# Fastback question?



## coasterbrakejunkie1969 (Sep 3, 2022)

I thought I previously saw a Fastback posted for sale that had a S-2 rear wheel. Does anyone know from experience weather it  would work? I understand they were intended to have 1 3/8 tires but just wondering if one  would fit. Thanks


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## Rollo (Sep 3, 2022)

I've seen a thread on here of it being done ... it's tight ...


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## stoney (Sep 3, 2022)

Probably could. I have seen where guys have spread and squeezed a 3” slick in the rear where a 2.125 was.


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## GTs58 (Sep 3, 2022)

I highly doubt you can put an S2 on a lightweight frame without some major modification.


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## Oldbikeguy1960 (Sep 3, 2022)

I did it in high school, with a straight true rim it will fit.
I saw a bike on eBay that a guy had used a Fastback frame to make a Krate style bike. It looked cool.
I also have a bike book that shows a Fastback frame made into a BMX with S-2 wheels.


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## coasterbrakejunkie1969 (Sep 3, 2022)

Oldbikeguy1960 said:


> I did it in high school, with a straight true rim it will fit.
> I saw a bike on eBay that a guy had used a Fastback frame to make a Krate style bike. It looked cool.
> I also have a bike book that shows a Fastback frame made into a BMX with S-2 wheels.



I was sure I had seen it before, I wondered if it was just for show in a sale post.


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## furyus (Sep 3, 2022)

Unlikely. If it could be done easily it would be commonplace, especially after all these years.


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## phantom (Sep 3, 2022)

I would try it. I think it would fit. I put a LW fork on my cruiser 5 to see if it would fit over a 2.25  It cleared but the caliper reach was off so I put the tange fork back on.


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## coasterbrakejunkie1969 (Sep 3, 2022)

furyus said:


> Unlikely. If it could be done easily it would be commonplace, especially after all these years.



I'm being told it has been done.


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## WillWork4Parts (Sep 3, 2022)

furyus said:


> Unlikely. If it could be done easily it would be commonplace, especially after all these years.



Ding ding ding!

An S2 rim will absolutely fit in the frame.
Any tire may go as well...it gets tricky when you go to put air in it and expect it to roll. A 1.75" tire may ride and not rub, balloon sliks don't cut it though. 

Would you like for me to demonstrate? I have a lightweight girls 20" frame... thinking it was a 65/6 Breeze.


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## GTs58 (Sep 3, 2022)

Sure it can be done. Where the tire would be located it's like 1-3/8" wide and a Typhoon tire is 2" wide not even fully inflated. Slide the wheel all the way back in the dropout and then use a skinny 1.75 tire on the S-2. Or leave as is with a Sting Ray 2.25 tire and pinch the tire in there and then just look at the dysfunctional bike. 😜  I've never tried to do this on a Fastback but I have lightweights and balloon models and by measuring I wouldn't even think of doing it, so you will have to do some funky things and see if you really can. I will say that for sure it will not just bolt in.


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## Oldbikeguy1960 (Sep 3, 2022)

Maybe I should try it...again. Like I said, I did it in high school around 1975 I do not recall doing anything out of the ordinary to do it. I will look for the publication I have with the BMX Fastback in it as well.


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## coasterbrakejunkie1969 (Sep 3, 2022)

WillWork4Parts said:


> Ding ding ding!
> 
> An S2 rim will absolutely fit in the frame.
> Any tire may go as well...it gets tricky when you go to put air in it and expect it to roll. A 1.75" tire may ride and not rub, balloon sliks don't cut it though.
> ...



I do not own a Fastback but I believe it is a longer frame then the Breeze. Here is my '72 Breeze with my S-2 with a 2,125 tire on it pulled all the way into the drop outs.. It is tight but it fits.If a Fastback is longer then it should work.


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## coasterbrakejunkie1969 (Sep 3, 2022)

I have some vintage 2,125 tires that would never fit in there, this is a newer slick.


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## WillWork4Parts (Sep 3, 2022)

Agreed, Fastback is a longer frame due to mag vs lucky 7 sprocket. Longer doesn't always change the taper though. I've got an aftermarket slick too that is marked 2.125, but it's molded more like a 1.75.


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## schwinnguyinohio (Sep 3, 2022)

Here’s one I had couple years ago with a 98/98 rear rim and a S2 fender squeezed in  with no rubbing , I do think a 99 rim isn’t quite as wide as a stingray S2 . I thought I had a regular S2 on it but I found my old post and it was a 98/99 instead. Rim was very true I remember with probably less then 1/8 inch clearance but didn’t rub , the chain I was using wouldn’t allow rim to go all the way back but it could have went back more giving more clearance I would think .


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## WillWork4Parts (Sep 3, 2022)

schwinnguyinohio said:


> Here’s one I had couple years ago with a 98/98 rear rim and a S2 fender squeezed in  with no rubbing , I do think a 99 rim isn’t quite as wide as a stingray S2 . I thought I had a regular S2 on it but I found my old post and it was a 98/99 instead. Rim was very true I remember with probably less then 1/8 inch clearance but didn’t rub , the chain I was using wouldn’t allow rim to go all the way back but it could have went back more giving more clearance I would think .
> 
> View attachment 1690182



The big question is which tire??


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## schwinnguyinohio (Sep 3, 2022)

Yea I was trying to remember if I used the 99 slik or something else .


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## coasterbrakejunkie1969 (Sep 3, 2022)

Well I guess it can be done as long as I do not get too greedy with the tire choice. I appreciate the help.


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## WillWork4Parts (Sep 3, 2022)

Here's an 1-3/4" tire on an S7 at 45psi.









Here is the Duro "2.125" slick also at 45psi. (I'm feeling dangerous today)











That tire definitely works on this frame, even with a 69 full width S2.

If it weren't raining I'd go out and get the 69 Gripper Slik from the garage....I'll do that tomorrow after I dig up a skinnier exerciser S2 that's still laced. Even with that I'm still skeptical, but I want to give it the benefit of the doubt being able to say that a rim stamped S2 and an actual Schwinn 2.125" Slik could fit.


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## coasterbrakejunkie1969 (Sep 3, 2022)

WillWork4Parts said:


> actual Schwinn 2.125" Slik could fit.



Yes I would love to run as big as possible but those original tires are big.


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## WillWork4Parts (Sep 3, 2022)

coasterbrakejunkie1969 said:


> Yes I would love to run as big as possible but those original tires are big.



I'm pretty sure they're *borderline* as wide as the 3.0" Innova Slick at the corners. Their squared off casing makes them that much "taller" when it's working into the Fastback and Junior chain stays' taper.


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## GTs58 (Sep 3, 2022)

Since the Fastback is a small wheeled 5 speed lightweight, it looks like the bends on the flair out are more drastic than the 26" model. This one has the wheel set to the rear of the drop out.


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## WillWork4Parts (Sep 4, 2022)

The first pic is the Gripper Slik on a M.O.Mfg rim at whatever psi I found it at. It's rim width is somewhere in between a regular S2 and an exerciser S2.



Second one is the same tire on a narrower exerciser S2 rim at 35psi.



100% interference at the chain stays with either rim. Roughly 1/32" clearance each side at the seat stays which would be just enough for me to be comfortable with riding the bike fenderless with a perfectly true rim. Interference at the chain stays would make for one heck of an exercise though for sure.

You could dimple the frame there, but I certainly wouldn't waste a Fastback frame for that....maybe a speedster or a damaged or otherwise undesirable condition Fastback.


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## coasterbrakejunkie1969 (Sep 5, 2022)

WillWork4Parts said:


> The first pic is the Gripper Slik on a M.O.Mfg rim at whatever psi I found it at. It's rim width is somewhere in between a regular S2 and an exerciser S2.
> View attachment 1690816
> Second one is the same tire on a narrower exerciser S2 rim at 35psi.
> View attachment 1690817
> ...



Thank you for the info


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## sccruiser (Sep 5, 2022)

Just run the duro slick. They are not as wide as the gripper.


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