear or HED Alps+Wheelbuilder disc cover.
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650’s have less spoke weight, rim weight, tube weight, and tire weight. Don’t know how many grams it all adds up to.
When I’m climbing McLean, Richter, the rollers and Yellow Lake, I like to think my 650’s have an advantage over the 700’s.
At least I keep telling myself that as I struggle up the climbs.
But if 650’s were faster, I think more people would be riding them, don’t you?
Seems like I heard, in most cases, advantages are negated by disadvantages, so it’s basically a wash.
I’m having a difficult time understanding how 1 sentence in that article is considered “research”
jaretj
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I ride 650’s on my tri bike. I push the pedals as hard as I can, but I am dead slow. I think it must be the wheels!
But if 650’s were faster, I think more people would be riding them, don’t you?
Seems like I heard, in most cases, advantages are negated by disadvantages, so it’s basically a wash.
In the mid-90s, 650 bikes made up almost half of the rides at Kona and they were one of the big fads in the early days of tri-specific bikes. Integrated headsets helped lower stack so more riders of relatively smaller stature can now achieve an aerodynamic position on 700c bikes. More tire/wheel choices are available in 700, and I haven’t seen clincher latex tubes in 650.
My uninformed opinion is that the differences in aerodynamic and rolling resistance between the two are much less than the resistance of a less aerodynamic position that may result if a shorter rider that can only get low on 650s is riding 700s.
Bottom line: if you can fit on either a 650 or 700 bike, the 700 will offer you more choices. If you need to be on a 650 bike, no wheel choice will make up for what you’re giving up from being too high up front.
Can you justify this statement with any data or research? Or even point me to a website or any other publication that does?
“Bottom line: if you can fit on either a 650 or 700 bike, the 700 will offer you more choices. If you need to be on a 650 bike, no wheel choice will make up for what you’re giving up from being too high up front.”
jaretj
I’ve done a zillion time trials and triathlon relays. I’ve probably done half on 650c and half on 700c. Generally, I’d say there’s no significant difference. I ultimately decided that there were coursed for horses and horses for courses. My 650c bikes always handled better and climbed better, so if the course was more technical, I used the 650c bike. On long and flat stuff, I always seemed to do a bit better when I brought out the big boy wheels.
I have a track record for my age group in the Lowes Motor Speedway time trial series. I set it on a 51cm P3sl with 650c wheels. Fastest race I ever did and I’ve owned a lot of VERY nice 700c wheels.
If you search this forum, you’ll find about 1,000 threads on this topic … if not more.
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Can you justify this statement with any data or research? Or even point me to a website or any other publication that does?
“Bottom line: if you can fit on either a 650 or 700 bike, the 700 will offer you more choices. If you need to be on a 650 bike, no wheel choice will make up for what you’re giving up from being too high up front.”
jaretj
There are two statements in my post. I assume that you’re referring to the second which is a generalization and based on the idea that 650c wheels allow a shorter rider to achieve a lower, presumably more aerodynamic position. Clearly, it depends on an individuals unique body measurements and fit parameters. What type of research would answer your question? Any research or studies behind your recommendation earlier in the thread that shorter people ride 650s?
You said this:
“Bottom line: if you can fit on either a 650 or 700 bike, the 700 will offer you more choices. If you need to be on a 650 bike, no wheel choice will make up for what you’re giving up from being too high up front.”
What do you base your opinion on?
jaretj