bolino

Hi!​​​
I'm looking for a a lightweight aluminium step-through/open frame. Any advice on which one and where to find step-through frames online?

ps: I'm new here and not sure this is the right discussion. Please let me know the right one otherwise.

Iride01 

Just the frame? Used or new?

Usually step-thru frames are on low dollar bicycles and are not generally in high demand. At least based on all the conversation I've heard and seen and imagined in my deliriums.

If it is only the frame you want, and you want new, then look at all the mfr's that offer step-thru bikes and see if they sell the frame only. Otherwise I think you'll have to exhaust all the used sources and probably buy an entire bike then strip and build it to your desires.

I have seen a few step-thru bicycles being ridden around here that looked nice and well suited to the use their owners were using them for. But these were already built bicycles. I think these in particular were from Specialized or maybe Trek.

bolino

Thanks. Just the frame. Used or new.

Barry2 

Oops OP wants just a frame.


Assuming a whole bike with step-through frame & Flat bars.... Try These

Barry

70sSanO

This is something I’ve been thinking of getting for my wife one day. I have enough parts and if there is something I need I’ll track it down.

I may have to buy a complete bike and strip it down, but the frame is still what is important.

John

bolino

I like Trek District 1/2/3/4 step-through and Specialized Sirrus 3. Also looked at Sixthreezero Evryjourney but the frame/riding position is not my style.
Anyway, still looking for frames only, if somebody knows about where to find that!

Iride01 

Well what's your style? No point in us recommending anything just to have them shot down for not being your style.

bolino

Do you know any website where I can buy aluminum step-through frames, whatever the style?

canklecat

From the specs I've seen, aluminum, step-through and lightweight don't go together. There's a lot of stress on the bottom bracket and even step-through aluminum frame folding bikes tend to be fairly heavy considering the overall size.

But a folder might get close to lightweight, if you don't mind smaller wheels. The Tern Castro was pretty interesting, with 24" wheels, not quite as small as most folders.

You're more likely to find a good deal on a good used steel mixte frame.

Several years ago when I was still recovering from back and neck injuries with limited hip mobility, I checked several fairly recent model bikes with aluminum frames and mixte or step through designs. The frame tubing was quite large in diameter and heavy. I didn't find any built-up bikes that weighed less than 30-35 lbs, some much more. Those bikes were mostly built for regions with flatter terrain where a 35-50 lb bike was still manageable even for older riders or those with limited mobility -- as long as lifting the bike wasn't a priority.

But in the 1970s-80s several makers offered mixte versions of their popular entry to mid level frames. Most were high tensile steel, a few seemed to combine chromoly top and downtubes with hi-ten forks and rear clusters. Those weighed right about 30 lbs and could be built lighter with careful selection of components. Mixtes aren't step through, but do have sloping top tubes to make it a bit easier to climb on and off.

bolino

Very interesting, thank you @canklecat! For whatever reason I love aluminum, so it's also a matter of feeling.

Flatforkcrown

Not aluminum, but step thru and light.

Iride01 

It's easy to find frames that are not specifically step through frames both new and used. However step through frames are apparently a very niche market.

If you want new, I can only suggest you find the style of step through frame you want on a bike already made and then find out if the manufacturer offers that as a frame only option. You might find a new frame offered by one of the sellers on Ali Express. For used frames, eBay, craigslist, facebook marketplace and others. And for used, an entire bike at the right price might be worth stripping and re-building.

But again, what's your style? eBay has plenty of used step through frames. Many for way more than I'd ever pay for a frame. Few if any I saw were aluminum.

bolino

Flatforkcrown nice, thanks! I don't live in the US (in Japan), but may I ask on which app/website did you find that, so I can look on a regular basis? I guess I can find aluminum ones at some point.

Iride01 Yes, it seems pretty niche indeed! That's why I was so unsuccessful until now I guess, and asking for some help here. Will have a look on Ali Express, eBay, facebook marketplace, thanks! About the style, since it seems so niche, I thought I shouldn't limit to a style before finding some. And I'm not even sure I have "a style"...

Flatforkcrown

I found that on eBay.

Iride01 

Well style can be either the looks and design of the frame for aesthetics or for it's intended use.

The more outside of just leisurely riding on smooth paved roads you get, the less step-thru even the frames called step-thru become.

Fredo76

Rivendell makes step-through steel frames - two models, I believe. My brother snagged the last 2021 Clem Smith Jr., one of the step-through models.

denaffen

The Bianchi Milano/Torino Dama are pretty light, but still only a pound or two lighter than a decent steel mixte or step through. And not available as just a frame.

Without knowing what sort of bike you want to build up, this is all guesses.

jppe

My sister bought a Momentum Vida low step complete bike and I think it has a lot going for it. I know it’s a complete bike but thought I’d share it. She does rides on paved surfaces near her houses for an hour plus and really likes it. I might look at getting my wife one.

https://www.momentum-biking.com/us/vida-low-step

canklecat

The only weight estimate I could Google for the Momentum Vida Low-Step is about 46 lbs. Does that sound about right?

That's pretty much what I'd have guessed for a step through frame sturdy enough to withstand the pressure on a bottom bracket with that geometry, although maybe a bit heavier than I'd have estimated. Most of them seem to use massive ovalized downtubes, and comparably oversized seat and chain stays, to ensure adequate stiffness and fatique resistance with aluminum.

That's why I'm betting the best way to get a relatively lightweight step through aluminum frame is with a folding bike. If I'm recalling correctly from browsing folder catalogs around 2015 or '16, there were step through folders weighing around 30+ lbs complete with wheels, etc.

Vintage Schwinn

Don't Laugh. Here is an example of an excellent 21 inch (53.34 cm) STEP THROUGH FRAME. Yeah, it is an electroforged Schwinn of course.
THIS ONE IS FROM THE LARGEST SIZE (21") SUBURBAN, and as you know the Suburban featured the Tubular front fork of the Continental.
(trading old stuff on EBAY who parts out schwinns has a great reputation, I've purchased items from him)
Anyway, it is just frame with the fork......No Kickstand, No crank, No Stem, No Seatpost, No Headbadge.....you do get the Chainguard..
You wouldn't care about the kickstand, as you'll save 2 pounds there, and you'd install a lightweight 3 piece bb set-up that adapts to the ONE PIECE's Housing.
No Joke, you won't find a more solid and stable STEP THROUGH frame than this SUBURBAN schwinn's. You could probably find one in your neighborhood for the same price or less, but heck for ~ $50 total shipped to your door, ah ya can't really beat that, and it is already stripped down of the stuff that you wouldn't want anyway.
WALD sells New 13/16" diameter seat posts in several lengths with the modern 7/8 top mount. You can get a Schwinn Seatpost clamp that is nice for less than $5.
The ALLOY (S) stem from a seventies era CONTINENTAL is lighter than the forged Steel traditional stem seen on Seventies era Varsity, Suburban & Collegiate etc.

'72 Suburban (JH serial indicates Sept 1972) Green 21" bare full frame including the tubular front fork(Suburbans & Continentals had this fork which is much lighter than the Ashtabula Forged steel Blade Fork on VARSITY/COLLEGIATE/BREEZE...etc and many many others)

https://www.ebay.com/itm/313662097423

I just don't think that you are going to gain much IF ANYTHING with most other aluminum or steel STEP THROUGH or MIXTE frames. Yes, you might save a couple of pounds in FRAME weight, but I contend that the SCHWINN frame is better by far all of them except perhaps some mixte frames which will be as solid and stable as the old Schwinn electroforged Step through. The great benefit is the strength and size of the (21) frame for a good size adult male. Compareably it is both longer wheelbase and larger than similar modern sized equivalents. The frame geometry is such that it is very stable and the angle of the seat-tube lends itself more to accomodating taller and larger Male adults if needed. THE GREAT NEWS IS THAT SCHWINN made a (19) step-through frame that also is comepareably larger and longer wheelbased than similar modern sized equivalents. Schwinn also made a small (17) step through version also.
I certainly would consider that as a possibility. Just obtain a SCHWINN bare frame, or if you find a free complete bike, etc.....STRIP IT DOWN SO IT IS JUST THE BARE FRAME, NO KICKSTAND, USE LIGHTWEIGHT 3 PIECE MODERN CRANK SET-UP, USE VERY LIGHTWEIGHT ALUMINUM 700C (622mm wheels) with perhaps 700C x 35mm tires......... You certainly want to INSTALL modern sidepull calipers IF YOU DON'T care for the old vintage WEINMANNS.
I would also while the frame is bare, I would prep and paint it a color of my own choosing......or have it powder coated assuming that color was a possibility. Heck, you don't need to let anyone know the frame came from a Schwinn if you don't want to. Anyway it is just a thought. I do think that if you judiciously select wheels and parts that you can easily get your final finished project weight below 30 pounds. Yes, perhaps that still sounds incredibly heavy to you, but practically speaking that is light enough to do everything you'd want to do, unless you race in Sprint triathlons or aim to maintain a 20mph average ride pace with the "A" group from the Local Bike Shop. Short of that, assuming you gear the bicycle decetly, and wide ranging enough, you'd have no issues going coast to coast and back with that step-through frame.
Yeah, step through frames & mixte frames can be a P.I.T.A. to mount on typical exterior rear car racks, without a specialty adaptor bar to aid & allow mounting.

jppe

I’ll see if I can weigh it some time. It felt a lot lighter than that when I picked it up.

Fredo76

Rivendell Clem Smith Jr. step-through frame

Although steel, my brother's new Clem Smith Jr frame, built up as shown, weighs 32.2 lbs. in total. And it's huge.

Wildwood 

Steel mixte frameset from
www.somafab.com

The Buena Vista is available in rim or disk brake version ~$600.

Wildwood 

Vintage Austro-Daimler Michelle



Size Large

Sy Reene

I'm just guessing, but you might be better off, just getting a complete bike and throwing away all the componentry/fork if you really want to. Eg.
https://www.bikesdirect.com/products/windsor/rover2.htm