Can someone please tell me what the difference is ???
Yes. I know it’s 50.
Is there a difference in performance?
I’ll have a go at this, since I have ridden both. I am going to start with our esteemed slowtwitch publishers opinion that 650c is good for smaller bikes and 700c is better for larger bikes. His issue has to do with the height of the head tube. In short if you have a smaller frame, a 700c won’t allow you to have a head tube low enough to obtain a good position on the bike. I think he says around 54 centimeters frame size is where it can go either way.
I have raced on both sizes and found no discernible differences. The only advantage I would give one over the other is the commonality of 700c. They are much easier to find tires and tubes for just about anywhere. In 650c you can find good equipment, but you have to hunt more and expect you won’t have as much variety from which to choose.
Chad
P.S. The actual physical difference is the 650c has a slightly smaller circumference. It means you can use few spokes and the wheels are pretty tough. I think you would have a pretty hard argument to say one was faster than the other.
I know this is basically irrelelvant to tri, but the 650s DO accelerate easier. When I had my track bike built, I went with 650s for this very reason. I do notice the difference in this case.
Really appreciate the information. I am 5’7" and ride a size 52 bike. It looks like I can probably use 650’s as well as 700’s. I am looking for a new bike right now as mine was trashed in a July accident. This information will defnintely help.
Thanks ,
Jason
I’m 5’9" and I ride a 53 650c bike. As the wheel circumfrence is smaller on a 650 than a 700 the gearing you use will “shrink” accordingly…ie if you run a 53/39 up front (like most road bikes) and a 12x23 in the back on both bikes, the size of you gear will be “smaller” on a 650c. Ok, so I didn’t explain that too well. Think of it this way, the distance your bike will travel with one revolution of the pedals is farther on a 700 (due to increased wheel circumfrence) than it is on a 650 assuming you use the exact same gear. I tend to agree with many of the posts on this site that says most of us are overgeared. Certainly there are exceptions but the average age groupe triathlete doesn’t need the same gearing that a pro roadie is going to use. That being said, I find that using 53/39 chainrings on a 650 tri bike is analogous to using a compact crankset on a 700 bike.
Also, total agreement about the aforementioned comment about the 700c “community”. It’s very easy to get wheels, tires, tubes etc. for a 700, not always as easy on a 650. Lastly, on smaller frames 650’s seem to fit better. 47cm bikes with 700 hoops just don’t look, and I suspect handle, right.
Miguel in the 'No…El Tribato
No noticable performance difference. The difference is much poorer support for 650’s in terms of tires, tubes, etc. If you are in the middle of nowhere, you may be out of luck if you need a spare. I’d recommend 700’s unless you “need” to ride 650’s (i.e. very small frame).
I ride a 51cm 650c Cervelo P2K for TTs and a 54cm 700c Cervelo Soloist for the road. The 650c frame size enables me to get in a low, aerodynamic position on the bike. 700c will not do this. I am 5’8", 146 lbs with a 29 inch inseam. The 51cm 650c Cervelo P2K fits me perfectly. In contrast, the 54cm 700c Cervelo Soloist (with it’s compact geometry) fits me perfectly for the road – when I don’t need to be a low, aerodynamic position. The compact geometry with 700c wheels allows me to sway the bike efficiently back-n-forth without my thighs hitting the frame when climbing out of the saddle. This is not the case with a standard frame. My thighs hit the top tube and it’s very annoying. I would use 700c wheels on all my bikes but I just can’t get low enough to TT on a 700c frame/wheels at my height and small inseam. 700c tires and tubes are much easier (and cheaper) to find than 650c. BTW, a 650c tube will work on a 700c clincher, but not the other way around – in my experience.
~ AB ~