BO15 Cyrus the Virus

Mar 26, 2012
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Is the smaller ring on the front of the Varsity a 39t ? That should work pretty well, and it won't be 'ramped' so should work well for a single speed. You won't have the leverage one does from a standard bicycle configuration, and yes, hills will be an issue. The small wheels in the back won't provide much momentum or 'carry' once you get it up to speed.
I'd say maybe a 21 or 22 t rear cog. And that still might be too much.
 

LukeTheJoker

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Mega range rear freewheel is your friend on these builds, getting harder to find in the thread on type though.

39t would be a good place to start if you have a 14-26 or there-abouts on the rear.
 
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Is the smaller ring on the front of the Varsity a 39t ? That should work pretty well, and it won't be 'ramped' so should work well for a single speed. You won't have the leverage one does from a standard bicycle configuration, and yes, hills will be an issue. The small wheels in the back won't provide much momentum or 'carry' once you get it up to speed.
I'd say maybe a 21 or 22 t rear cog. And that still might be too much.
It's a 5 speed.

Correction, it's going to be a 7 speed, I ordered the freewheel posted above.
 
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It's a 5 speed.

Correction, it's going to be a 7 speed, I ordered the freewheel posted above.
Wow. I completely missed that part of the conversation. :bigsmile:
Looking back, yes, the Mega range is a good one for, well, mega range. Make sure you have a derailleur designed to handle that big first gear cog.

mega range der.jpg


It has a larger than normal pulley wheel on the bottom. The Shimano Tourney is a good option, and they are usually relatively inexpensive.
 
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Wow. I completely missed that part of the conversation. :bigsmile:
Looking back, yes, the Mega range is a good one for, well, mega range. Make sure you have a derailleur designed to handle that big first gear cog.

View attachment 119587

It has a larger than normal pulley wheel on the bottom. The Shimano Tourney is a good option, and they are usually relatively inexpensive.
Would this one work?

https://www.ebay.com/itm/RD-TZ-31-Rear-7-speed-Hub-Bolt-Mount-direct/274347775840?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
 
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That's a direct mount style, where the mounting bolt threads into the frame or a hanger that hangs off of the frame. I'm guessing you want one that can fit into the dropout, and be held on with the axle and nut?

This is the one you want. Can't find any current ones on Amazon.


Note the hanger is held on by the axle and spacer behind fits into the drop out. What we call a 'bolt on' derailleur in the bike shop world.
 
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That's a direct mount style, where the mounting bolt threads into the frame or a hanger that hangs off of the frame. I'm guessing you want one that can fit into the dropout, and be held on with the axle and nut?

This is the one you want. Can't find any current ones on Amazon.


Note the hanger is held on by the axle and spacer behind fits into the drop out. What we call a 'bolt on' derailleur in the bike shop world.
I think the direct mount would be easier for me to make a mount for my axle housing. Don't forget, the axle on the trike spins, so there in no place to bolt onto. The direct mount attaches below the axle.

Would the one I originally posted work with the granny gear?
 
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Wow. I completely missed that part of the conversation. :bigsmile:
Looking back, yes, the Mega range is a good one for, well, mega range. Make sure you have a derailleur designed to handle that big first gear cog.

View attachment 119587

It has a larger than normal pulley wheel on the bottom. The Shimano Tourney is a good option, and they are usually relatively inexpensive.
Technically all new MTB groupset deraillreurs can run a big cog in the rear. Also a 32-34T is right now "Mega Range" only by it's archaic name :21: In today's standards you could consider 48-50T a "Mega Range"

@Psychographic - I had the same problem when riding my go-kart.
Original Stajli.jpg

46T on the front, 18T on the back. Barely ridable, good for only a distance of ~5mil. :confused:

My idea on it was to use a 7spd hub with coaster brake in the middle in the simmilar style as they do in modern trikes, but if you want only a one chain setup I would highly suggest 38T or even lower on the front and a MF-TZ-500 14-34T freewheel on the back.
 
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Not much progress. I thought the metal was out of my eye, nope still there.

I played around with positioning the BB, with it all the way to the front and sitting on the bottom tube, it's fairly comfortable with the low seat. It somewhat blocks the Roadkill Spear, but I guess I can't have everything my way.

P5050078.jpg
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The new rotors came, I'm pretty sure these will fit, but might have to be redrilled. The bolt circle is just a little too small to fit where the hubs need to be drilled.

P5050080.jpg


Still waiting on other parts that normally would have been here by now. Unfortunately nothing is normal these days.
 
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Here's how the scrap BB fits. The top curve on the BB is left over pieces from where the chainstays(?) go from two tubes to one. NEVER throw out those scraps!
After a little more welding I'll be skinning this side today.

P5070094.jpg



I needed a couple of tighter curves than what I bent on the 27" wheel.

Can you bend 5/8" tubing around a 20" wheel? Yes you can.

P5070090.jpg
P5070089.jpg


P5070096.jpg
 
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Since you are welding in your mounting point for the derailleur, I believe anything you chose will work as long as it has the travel "left to right" to cover the width of the gears you intend to use, because you'll be able to adjust the distance vertically and horizontally before you weld it in. Now obviously you'll want to reference the bike it came from (if it's used) or an existing similar setup. But I also believe you can increase the distance away from your axle somewhat to make sure it'll climb the tallest / easiest gear. I'd use the smallest derailleur I could find, as the clearance under the frame will be minimal...

GC.
 
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Have you ever looked at something and said "Dang, that is one sexy straight line!"

Of course you haven't, curves are sexy. So when I looked at the frame, the uprights to support the seat stays had to go. Now you know why I bent the 5/8 tube in the post above.

One upright replaced.

P5070097.jpg
P5070098.jpg


Both welded in place.

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