Anyone run 20" wheels on a DH bike?

[John in CR]

The DH bike I picked up is great for the trails, but for my normal ebiking it's like rents in NYC and just "too damn high". I realize that I'll need some shorter cranks, and the smaller wheels won't go over obstacles as easily as the big wheels, but is there any reason not to try some 20" wheels other than it might look odd?

Benefits in addition to being able to put my feet on the ground:
More than 3" of extra clearance up front would open up a whole new world of battery space under the downtube.
Extra space on the swingarm would make fitting an RC drive that must simpler.
A lower CG will make going fast more comfortable on this wheelbase.

Here's what it looks like now:


and this is what it would look like with 20" wheels...not as bad as I thought it might. It's like one of those little folding commuters, but with 7" of suspension travel and more wheelbase I believe it would ride quite a bit better.

 

[Kaño]

I like the supermotard look, with those 20 inch wheels. :wink:

 

[Ypedal]

I got 3 bikes with 24" front and 20" rear.. one of wich is my Norco Chaos.. ass on the seat, both feet flat on the ground, cranks work, sitting upright ( not leaning forward ) .. Love it !

 

[dbaker]

I have a Giant Faith with 17" moped rear and 26" front. I have an Haro/Intense with a 16" moped rear and 24" front.

 

[RWP]

I tried 20" rims with hookworms on my RM7 but I thought it looked really dorky.

But maybe with wide rims and these tires:
Pirelli ML 75 Rear Moped Tire
http://www.motorcycle-superstore.com/5/32/404/5780/ITEM/Pirelli-ML-75-Rear-Moped-Tire.aspx
Pirelli ML 75 Front Moped Tire
http://www.motorcycle-superstore.com/5/32/404/5785/ITEM/Pirelli-ML-75-Front-Moped-Tire.aspx
it would look better?

I think these tires and rim options are covered eleswhere on ES.

Edit:
"I think16" moped tires = 20" bicycle rims."

Maybe these rims:
Sun Ringle Big City
http://www.chainreactioncycles.com/Models.aspx?ModelID=20495

 

[John in CR]

On my main bike I run a 14" motorcycle tire on a couple of my hubbies. One is almost a 20" diameter and the other 19", and for the fronts I run a 24 on one and a 20 on the other. If I can fab a bolt on dropout adapter to extend the wheelbase by a 3 or 4 inches, then I'll run one of my big hubbies and the CG might be forward enough to run a 24" front. Otherwise I'll have to run a 20 on the front to help keep the wheel on the ground.

The alternative is dual hubbies and the extra front weight will be welcome.

 

[Jeremy Harris]

How about just changing the rear shock for a shorter one and leaving the wheels as they are? My guess is that you could lower the rear a couple of inches without having a major effect on the head angle.

Jeremy

 

[dogman dan]

Since we already know you would be doing about zero pedaling, I can't see any reason not to do it. On nasty trails the pedals would be a problem or trying to pedal through a corner. But as long as you rode with both pedals halfway, instead of one up one down, I can't see any problems at all.

 

[John in CR]

Since we already know you would be doing about zero pedaling, I can't see any reason not to do it. On nasty trails the pedals would be a problem or trying to pedal through a corner. But as long as you rode with both pedals halfway, instead of one up one down, I can't see any problems at all.

Didn't you hear that I'm converting to electric assist instead of pedal assist? Ooops sorry, that wouldn't be funny even on Apr 1st. 8)

I never bothered to shorten my cranks on my main bike, and they're so low to the ground I could lock them I could use them as an either side kickstand, so I'm quite used to riding with cranks parallel to the ground and avoiding pedal strikes. I shortened the cranks a lot on my little race bike prototype and the shorter cranks are much more comfortable for no pedaling riding with the cranks parallel.

This won't be a hill bombing bike, because I really want 2wd for that, and to start with a cheapie steel frame that I can trash but be able to repair while I'm learning that kind of riding. This bike will be more like a Lexus SUV, ie a comfort sport cruiser that may be capable of some off roading but not really meant for it and definitely not used for anything serious.

John

 

[Thud]

who cares what it looks like......if it works it works.
here is my Marin mocked up with cheap 29er forks.

The smaller wheels should be fine..you may increase trail by a millimeter or two.

 

[Doctorbass]

I will attempt 20" wheel on my DH comp soon.

Now i'm converting my Mongoose ( previously equiped with 20 rear and 26 front) and will be 20 rear and 20 front..

BUT it' s not really 20'... i'm using the XERO MX electric motorcycle rim that Ypedal sold me ( they are for 20" wheel but are wider ... 40mm width) and I installed 16" x 3.00 motocross tire on them

IT LOOK SO NICE !!!

They outherdiameter of the tire is 22.5" wich i find it a very great trade off !!! bigger than 20" bicycle wheel and smaller than the 24"... JUST PERFECT !!

I will use it to commute between home to my work. in the SNOW !!.. These tires are KENDA and DURO tires

you can see 16" motocross vs 20" bicycle here:

The motocross tire in the 20" wheel bicycle Zero MX rim:

My thread:
http://endless-sphere.com/forums/viewtopic.php?f=3&t=23933&p=347680&hilit=20+tire#p347680


BTW.. FOR THOSE WHO ARE INTERESTED IN THESE ZERO MX RIM... YPEDAL HAVE A GREAT DEAL ON THEM !! HE HAVE more than 30 still availlable!!.. EXCELLENT OPTIOJ AND VERY STRONG !!! EXCELLENT PRICE TOO !!!

Doc

 

[John in CR]

It seems like I'm not the only one who thinks these DH bikes are just "too damn high", so I'm in good company. Now I just have to hope I don't hit an obstacle that ends up being more like a wall to a 20", but a 26" or 29" would have rolled right over.

 

[dogman dan]

It does look nice Doc! And you avoid the problem I have with my blackcomb. I just barely fit the tire of my 26x 2.5 knobbies on the rear on my dirt/ sand bike. Had to grind a bit of the kickstand mount off to do it at all. But the obstacles I'm riding over, I still want the 26" rim.

With smaller rims, you can go fat. 8)