Wide tyres and rims?

_Chris_

_Chris_

100 W
Joined
Aug 21, 2012
Messages
151
Location
Australia
I have been researching How I will make my bike and noticed some guys use these wider tyres and rims on the rear hub motor. Does anyone know where to get them and if there is an advantage over a normal 26" one? Why choose a smaller diameter wide rim?
http://www.youtube.com/watch?v=z2YhUHMdY2M&feature=related

thanks in advance.
 
More contact area and larger footprint, hence more traction, higher cornering speeds. Wide for me rides smoother, absorbs road shocks better, and provides greater floatation in the event that I am forced off the pavement at speed into the softer shoulder consisting of dirt, sand, gravel, mud, or a combination thereof. A smaller diameter tire/wheel on the rear would give one quicker acceleration out of the hole, more hill climbing ability, and improved handling for certain types of riding styles. Lots of motorcycles have fat rear tires. 8)
 
+1 for the Maxxis Hookworm on the broken wheel. I have them on both ends. I run a 8fun BPM code 13 at low power (20-24 mph). For me these tires are comfortable and have resisted the flats my high end, but light, MTB tires got from even tiny thorns. My guess is the fellow in the video will stick with his choice of a Hookworm on the rear tire. It is pretty amazing the tube and tire survived the impact that destroyed the rear wheel. You do need to be sure your frame has enough clearance for these 2.5 inch wide tires.

From what I've gathered, the old Hookworms are two ply and tougher than the newer ones. Some one please chime in on this point and if I'm correct tell us how to tell the difference.
 
If you have a disc brake in the back, it is no problem at all to switch between rim sizes. The effects (good or bad) of switching to a smaller rear rim and smaller diameter rear tire include the following:

Lower bottom bracket height
Slightly lower center of mass
Slightly slacker frame angles
Change in steering trail (depends on specific before & after angles and wheel diameters)
Stronger wheel, all else equal
Higher rolling resistance, all else equal
Degradation in ride quality, all else equal
Lower unsprung weight, all else equal
Reduction in gyroscopic force
Reduction in moment of inertia (less energy to spin up)
Increase in thrust for any given motor torque
Reduction in road speed at motor free speed

But one of the reasons that does not fall under "all else equal" is the fact that you can usually fit a fatter rim and tire if you drop to a smaller rim diameter, without fouling the frame. In some cases, you can substitute a rim a couple of inches smaller, but have the inflated diameter of the fatter tire be about equal to what it was before. This characteristic has been used in the hot-rod styled cruiser bike sector, where some manufacturers have substituted 24x3.0" tires for the 26x 2.125" tires that were standard on cruisers.

In the e-bike world, smaller rims are put on hub motors most often for the purpose of reducing the overall diameter of the wheel, to help the motor attain a more efficient RPM for high performance.

Chalo
 
Not all frames can take the tall wide rim/tire so measure to be sure. They can be too tall and tire can hit the front forks or rear frame. Tires can be too wide and cause problems front or rear as well. I have a 26 inch Hookworm up front, on the pic, it is actually 27 inches high and things are a bit tight. Went with a 24 inch in the rear actual height 25 inches. Still room for a real fender here. Google is your friend for wide mtb rims. Weinmann makes some 1.75 inch rims that are acceptable and not overly wide in both 24 and 26 inch heights. You see them in the pic although I had them powder coated yellow, black or silver are stock colors.

davesbike1.png
 
What I am thinking is after you guys filled me in with info is that most bought frames are not really thebest for eBike frames. I might get access to a pipe bender some pipe, a qelder and chop up an existing frame and make a decent one. I am just not liking normal bikes. If I do that then the fittingrestrictions are reduced.
 
I likes phatties, and have the Hookworms on the 26" front and the 24" rear: Arguably - one of the best setups for bicycle wheels.

If I had to do it over though, I'd go with DOT-rated moped tires for toughness. Overkill if yer just doing dirt riding, although wiser for cross-country-road.

Grippy in the wet wet urban wilderness, KF
 
recompence may still have some 20"x47mm rims,,,32 spoke,aluminum double wall that he had made for him... $45.00..nice rim..i have one on the rear running nuvinci with 1200watt cyclone :mrgreen:
 
The fingers said:
If the tire is too wide on mine, the brake hardware hits the tire sidewall preventing the pads fron reaching the rim. :(
Click to expand...

That suggests either a switch to a wider rim, or a switch to traditional cantilever brakes. Brakes like these can be made to swallow whatever tire you like:

georgia_gould_orbea_lobular_brake_front_600.jpg


Chalo
 
Chalo said:
If you have a disc brake in the back, it is no problem at all to switch between rim sizes. The effects (good or bad) of switching to a smaller rear rim and smaller diameter rear tire include the following:

Lower bottom bracket height
Slightly lower center of mass
Slightly slacker frame angles
Change in steering trail (depends on specific before & after angles and wheel diameters)
Stronger wheel, all else equal
Higher rolling resistance, all else equal
Degradation in ride quality, all else equal
Lower unsprung weight, all else equal
Reduction in gyroscopic force
Reduction in moment of inertia (less energy to spin up)
Increase in thrust for any given motor torque
Reduction in road speed at motor free speed

But one of the reasons that does not fall under "all else equal" is the fact that you can usually fit a fatter rim and tire if you drop to a smaller rim diameter, without fouling the frame. In some cases, you can substitute a rim a couple of inches smaller, but have the inflated diameter of the fatter tire be about equal to what it was before. This characteristic has been used in the hot-rod styled cruiser bike sector, where some manufacturers have substituted 24x3.0" tires for the 26x 2.125" tires that were standard on cruisers.

In the e-bike world, smaller rims are put on hub motors most often for the purpose of reducing the overall diameter of the wheel, to help the motor attain a more efficient RPM for high performance.

Chalo
Click to expand...
I think the smaller rim idea is good. where do you start to buys stuff? do you buy the bike first or the motor rims and wheels then fit frame to that? I am favoring the 9c motors so far
 
do you buy the bike first, or the motor rims and wheels then fit frame to that?
Click to expand...

It depends on whats the most important to you and also...what your E-bike budget can afford. The Surly "Large Marge" is a super-wide rim, available in 24-inch and 26-inch diameters, in a 65mm width, rim is $120+, and yes the only tires that will fit are expensive. http://surlybikes.com/parts/large_marge

As mentioned, the wider 20-inch (OD) bicycle rims can accept some of the narrower16-inch (ID) Moped tires, the 3-inch moped tires are fairly affordable, but may not fit in all forks/frame-rears. The 16-inch moped tires are approximately 24-inches in outside-diameter (OD). http://endless-sphere.com/forums/viewtopic.php?f=3&t=40123
 
spinningmagnets said:
do you buy the bike first, or the motor rims and wheels then fit frame to that?
Click to expand...

It depends on whats the most important to you and also...what your E-bike budget can afford. The Surly "Large Marge" is a super-wide rim, available in 24-inch and 26-inch diameters, in a 65mm width, rim is $120+, and yes the only titres that will fit are expensive. http://surlybikes.com/parts/large_marge

As mentioned, the wider 20-inch (OD) bicycle rims can accept some of the narrower16-inch (ID) Moped tires, the 3-inch moped tires are fairly affordable, but may not fit in all forks/frame-rears. The 16-inch moped tires are approximately 24-inches in outside-diameter (OD). http://endless-sphere.com/forums/viewtopic.php?f=3&t=40123
Click to expand...
every time I make one it costs me over $2000. I am resigned to expensive.
 
Where are you at Chris? In the USA our resident rim and hubmotor wheel building expert is at Holmes Hobby. JRH has lots of experience with wheelbuilding, and provides a first class hubmotor service.

Depending on the limitations of your frame, he can suggest a bike rim or a moped rim and tire.
 
dogman said:
Where are you at Chris? In the USA our resident rim and hubmotor wheel building expert is at Holmes Hobby. JRH has lots of experience with wheelbuilding, and provides a first class hubmotor service.

Depending on the limitations of your frame, he can suggest a bike rim or a moped rim and tire.
Click to expand...
I am in Australia and its hard to get info here. Bike shops dont want to know unless it involves a quick sale of standard bikes.
 
http://www.choppersus.com/store/ is a good place to get extra wide rims, tires, and unusual parts. JRH is a great place for Spokes and may have other leads on rims.

And if you can build your own frame, Go for it! You can solve the battery placement problems and torque arm issues as well as build in clearance for extra wide tires. I'm working on a Fat tir Custom frame my self at the moment.
 
Hyena might have better info for you on AU sources for stuff. Or be able to supply it. Might give him a shout. http://www.hyenaelectricbikes.com/
 
Thanks dogman I will do that.
 
jateureka said:
For Aussies, you might want to have a look here http://www.jubecustoms.com.au/shop/17/Street-Cruiser/2/STREET-CRUISER-by-JiM-JunkEe
For $799 cruiser with 24 x 4.25 tyre on double wall 36H rear rim and disc brakes, I'm going to have to find time to visit their shop and check it out... 8)

They had just the rear wheel for sale here also http://www.gumtree.com.au/s-ad/alde...25-tyre-and-100mm-rim-jube-customs/1004100075
Click to expand...
I just chatted to the guy that sells them and am interested in the tyre and rim. I told him he might want to post here they are available and everyone can access them. one more question is a low pressure tyre ok for hub motors? That one is 35-40 psi.
 
_Chris_ said:
I just chatted to the guy that sells them and am interested in the tyre and rim. I told him he might want to post here they are available and everyone can access them. one more question is a low pressure tyre ok for hub motors? That one is 35-40 psi.
Click to expand...

Why wouldn't low pressure be OK for hub motors? You get better traction and better shock absorption. The only tradeoff is higher rolling resistance on smooth surfaces.

But in a 4.25" tire, 40 psi is not low pressure. That's a huge tire, and its perceived hardness at 40psi will be equivalent to about 80 psi in a mountain bike sized tire. I'd try it at 25psi and go up or down from there according to the ride quality you are after.

Chalo
 
Chalo said:
_Chris_ said:
I just chatted to the guy that sells them and am interested in the tyre and rim. I told him he might want to post here they are available and everyone can access them. one more question is a low pressure tyre ok for hub motors? That one is 35-40 psi.
Click to expand...

Why wouldn't low pressure be OK for hub motors? You get better traction and better shock absorption. The only tradeoff is higher rolling resistance on smooth surfaces.

But in a 4.25" tire, 40 psi is not low pressure. That's a huge tire, and its perceived hardness at 40psi will be equivalent to about 80 psi in a mountain bike sized tire. I'd try it at 25psi and go up or down from there according to the ride quality you are after.

Chalo
Click to expand...

Excellent point about big tires. The 5" wide scooter tires on a couple of my hubbies are hard at the recommended 32psi. They don't fee right at lower pressure though. My big fat Kenda Flames are an exception. They're recommended for 40psi, but they have too soft sidewalls and a high profile, which combine to feeling unsafe at lower pressure. In turns they feel like they want to just roll off the rim in turns at lower pressures. I don't even like how much they give laterally even at 40psi. They're cool looking comfort cruisers as long as you don't get aggressive though.

John
 
Ideally, the inside width of the rim should be half as wide as the tire, or wider. You can get away with a lot less rim width, but then you have to use more pressure to stabilize the tire.

My mountain bike has tires about 75mm wide, and rims about 38mm wide inside the bead hooks. I can use pressures down to about 15psi before things start to feel squirrelly. On another bike, I have a 38mm tire mounted on a rim 13mm inside width. That tire tries to roll off at pressures below about 60psi, well above the minimum rated pressure.

Chalo
 
Just one itsy bitsy, prolly irrelevant point at this stage, Centrepull style Cantilever brakes as mentioned by Chalo are not a good idea on front suspension forks...

braking=compression of forks = loosening of brakes...

Experience has taught me so.

Joe
 
winkinatcha said:
Just one itsy bitsy, prolly irrelevant point at this stage, Centrepull style Cantilever brakes as mentioned by Chalo are not a good idea on front suspension forks...

braking=compression of forks = loosening of brakes...
Click to expand...

You have to hang the housing stop from the same structure as the brakes. The original bicycle suspension forks incorporated this feature, but after the rise of linear pull brakes in the late '90s, forks stopped coming with it.

RockShoxMag21Fade.jpg


You can still buy an add-on housing hanger for forks that have a mounting hole in the arch:

14521.jpg


It's not a bad idea to use a stop like this even on a bike with a rigid fork, since it keeps fork flex from feeding back into the braking and causing shudder. Better yet is to use linear pull brakes-- but not all brake levers work with linear pulls, and all of them work with traditional cantilevers.

Chalo
 
You must log in or register to reply here.

Similar threads

E
Any experience with the QS 17x4.5 12-14KW liquid cooled hub motor?
Replies
15
Views
734
Dui ni shuo de dui
Dui ni shuo de dui
E
How should ebike wheel design change?
Replies
13
Views
1,277
calab
C
K
Hub successfully rebuilt! need advice for cutting and welding larger seat and chain stays on rear triangle
Replies
14
Views
734
nicobie
nicobie
M
    • Like
1,500 lb eTrike???
2 3
Replies
66
Views
2,132
Diggs
D
C
Optimizing DD motor and moped rim for 60km/h and 2.5kW (and other questions)
Replies
5
Views
946
chadez
C
Back
Top