700C vs 27” Crazy Question
 

I purchased a vintage bike that when stock would have had 700c x 28 tires.

The bike I purchased is configured with 27”.

The current setup works fine but my OCD mentality is considering replacing the rims, tires, and brakes to 700 C.

Also I’m thinking the smaller diameter may make the bicycle more responsive when pedaling.

Questions:

Am I overthinking the slight diameter difference and secondly will an average rider be able to notice the difference if switched?

Should I simply put it out of my mind, save my money, and keep pedaling?

Thanks

missing parameters there.
if it works fine now, stick with it.
When you need tires, then think about it.
note that the brake pads most likely only need to drop 4mm to catch the 700c rim.

Over-thinking, maybe. Would you notice the difference? Very probably not. But...... with 700c you'll have a wider choice of tires. And it's really unlikely you'd have to change your brake set if you switch to 700c. And you might gain an extra few millimeters of clearance for wider tires (should you want to go there..).

All else being equal, there's no way you can tell the difference between the two sizes. Put it out of your mind. The only advantage to 700C is more tire choice. However, 27" Paselas are fine tires.

My 27 and 700c look the same. I agree with ^

Many Thanks
 

OK.

Thanks everyone.

I’m cool and will leave the bike as is. It rides great but I tend to be a worry wort from time to time.

There is a another good reason for going to 700c if you ride in the wet. More fender clearance; hence allowing bigger tires and more tread choices. (I try to buy 27" wheeled bikes as winter/city/rain bikes and set them up with 700c wheels. Now that gravel and other trends have happened, modern bikes with tons of clearance are available but for a long stretch, needing that clearance limited your options so I kept buying early '80s Japanese bikes and the like.)

If you can tell the difference between 27" & 700c when riding:
 

You likely don't need our help.

For me, a lot would depend on what the calipers look like. If the pads are at the top of the caliper arms, and they look kind of ugly like that, I would probably convert back to 700c. If the pads are closer to the middle part of the arm, I'd probably leave it alone.

I go back and forth with 27" and 700c wheels on all my bikes. Fat tires, skinny tires, sew-ups. Use them all and swap them from bike to bike. Been riding a mid 70's Raleigh Super Course with stock 27 x 1 1/4 wheels. Looking forward to see how it rides with sew-up wheels/tires.

The 4mm change in pad height effects about a 10% reduction in caliper braking leverage when switching to 700c, one more detail to perhaps ponder.

It's just the opposite though if the bike has canti's, where the leverage improvement can be quite a bit more than even 20%, and where the pad-dive angle (of pad trajectory) reduces pad clearance at the tire's sidewalls while also tending to drive the pad off of the edge of the rim (toward the spokes). So setup becomes more demanding, especially when the pivot post spacing is relatively wide and/or when the rim is relatively narrow (and narrow relative to the tire width), and when the rim's braking tracks are on the short side. I used very wide Module-4 700c rims with ~26mm tires on my Trek 720, and the braking power is pretty fierce now.

If nothing is wrong, put it out of your mind. No, the average rider wouldn't be able to tell unless there was a significant change in the tires. It would have zero to do with the rims. On the subject of tires, 1-1/4 is about the widest available for 27" at this time. If you want plush, supple tires, then you have greater options in the 700c.

+1

We succumb to appearance issues in one way or another.

But on that note, there are some calipers that fit 27" just fine, and are very close to touching the tire sidewall on 700c.
This is important, because if the pads do touch the sidewall, under heavy braking you are going to have flats.
Some Suntour calipers had a very limited range and this made some wheel switching difficult.

I have a few bikes that run 27” tires and they are fine. I use the Pamela tires that were mentioned and they ride great.

That's what Tommy Lee said! :D

You'll have a better selection of tires in 700C than you will in 27".

There is a distinct performance difference between 700c and 27". That said, I have to disagree with some of the comments or opinions of others. The 27". all things being equal, will feel somewhat sluggish when compared to the 700c offering. Why..?

Bicycle wheels, when spinning, become gyroscopes and the further the rim is away from the axle, the greater the gyroscopic effect. It is easy to understand the gyroscopic feel...

Take a bicycle wheel, any wheel. Hold it by the axle and, while keeping the wheel, more or less, vertical, tip if from side to side. Now, using the same wheel, give it a good spin and attempt to tip it from side to side. My guess is that the resistance to tipping will surprise you when the wheel is spinning. Now, double that effect, since a bicycle has two wheels, and you will know what a wheel with larger diameter rims has a more negative impact of ride feel. Also...

As others have suggested, tire selection for 27" wheels are, somewhat, limited and, in general, 27" tires and inner tubes tend to be heavier than their 700c rivals. The more weight one adds to the wheel rim/tire combination, the greater the gyroscopic effect. Hence, once again, the ride quality or feel in negatively impacted.

You should simply put it out of your mind, save your money, and keep pedaling !
Ok, the terms 27' and/or 622 may be confusing.
But in reality it makes no difference whether 27' tubular or 622mm clincher are mounted.

Technically Yes……But
 

Being the OCD over thinker that I am, this is exactly what I was thinking and my concern.

Technically I have no doubt that this is correct and in addition I would think that the larger and heavier wheel set would be a bit more sluggish to spin up from a start or when accelerating…..BUT

I’m not so certain to what extent an average rider can actually feel and tell the difference, hence my original inquiry.

Lightweight wheels in 27" are certainly doable if you wanted, but you'd be replacing so many parts that buying a set of 700C wheels would still make more sense. ;)

I have four bikes configured with 27" wheels and yes tire replacement is limited but not so much as to make getting new wheels to have a broader choice of tires. I would continue as is till ya can't find new replacement tiers anymore.

It's not like your trying to find a voltage regulator for a 48 Chevy... But that's another story... Ha

@ Basstar

Based on post #19, you suggest that the "average" rider would not notice the difference in ride quality. At best, I am an average rider and I most certainly do notice the difference in ride quality. To that add that many other forum members recommend going to alloy rims as opposed to steel hoops. Once again, the issue is the same - steel hoops weigh more than alloy ones and that extra weight does negatively impact ride quality. That said...

It can be argued that the lighter wheel does "spin up" more easily, however; the 27" wheel has a larger diameter than the 700c counter part. That would make pedaling a wee bit easier in the same fashion that a larger cog does.

I say these things out of personal experience and, as my wife of 53 years, will readily attest, I could be wrong. That said, do the wheel stationary and wheel rotating tip test that I suggested, then think about it. The first time I did the test, I was amazed at the gyroscopic effect. And, the faster you spin the wheel, the greater the effect. Try it just for fun.

Will they notice? I think people notice changes and initially respond to them, positive or negative. But then they start to deal with the change an go on to ride the bike. After a little time with the new parts, we're all back to normal.

Will they notice? Yes, at first.

Will they care? No, not after some time has gone by.

Speaking of lightweight 27" wheels, this topic deserves it's own little place to be explored. This is one of the themes of my Rudge Aero Special rebuild.