Bikerdrummer

I ride a road bike that’s 53cm, there’s a newer model with disc brakes that’s hard to find but I found one that’s a 52cm online, one size smaller.

With the 53 I have, there’s only 1” of standover room and the reach works fine. So I’d say it’s as large as I can go for this bike. Any larger and standover wouldn’t work.

The 52 will be an additional 1.5”’ of standover so 2.5”, and the reach is only 10cm difference which I can make up with saddle position.

Seems to me I’m on the low end of the 53 and top end of the 52, so should be fine with either.

Anyone else ever have this situation?

alcjphil

Not sure how 1 cm difference in frame size can translate into an additional 1.5" (3.75cm) additional stand over clearance unless the newer frame has radically different frame geometry than your current bike. Adjusting reach by moving the saddle back is not a good idea. Saddles should be adjusted according to the bottom bracket and reach by changing to the correct stem length.
Would be useful to know what bike models you are asking about

bruce19

This sounds like you need someone who can fit you to a bike.

ClydeClydeson

I am gonna go ahead and assume you mean 10 mm of difference in length. 10cm is like 4 inches, and that's I think more than the difference in top tube length between the biggest bike and the smallest bike in any one style.

Also, most models of bike are made in size increments of 2cm at best. Going to 52 from 53, if it were the same make and model of bike, is really only a half size difference, and most people can easily fit on up to three sizes of bike in any one model - generally there is an 'ideal size, and one size bigger and one size smaller can usually be fitted without too much complication.

If the other dimensions of the 52cm bike are roughly similar to those of the 53cm bike, then getting it to fit should be no problem. But don't assume that because the 'name' of the size is similar that the fit of the bikes will be similar.

Even if two different bikes had the same number denoting frame size (say, 53 cm) it perfectly reasonable that they could have very different standover heights. 1.5" different between two sizes of two different bikes is perfectly normal because the head tube length, top tube length, and amount of slope to the top tube can all be different.
To get a top tube 1.5" (~37mm) lower on a 1cm smaller bike, there would have to be either a shorter headtube, a lower attachment point on the headtube for the top tube or seat tube, or a lower bottom bracket, or some combination of these. It makes perfect sense, but the details are going to be what makes or breaks the fit for OP.

Phil_gretz

Starting with an ill-fitting bike and then comparing to another unknown bike without geometry/measurements, and then asking for what others have experienced. Hmmm...

Start with a fit calculator. Take careful measurements (have a friend help), and plug in to obtain results. Then compare any candidate frame to the recommended range of sizes. Measure and then compare.

Otherwise, have a competent bike fitter help. Hint: there are fewer than half "above average" bike fitters.

Bikerdrummer

There is a large difference in stand over and other measurements because the geometry changed when they switched from rim to disc brakes.
I’ve heard that happens. Not sure why.
I think the smaller one with disc breaks might actually fit better because of the difference in geometry. But can’t do a fitting because it’s only available online. Most LBS are still out of bikes in general.
If it doesn’t work out I can always resell it local.

Rolla

• You'll probably be fine on either, but it might be helpful to know what bikes you're comparing, so we can see the complete geometry charts.
• I'd be reluctant to use saddle positioning to account for the difference in reach.
• Since the current bike fits well, is the reason for the new bike simply to get disc brakes?

BikingViking793 

My size varies by bike brand...

Bikerdrummer

yea, just wanted a disc break bike.

Bikerdrummer

its an all city, trying to add measurements below.

The top tube 52 is the new one and 53 is the one I currently have.

sdimattia

For size chart comparisons, I find this site particularly useful at times . . .

https://geometrygeeks.bike/

Bikerdrummer

that’s so cool!

here is how the new one differs from the old: some things are smaller as it’s a smaller size.

Bikerdrummer

So according this this the standover is .9” lower so I’d have 1.9”. Seems reasonable.

RiceAWay

You want an experience so I will give it to you. I am 6'4" and ride a 25" (65 cm) touring bike. I ride a 24" (62 cm) steel road bike and a 23" (58 cm) new style road bike or cyclocross or gravel bike. In general the REACH is more important than the standover height given that you can raise the seatpost enough. I'll bet that you can ask anything about a bike and some person will tell you to go get a "good fitting". Are you too stupid to know that when you're stretched out on a bike and your arms are sore from leaning on them that you have to shorten the reach? Maybe you cannot figure out that your if you're rocking on the saddle it is set too high? If your knees are hurting that it is set too low? Fitting a bike regardless of those who believe otherwise is NOT rocket science that require specialists. The fact is that unless you're limited to the very smallest or largest frames, you can have a wide variation in bicycle sizes and still make it fit you.

Rolla

I'm confused. Are you looking at a 52cm Zig Zag? The geo numbers you posted as the 52 correspond to their 46cm frame.

sdimattia

To add to what seems to be the general trajectory of this conversation, if you're at the upper limits of a 53cm, then a 52cm should fit you just fine. It's usually easier to make a frame that is too small fit more comfortably than one that is too large. It'd be best if you could test ride a bike with very similar measurements to the one you are interested in buying. Just test riding a bike within your size range is a good way to get a general idea of what does or does not fit you.

Bikerdrummer

yea, a 46 has a 52cm top tube. Not sure why they call it a 46. I ride a lot but don’t pay much attention to numbers. The bike I have fits. After reviewing the comparable chart it looks like the newer one should fit fine.
I can’t test ride as they aren’t in stock local. The LBS’s are still very on inventory for all bikes. One told me they predict it will be like that for at least another year. :/
Good news about low stock is I’ll be able to sell for a good price if it ends up being too small.

urbanknight

Do not use saddle position to adjust reach. Use a different length stem if needed to adjust reach.

MAK

Correct. Whether you use KOP or some other method, you'll likely screw up your knees if you change saddle position fore and aft.

Rolla

They call it a 46 because All City's sizing is weird! I've never ridden anything smaller than a 54 in my life, but I'm shopping for a Super Professional and I can fit on either a 49 or a 52. Crazy!
I also think you're right about the resale value if it doesn't work out. Best of luck, and be sure to post pics when you get it.