WClark

Hello,

I am new to this whole world of bicycling. I have a very important question, if someone could advise me on.
I am seeking to purchase a road bike and am wanting to stick to trusted brands and well made bikes.
However, being on a budget, I am shopping for used bikes. I came across a brand "Giant", and the bike seems to be everything I want.
However, it says it is 48" size frame and I was recommended 49-52. Would this be a huge downfall or something I can make work? I am 5'4 with a 29" inseem. I hate doing the tippy toe dance, and want to find something in my comfort zone but comfortable fitting as well.
I don't ride a whole lot, but am seeking something maybe to ride 4 hours on a weekend day.

This happens to be the one bike that I feel has it all in my budget except the 48" frame. I am not sure if it is a big downfall for someone who does not race or ride daily competitions.

rms13

What model bike? Giants sizing is not conventional. Can you test ride it?

spectastic

in my opinion, when in doubt, go for the smaller size. there's usually more room for customization with a smaller frame by using a longer stem or more spacers in the head tube. the bikes these days usually come with extra long head tubes, so if a frame is too big, there's no way to lower the handlebar except with a super awkward -25 deg stem that's hard to find and fugly. seat height is really secondary. reach is most important. try to figure out your ideal frame effective top tube length. at 6', mine is 560 to 570 cm, supplemented by a 110 or 120 stem. there's always wiggle room. you can use a shorter stem on a larger frame, or vice versa. the main concern with stem length is the shorter stem will be slightly twitchier, but these are unnoticeable to non racing cyclists. stem angle, handlebar width, and crank length also play a role, considering the stock bikes usually come with different handlebar/crank dimensions with respect to different sizes.

roadwarrior

That is not how Giant sizes bikes. But a 48cm bike is really small, like for someone under 5' tall. But Giant does not size that way.

mulveyr 

Giant may use xs/s/m/etc, but they certainly do have numeric sizes easily available, for example:

Defy 5 (2016) | Giant Bicycles | United States

48cm is quite possibly entirely appropriate for someone OP's size; my son, for example, is 5'4" and is riding a 49cm Tricross, and it fits him perfectly.

bmthom.gis

Lol my wife is 4'11 and even a 43 cm bike is hard for her to fit.

exime

I think it depends on the manufacturer. Trek has it's own geometry guidelines for their customers and they are pretty darn accurate. I fell right into middle of a 54cm. I am just a touch under 5'8" but technically 5'7.75" or exactly 172cm.

WClark

Sadly the person selling this bike I wanted pulled it off the market.
However, I am in the same delima with a cannondale.

2013 Cannondale Carbon Synapse Womens | eBay


Not sure if if the 48" would still be a issue.


There is another few bikes I am looking at just don't know much about them
https://www.ebay.com/itm/Lapierre-roa...YAAOSwLzdWSO~B

exime

trek has a good chart. of course all manufacturers are a little bit different but this should be a good guideline. hope it helps.

bruce19

IMO rider height is an inadequate dimension to use to determine frame size. Back in the day (think Greg LeMond era) one method of sizing was to take .667 x inseam for a measurement. In your case that would be a 49. However, there are three traditional fits......Race, French and Eddie. They usually give a range of sizes that can be used. In my case 54-58. Different stem lengths required for proper fit. With the advent of sloping TT a sizing tool called "stack and reach" is being used by most fitters. I have come to believe that knowing your proper TT length (on sloping TT, "virtual" length) is a pretty good determinant. My 58 Masi and my 55 Guru are equally comfortable and efficient once the proper stem size/angle is thrown into the mix. Were I buying a bike from a shop I'd go to one that knows how to fit me and includes a fit in the price of the bike.

DrRobert

You are right to be careful and take your time. No worse mistake than finding out you don't have the best bike after 500 miles of riding. Or usually what happens is a person is riding the wrong bike and has adapted their riding accordingly. I've been on rides with people who have 5 or 6" of stand over space and I know the bike is too small for them, but of course, I keep my mouth shut they are perfectly happy riding a bike that doesn't fit them.

I'm certainly no expert, and others more knowledge please correct me if I'm wrong. You could to LBS, let them size you and try a bike just for experience. All this will depend somewhat on brands. You can also do it yourself. Much of the geometry of a frame is based on seat tube height (distance from middle of crank to top of seat tube).

Standover height is the first measurement I look at to see what size bike I should be looking at for a particular brand. You can use inseam, but this is kind of irrelevant because many sizing charts have no inseam category. The best way is determine your own SOH by holding a broomstick or something in your crotch (I use a level but make sure whatever you use is level) then measure to the ground. *Be sure you have your cycling shoes on*. This is the absolute upper limit. I usually subtract 2-3cm and use this measurement when looking at sizing charts. You can use this to rule in or out a particular bike. When trying a bike, again, put on your cycling shoes, standover the bike and see where the horizontal bar is. It can be snug but you should have at least 1" (2-3cm) of space there. Another simple way is to check it simply pull the bike off the ground until it is tight in your crotch and level. The wheels should have no more than an inch or two off the ground.

IMO (again no expert but I've bought a couple bikes) I stress standover height because this is directly related to seat tube length, which again, also relates to the geometry of the bike. The next most important is horizontal bar, but again, its going to be related to standover (which is essentially seat tube distance).

Keep in mind manufacturers are different, some size in cm's, some just s, m, l. etc. plus the geometry can be different. Also endurance vs. racing the models have slightly diff geomety. You need to look at the sizing charts for each one.

I also suggest you stick to a woman's bike, other may disagree. Women's bike geometry is not the same as men's. Many women can ride any bike, but if you are not a tall woman best to stick to woman's bike. This was told to me by a very knowledgeable bike fitter. The reason is the horizontal tube length tends to be a bit shorter proportional to mens'. I recommend you talk to a bike dealer or manufacturer tech support about this. I found this out recently when looking to buy a bike for my wife.

When testing a bike, I would take a set of pedals with you and a wrench to remove the old ones before test riding the bike.

Good luck hope this helps.

dksix

I don't think stand over is as relevant as it might have once been with compact frames and sloping down tubes of many modern frames.

rms13

Right. Stand over is the least relevant measurement. Top tube, head tube, reach, stack and angles are more important. Luckily we have an entire subforum on fitting and OP should probably ask some questions there or buy from an LBS that will fit them.

DrRobert

I said I was no expert but common sense tells me it is certainly not the least relevant.

If everything else is perfect for riding but you can't stand over the top tube you've got a big problem.
One that can't be altered with seat or handlbar adjustments.

rpenmanparker 

Another strike against common sense. With compact frames (sloping top tube) that situation is nearly impossible. That is why standover has become obsolete as a sizing determinant.

Lazyass

Don't think the OP is coming back. She started a similar thread in the general section.

DrRobert

Interesting. When I was originally fitted for a bike many years ago, they told me I have a longer torso/shorter legs than usual for my height and this is not an uncommon thing.

I was told to get the biggest bike I could get and still standover it because this would give me the best horizontal length for my body.

Maybe that's why I'm thinking the way I do, but it still seems to me if it was obsolete then why it SOH still listed in every geometry chart I've seen?

If a bike matches a rider's reach then is the chance 98% they will be able to stand over the bike? I don't know.

"Another strike against common sense" meaning what? It has served me well these 60 years. More than one bike fitters that I have dealt with the first think they do it tell me to stand over the bike!!

IMO (sorry, based on common sense) is regardless of top tube slope, there is a limited area which you will be standing over the bike.

The whole discussion is probably moot because for every rider I see with a tight or correct SOH, I see 20 with 5" riding bikes that are too small.