"120 tooth MINI-VELO"

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Nov 17, 2012
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Broken Hill, Australia
Ok, jumping in rather late here in the hopes that the weather will co-operate in the next 3 weeks, was not going to enter but found myself inspired today by a thread and then remembered another thread that had inspired me earlier, and braved the heat outside to throw together a quick mock up to see if my vision could work, turns out it will and should not be too hard to pull off in the remaining time as long as I get a couple of days suitable for building... (Wow, that is a long sentence!)

Inspiration threads: 1: MiniVelo by Kram. (Damaged vintage turned MiniVelo): http://www.ratrodbikes.com/forum/index.php?threads/mini-velo.81016/

2: MadMax beyond Velodrome by Smoopy. (Oversize BMX turned fixie racer): http://www.ratrodbikes.com/forum/index.php?threads/mad-max-beyond-velodrome.71349

I guess you can probably see where this is heading, a set of bmx wheels attached to an oversize old racer or mountain bike frame...

A couple of options I have found so far in my stash:

1: An old 27 inch racer, with a 5 speed equipped 20 inch mountain bike wheelset, will need some geometry changes but should be an easy build. Will run front and rear derailleurs for 10 or 15 speeds, drop bars and all the good gear I can find in my old racer stash.



Option 2: An old 26" mountain bike, weld on the chainstays and dropouts off a 14mm axle equipped bmx, bend down the seatstays to meet, throw on a set of suspension forks off another mtb, and all the good gear off a freeagent bmx I have, heavy duty wheel set, bmx three piece crankset, monster stem, bars etc...

So the blue frame in this pic, the forks off the suspension mtb, and the rest from the KHS/Freeagent bmx.



My biggest hurdle in either build will be the weather followed by my health issues, this is the temp at our covered back door at the moment:


If it stays in that area they will keep the fire ban restrictions in force which will mean no welding and grinding outside, hopefully either way I go, I will only need one or two days for the frame modifications, so may be able to make it happen before the deadline...

See how I go...

In the meantime, which build do you prefer? Eventually I hope to build both, but will only (maybe) have time for one in the build-off, I am leaning towards one of them, but would be interested to know you guys and girls thoughts...

So... In the 3 hours since I posted the above, the temperature has dropped to a lovely 22 degrees (70 F), I think we finally have the cold change we were waiting on!

Forecast for tomorrow is a max of 31 (86 F) and the best news of all?


Tomorrow is normally our shopping day, but I am hoping I can convince my wife to let me play with bikes instead... :113:

So, let me know which one you prefer, pretty sure I have made up my mind now, after browsing more through my parts stash, basically one I have all the parts for, the other I would need to spend money to buy two items. Might be just enough to make the decision for me...

Yep! You guys freeze while we cook, come the big build-off though, it will be the other way around!

Small update: Got so pumped up about doing a build, I made my decision and started stripping bikes, got two bare frames to start chopping tomorrow and some forks ready to "improve" too! ;) Too dark for pics...

I'm guessing your going with option 2. Either one of them would be cool. I would probably end up building both eventually.
I'm guessing your going with option 2. Either one of them would be cool. I would probably end up building both eventually.
Option 2 is correct! Just a matter of no narrow road style tires in my stockpile for the racer one, definitely planning on building it down the track though! Love the idea of drop bars with stem friction shifters and a full gearset with tiny little 20" wheels! :grin:

Nothin' like pedalin' yer tail off and goin' nowhere... hehe a velo? I put 20's on a 27 years back when the kids were little just for a laugh, they'd be on their little bikes and I could pedal like crazy and still be right there with em', never knew it was a velo. :crazy: I like #2 best also... cool.

Ok, so plans changed a little in my dreams last night, mostly because of these two pics:



Now I want to build a full suspension MiniVelo like one of them, here is a quick mock up, I think you can see where I am headed...


Going to extend the swing arm and the seat brace back, also will jack the front forks a bit more when I redo the dropouts...

More to come...

Thanks Drac! that looks perfect for the racer one! Looking forward to building it down the track!!!

Started stripping stuff getting ready to cut and weld:


The rear triangle with the donor frame:


Decided the sun was a bit too burny, so sat in the shade stripping parts off other bikes for the build:

Weinmann DM30 Double wall 48 spoke rims with 14mm Diamond Back hubs and 13 tooth odyssey freewheel, all in great condition, barely any brake wear on the paint even!:


Almost new Tioga Comp 3's in 2.125 size:


Also got a long travel 700 lbs/inch rear spring assembly, some steel blade cranks and a few other bits and pieces ready to go, all of this stuff coming out of my bike stockpile! This is great, not costing a cent! I will probably need brake cables, maybe grips and may have to recover a seat, but that is consumables in my mind... :thumbsup:

Got a bit done this afternoon/evening, started stiching together a longer rear triangle equipped for 14mm axles, still needs more work, here is the pic for tonight as far as I got, I holding the seat in roughly the position it will end up.


I kind of like it, I think there is a cool bike in there somewhere, just not sure it is what I envisioned at the start...

While digging parts out today for building this one, I came across the perfect wheelset for the racer build, still no tires but it is gelling together in my mind nicely, I may switch over to that build while I give this one more thought.

Ok, here it is folks!

Officially changing to the racer plan, went and checked prices for 20" racer tires or slicks and was quoted between $50-$80 each!
I am all for supporting local bike shops but I can order them online for $44 a pair delivered to my door!

Decided $44 was about $50 more than I wanted to spend anyway, so decided to finally try 1HP's DIY Slick trick, however I did it slightly differently for two reasons:
Point 1, I am lazy.
Point 2, I am cheap!

So here is my method and some theory's regarding the best tires to use for making slicks.

Instead of using a belt sander (I don't have one and did not want to buy one. (see point 2.)) I used an old 5" angle grinder fitted with a flexible plastic sanding pad and 100grit sanding disc.


Instead of using a fork clamped in a vice, I just flipped a bike upside down and used it as the stand. (See point 1.)


First tire up was a slightly used and left in the sun for a year cheap semi slick, here it is half done:


Result was good, nice and fairly smooth, however it ended up very light, so I am not sure there is much rubber left over the canvas. Here is a before and after shot:


Next up was the second cheap semi slick in the photo above, however this one was barely used but had been sitting in the sun for about 4 years, found it easier to sand, and it ended up smoother than the first one, pretty sure I left more rubber on too.

The third tire was another identical semi slick however this one was brand new, never been fitted to a bike and never been outside, result was rubbish, the rubber flexed sideways when sanding ending up with lumps and bumps and even sand through to the canvas in places, stopped after doing one side:


Starting to see a pattern here, I looked for the oldest, hardest tire I had that was not cracked, I found a Kenda comp BMX style tire that looks to have been sitting in the sun for the last 10 years, hard rubber, heavy tire. Here it is halfway done:


I also discovered a better method for using the angle grinder/sanding pad combination, I would hold the wheel to stop it turning with one hand and sand each knob most of the way down, once they were all evenly down most of the way I would then used the angle/spin method 1HP uses. Here is the finished tire:


Result on this tire was the best, very smooth and even, still plenty of weight in the tire leading me to believe there is plenty of rubber left.

Here is the two tires that I have in mind for the MiniVelo Racer, the 2nd semislick for the front and the Kenda for the rear:


Here is what I looked like after sanding them down:


Here is what the forks and rim looked like:


As bad as that looks, it hoses off easily and leaves little to no residue, the clothing is a different story, I recommend a long plastic raincoat for future attempts...


My reason for picking the two tires I did is that turned out the best and seemed to retain the most weight, they also happen to be the oldest and hardest of the tires I did, I don't think that is a coincidence, I think the rubber knobs flex less as they are sanded and allow you to achieve a better result.

I also recommend finding the heaviest tires you have in your stock, these are most likely to have a thicker rubber layer left when you are finished.

Hopefully more progress soon!

I like em' when they're half done... be nice for a Nascar bike... only turns left!

Merle. :crazy:

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