Jon B

Hi, I'm new to this whole bike moddin'. Coming from moddin' cars I thought this was gonna be easy- I was wrong. I got a pair of China Schwinn repops built in '06. I wanna add a seven speed(or more) to one. I'm completly lost on this whole Freewheel/freehub thing. I'll have no problem stretching the frame wider or welding brackets for the derailer. But I don't know what hub to buy. I know I need a 28hole? so I could keep my original 20" rim. I know I don't really want an internal cause I like the look of the derailer hanging down there. I have a Shimano 7spd derailer from a Mongoose 21spd I intend to use but taking the hub from that bike has provin to difficult for me(I've never worked on a bike before). Anyone know what I should buy as far as the rear hub,freehub? and sprockets? Do they have to be from the same company? I can't get the hub on the Mongoose away from the sprokets! Is any off that stuff of any value to me for my task? Help! Please!

StephenH

So what bike are you talking about in the first place? "China Schwinn repop" doesn't narrow it down much.

Jon B

Sorry, They're Stingray Krate types. Much like the originals. They don't have the sissy bar struts nor the internal hubs but they are re-releases with the springer Krate front ends.

mastershake916

Well, the spacing is totally different.
They made multi-speed sting-rays back in the day, model it after those.
Or just take a 20" bike with a 5 speed and use the parts from that one. I'd suggest going this route and selling the rear wheel whole from the sting-ray.
Also, I believe that the top one is the $88 BFK from walmart.

deez

Is that a BMW 850?

do I see racings Slicks and a recaro seat as well

nice.



Personally I say suck it up and go with an Internal geared hub for those, and maybe look on ebay for a cool stick shifter like on the 70's ones. There doesn't look like there's much room on the dropouts on those frames to drill a derailleur in there, I doubt you want to braze anything onto the frame, and without any wrenching experience you might find that working with rear derailleurs is a kind of a *****. You could lace up a sturmey archer IGH for pretty cheap.

Jon B

I have no problem with welding on the frame. I don't know that I could find a 36 hole front if I switch to 36 in the back. I planned on taking the rear frame section from a Mongoose and welding on the Schwinn frame. I kinda like the derailer look- (I'm also looking for a old steel spoke gaurd, doesn't have to be Krate original). I already plan on welding the frame and forks for those new stye cable brakes with two mounting studs. I'd like a disk in the front but I don't want hydrolic nor do I wanna spend alotta money on this.

Can anybody point me to a cheap 28hole hub and cassette, as a matching set I should buy. Or even a derailer to if no one knows of a set for the 7spd derailer I have. Like spit out some facts and part numbers, cause I'm not really bike savy, but I'm pretty capible when it comes to welding and stuff. I don't know what fits with what. Should I just try to weld up and redrill holes on a 36hole hub?


Both bikes are Wallmart specials. The car is a Nissan 200sx widend 8". The seat is no Recaro-It's a display model APC from a local speed shop the the guy's cat had it's way with-I try to keep the 200 affordable.


Thanks guys!

griftereck

be easy to get a wheel from a kids mountain bike.
but its probably a 36 spoke wheel

the frame you have will likely be 110mm wide at the wheel slots on back
it needs to be widened evenly on both sides to around 130mm
I have widened frames before by lying the bike on its side on the ground and stepping on the lower drop out and pulling the top side. Some small frames are a bit strong to do that.

My prefered method now is to strip the bike down and clamp the bottom bracket, the hole in the frame that the crank goes into. In a vice. Then lever the frame wider with a scaffold pole against the seat tube.
This method is easier to get right. If you pad the tube with cloth it wont scratch the frame.

If you want a 28 spoke hub with a cassette. That'll be a racing part. Look on ebay for one. Maybe a Time trial rider selling stuff.

Alternatively. If your wheel is a plain single speed. You can fit a longer axle and redish the wheel. A 7 speed freewheel will screw on.
Be a bit complicated to do.

You might not need to weld anything to the frame. As a rear gear mech will fit to the frame with a claw bracket.
Be better if you weld cable stops to the frame. But you can run a full length cable outer.

Jon B

I started some mods- I did the seat shocks, but had to weld to sissy bars together for my 6'2" body, so the chromes a little messed there. I'll get pics of that later. I think I'm gonna try for a Shimano Deora hub,derailuer, and cassette, next week. I started on hand brakes as I will no longer have a coaster;

thurstonboise

I'd go with an axle mounted derailleur like this.

deez

Cool project, keep us upto date with some pics

griftereck

some deraileur mechs come with a detatchable axle mounting claw thing.

the deore one doesnt though.

but if you get hold of one. They are standard thread. 10mm X 1.25 pitch.
so will take any mech, that bolts on.

got a few in the spares box at work
would give them out free if anyone asked. So think other bike shops would to

Sammyboy

You can buy the claw from Harris:

https://harriscyclery.net/itemdetails.cfm?ID=963


No need to be welding things. Before you go respacing the frame, are you 100% it's steel? Trying that with an aluminium frame will do bad things, so check with a magnet if you don't know for sure. Why not go for 36 hole? Is it a problem? You could have a 36 rear and a 28 front, perhaps? If you're going to respace, you could do it more carefully using a threaded rod the same diameter as an axle, and some selected nuts/washers inside the dropouts. This will give you a more predictable result than taking a scaffolding pole to it, without costing lots of money or time.

Jon B

O.K. I got some new stuff;


Anyone know how it goes together?

I still gotta make a stick shifter.

Jon B

OK- New problems; The chain size is different, requiring me to switch sprokets, or change to a three-peice crank.

Does anyone know where I could get a bottom bracket conversion kit?(cheap).

Or should I just just the bracket out of my parts bike and try to weld it on my schwinn frame?

musicman

like this? https://www.bicycledesigner.com/defau...umber%3D503013

Jon B

Thanks Musicman. But before I do that, can I just weld this in the existing bottom braket?


Do I just tap those chrome bearing races outta the braket?-The one on the bike, I dont see and welds or screws. They're not threaded in there are they?

Also I'm lookin' at 27 gears, to many? But I also want a stick shift.

If I make a shifter that moves three gears for every one front gear I only have three speeds, not enough.
Possibly I could slot the one cable lock screw so it stays untill every third gear in the back!?-not a good explanation, I should probably draw a picture.

Maybee I'm stuck with two shifters. Any Ideas

musicman

You should be able to tap them out, they look like they're just the standard pressed in races.

basscadetz

those will tap out.

here's one thats cheap:

https://www.choppersus.com/store/prod...onversion-Kit/

Jon B

I gotta an easier Idea for the shifter; Z gate.

1-9 rear derailuer works front to back, that hole assembly piviots left to right that works 1-3 of the front derailuer. I'll gate it like a Z so that 1-2 front derail shift is only available in 3 or 4 of the back, then 2-3 front is only available in 5 or 6 of the back.

Doesn't sound too hard to build.

What'da think?

griftereck

you'll have super low gears on a 20" wheeled bike.

you get cheap mountain bikes that have triple rings on a 1 peice crank. You could have got there chainrings.

Ive got an old Raleigh mtb that has that conversion kit as standard. Its getting a 1 peice crank then getting sold. Keep the bb for something more interesting.

I also got a bb conversion cups that are made by DMR. There machined alloy rings that have bolts that hold them together. Then an English BB set will screw in. They are reasonably thick. Think theres a lot of difference in size of a 1 peice and a 3 peice bb. Never measured them.

Jon B

Yeah, The bike my triple rings came of of is a 24" MTB. One crank sprocket is larger and three hub sprockets are smaller so there is going to be some higher gears, but not many. I figure with the euro-crank I could find a taller gear set later.

Another problem is the springer front end. At high speed it's unstable, the parts aren't tight enough tolerence and it wiggles.

So there's some problems yet to be worked out yet. But I'll get them.

griftereck

Im looking for a Shimano road triple chainset.
these have rings in 52 42 30.
I think

the older ones Ive seen are square taper..newer are octalink that wont fit on that conversion axle.

MTBs typically have 48 38 28. Maybe smaller on newer bikes

Still low gears mean good wheelies.
but more chance of breaking the chain

Sammyboy

You really won't need that 30t ring on a 20" bike

Jon B

It's been a while. I didn't get my wheel done for quite some time, and I screwed it up. I'll get to that in a second. But first som pics mock ups;



I had a problem with the chrome spoke protector, a part I had to have. The protector had no provisions for catching the spokes and it just sorta floated and ratteled around. I, not giving it much thought, and being a professional rocket welder decided to tack the protector to the spoke and melted one. Kinda sucks but I think I can get it welded to the point where I can re-true the wheel.

I still gotta do alotta stuff, including the shifter. I think I'm gonna stretch the springer spring cup out a little to give the forks a forward rake.