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 Post subject: 20" wheels on an MTB ?
PostPosted: Sun Oct 07, 2012 8:00 pm 
Old School Grand Master
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Joined: Sun Aug 21, 2011 11:57 pm
Posts: 4074
Location: Antwerp, Belgium
We've all seen the usual 650B and 700c conversions, and some members here even have MTBs with one or more 24" wheels, but this one is new to me, so I though I'd share it.
I can imagine that something like this is a hoot to ride in city traffic.

Image

Ever since I came across this, I can't stop thinking about doing such a conversion myself.
I'd pick a better starting point than a Benz though, and I'd make sure I have enough ground clearance too.

Here's what the above bike is supposed to look like, BTW. I really understand why the owner changed the wheels.

Image


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 Post subject:
PostPosted: Sun Oct 07, 2012 8:02 pm 
Gold Trader / rb Rider / Special
Gold Trader / rb Rider / Special
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Joined: Mon Aug 31, 2009 12:26 am
Posts: 16165
Location: Rurally close.
Oh wow i love that!
Please do one so i can copy you.
Surprised thet it actually looks like it has decent clearance.


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 Post subject:
PostPosted: Sun Oct 07, 2012 8:07 pm 
Old School Grand Master
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Joined: Sun Aug 21, 2011 11:57 pm
Posts: 4074
Location: Antwerp, Belgium
cyfa2809 wrote:
Oh wow i love that!
Please do one so i can copy you.
Surprised thet it actually looks like it has decent clearance.


Heh, I just might.

I've been doing some maths, and if I can find an XC full susser that has a 14.25" BB height (center of BB axle, that is), I can drop it and still have as much clearance as my Sbikes.
14" if I switch to a 170mm crankset.

As for loving it, I know the feeling.
Those fenders look just right on that bike, and it would look horrid without those. This thing really has that Supermoto look about it.


Last edited by Raging_Bulls on Sun Oct 07, 2012 8:37 pm, edited 1 time in total.

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 Post subject:
PostPosted: Sun Oct 07, 2012 8:26 pm 
retrobike rider
retrobike rider

Joined: Mon Sep 27, 2010 12:17 am
Posts: 876
Location: At The Gates Of Dawn
What a brilliant idea and nicely carried out too. There does seem to be reasonable clearance, I wonder what sort of gearing you need to use or whether 'standard' gearing is OK.


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 Post subject:
PostPosted: Sun Oct 07, 2012 9:31 pm 
Old School Grand Master
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Joined: Sun Aug 21, 2011 11:57 pm
Posts: 4074
Location: Antwerp, Belgium
Hypothetically speaking, a 20" wheel has 0.7692307692 times the circumference of a 26" wheel (62.8" vs 81.64"). So basically the gearing will be around 25% shorter.
Sounds like a lot, but it isn't really. 42/11 on a 20" would feel like the 42/15 or 32/11 on a 26" bike.

I suspect one will be forced to run a single up front, or a double with a road cassette. Not because of the different gearing itself, but because you don't have enough ground clearance to safely run a long-cage rear mech.


Last edited by Raging_Bulls on Sun Oct 07, 2012 10:46 pm, edited 1 time in total.

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 Post subject:
PostPosted: Sun Oct 07, 2012 9:57 pm 
retrobike rider
retrobike rider

Joined: Mon Sep 27, 2010 12:17 am
Posts: 876
Location: At The Gates Of Dawn
Yeah - it's surprising how small the difference is. Perhaps run 1 or 2 x 10 and then get really radical and fit a Moonlander tyoe wheel on the front......







.....looking for my coat :oops:


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 Post subject:
PostPosted: Mon Oct 08, 2012 12:33 pm 
MacRetro rider
MacRetro rider

Joined: Fri Feb 09, 2007 4:16 pm
Posts: 8658
Check out an Airnimal Rhino
http://www.airnimal.eu/rhino.php
or a Bike Friday
http://www.bikefriday.com/bicycles/mountain
or even Sheldon Brown and his Raleigh Twenty's


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 Post subject:
PostPosted: Mon Oct 08, 2012 1:26 pm 
Retro Guru
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Joined: Tue Mar 23, 2010 11:24 am
Posts: 335
Location: Denmark
I´m at the start of a build right now, and will be building a set of 20" wheels and a set of 26" also for the bike. Just for fun...


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 Post subject:
PostPosted: Mon Oct 08, 2012 2:26 pm 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 8202
Location: New Forest, UK
Sorry, I still don't get this - why do you want a 20" wheel on it again??? :?


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 Post subject:
PostPosted: Mon Oct 08, 2012 5:27 pm 
MacRetro rider
MacRetro rider

Joined: Fri Feb 09, 2007 4:16 pm
Posts: 8658
Synthesis at the end of his last post answers your question.......Just for fun :wink:


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