Strong rear wheel suggestions needed

[knurn]

I have a 500W 48V Grubee front hub motor mounted on an old rigid Arashi Matrix mtn bike.
The rear wheel is the original Wienmann made in Switzerland.
On the rim is mounted heavy duty tube with slime and a 26 x 2.125 inch Kenda tire.

Coming back from a ride today I hit a pothole that was only 2 or 3 inches deep and I broke 6 spokes all on the sprocket cassette side.
The rim itself did not get bent probably because of the large tire.
I have 4 lead assid batteries that weight approx 50 pounds mounted on the sides of a rear rack.

I will change to a different battery chemistry when these batteries wear out but in the meanwhile what are my options for a strong rear wheel?
Should I re-lace the aluminum rim it appears fine?
Any idea of the cost for your suggested solutions. I live in Ontario, Canada.

I weigh only 130 pounds and I saw the bump so I stood up on the pedals thereby moving some of my weight to the front.

 

[northernmike]

Where in Ontario are you? There a LOTS of great local bike shops that could help you out.

What rim do you have on the front?

If the Weinmann is still OK, consider respoking it with DT Swiss stainless spokes and having it professionally trued ...

 

[JS Tyro]

If the hub motor is not too big in diameter, consider getting a better balance on the spoke stiffness on the two sides. For example, if both sides have the same spoke pattern, say 3 cross, the right side will be radially stiffer due to the flatter (less dish) shape. As a result, the spokes on that side tend to take a disproportionate amount of the load. If you have a stiffer spoke pattern on the left side and softer on the right, then more of the load will shift to the left. For example, you might try a 2 cross on the left and a 4 cross on the right. My recumbent came from the factory with 3 cross on the right and radial on the left - this is a popular mixed-pattern wheel.

If the motor is very large in diameter, requiring short spokes, you won't have many options in getting higher cross patterns.

You could also use different spokes on either side - heavier on the right.

In the above, right means right as the rider sits - the gear side; left is the non-gear side.

 

[knurn]

northernmike, I live in Cambridge, Ontario. There are a number of local bike shops here and in neighbouring Kitchener-Waterloo. The Weinmann rim appears to fine so I will consider lacing it. thanks

 

[knurn]

JS Tyro, the hub motor is on the front of my bike. The spokes that broke were on the back which has the weight from the 4 LA batteries. I mentioned that all spokes broke on the cassette side because I that this was possibly too much of a coincidence. Is it possible to just use better spokes or should I consider different patterns on each side?

 

[John in CR]

A lightweight motorcycle rim, spokes and tire mounted to your bicycle hub. They're far stronger and probably cheaper, at least they are down here. The 17" rims on mine end up a 23" diameter wheel, so you'd probably need 18" or 19" rims to get close to a 26" wheel. Just make sure you have the spacing before taking the plunge.

John

 

[Zoot Katz]

You could look at 40 spoke wheels. There aren't many options though when choosing a hub and rim.
If your wheel is running only 32 spokes you can upgrade to thirty six quite cheaply.
A popular choice for rugged service are the 13/14 ga single butted spokes but more of them is still better.
An eyeleted double or triple wall rim is most desirable.

 

[ElectricEd]

IMHO the most economical, strongest and most resilient wheel you could have would be:
1. A semi-V rim, for example http://www.velocitywheels.com/default.asp?contentID=564
Go for the Cliffhanger type if your rear wheel doesn't have much dish offset or the Synergy Rear if it has the offset amount that is typical of 8 speed and higher.
(I'm using Velocity as an example because I've just rebuilt my Crystalyte 408R using a Cliffhanger. There'll be manufacturers local to you that will have something similar).

2/ Double butted stainless steel spokes. DT make a very good 13/14/13g version.
Stainless has twice the tensile strength of mild steel and is more elastic. If you make sure that the spoke heads are seated properly in the hub flange, I'd bet that you'll not break another spoke.

4/ Lace the wheel in a cross 3 pattern. This means that the spoke length is longer than lower count cross patterns. This helps to take advantage of the elasticity component.
I have a front wheel on my Audax bike that is laced radially. It comes loose periodically which makes me think that it's just another case of if it looks too good, it probably won't work properly. Of the billions of bikes in the world, 99% are probably cross(3), which to me suggests that it is the strongest and cheapest way to build a wheel.

In the last 20 years or so of touring, off-road MTB touring and generally bashing around, I have broken plenty of Hoo-Flung-Dung stainless spokes but have never broken a DT. All my wheels have been rebuilt using DTs and have never broken a spoke afterward.

 

[vanilla ice]

Isn't the spoke angle more the thing than the number of crosses? With a big enough hub a 1 cross would be the same angle as a 4 cross on a non-motor wheel.

 

[VRdublove]

I would go with a Rhyno Lite Rim. Cheap, strong, and not too heavy. You can get them on ebay with Shimano Saint hubs already laced to them in a 3-cross pattern. I ran that on my 140 lb Etek-powered mountainbike and never had any issues.

Good luck!

 

[ElectricEd]

Isn't the spoke angle more the thing than the number of crosses? With a big enough hub a 1 cross would be the same angle as a 4 cross on a non-motor wheel.

Bang on!
Yes, you're right about larger hubs. Cross(4) on most hubs has problems because the angle of the spoke leaving the hub flange cuts across the flange, leading to rubbing and fretting that will eventually lead to a spoke breakage. It is still very tight on the current low-flange Shimano hubs. On a Crystalyte 408 with a 184 mm spoke hole diameter cross(3) and possibly cross(2) have the same problem. Cross(1) is required to have a clean path for the spoke and still have a tangential path that will minimise torque windup of the hub with regard to the rim.
Adding to that, radial spoking spoking is a no-no for a rear wheel, a motorised front wheel and especially for a front wheel with a disk brake. You can get a much greater wind up when braking due to the fact that it is possible to deccelerate with more Gs than it is possible to accelerate.

 

[Drunkskunk]

Your rim might be fine, but i would recomend a welded seam rim. if yours isn't, Velocity rims and SunRingle are both great.

The striength of a wheel rests in the spokes. good quality 14 gauge DT Swiss spokes should hold up well. the 13|14|13 are nice, but if your hub and rim aren't drilled for it, the haardly perceptable but slightly incorrect fit of the elbow and nipples can cause the spoke to be weaker than straight 14 gauge.

If you go looking for a prebuilt wheel, get one made for tandum bikes, as they are built to carry the weight of 2 riders

 

[dogman dan]

4sla's is one reason I stopped using the trike. I just couldn't keep the back wheels straight with the weight of the batts, and the cargo pounding the snot out of em. Switching to a suspension bike really helped for me, but the affordable ones have such crappy forks. But at least the crappy front suspension forks are made of motor freindly steel. I noticed the other day, a better than usual examlpe in the wallmart, a mongoose selling for under $200, that had better looking but steel front forks.

 

[JS Tyro]

The spokes that broke were on the back which has the weight from the 4 LA batteries. I mentioned that all spokes broke on the cassette side because I that this was possibly too much of a coincidence. Is it possible to just use better spokes or should I consider different patterns on each side?

The radial/3-cross I mention on my recumbent is on a rear, no-motor wheel. Yes, you can use such a pattern for the rear to balance strength regardless of whether or not there's a motor. I suggested the asymmetric spoking specifically because you mentioned the breakage on the weak side. You may have adequate strength improvement with just stronger spokes - the problem is that no one knows exactly what the required capacity is and what the best solution is. So you can try different solutions until they stop breaking.

The cheapest approach is to play with the spokes alone - fatter, better quality and/or adjust the pattern (any one, two or all three of these). You can then go to a stronger rim if you think it's necessary, but that will likely have a negligible effect on spoke breakage. If you want to go to a 40 or 48 spoke rear wheel (as with heavier touring or tandem bikes), then you're looking at changing rim, spokes and hub - the most expensive solution. If you can't make your own wheel, you'll add pretty much the same fee for wheel making regardless of which solution you choose - that can factor into how you view the net cost. Even spoke tension and proper seating of the spokes are the most critical components of wheel building in this case - you can get away with a mediocre build if the wheel is lightly loaded and you don't care about long-term alignment of the rim. That will determine how confident you are with building your own; experience counts, though a spoke tension gauge can help.

You could also go to the extreme of tied and soldered spokes - not as easy with stainless spokes due to difficulties in getting solder to adhere to stainless steel. There's a lot of debate on this, some say it only provides secondary advantages (reduced flex reduces breakage due to fatigue over a long period of time or that is supports a broken spoke so you can keep going etc), while others think it provides immediate strength and stiffness advantages.

As far as 4-cross goes: I think the main reason that 4-cross are considered obsolete is that they soften the wheel when most want the wheel stiffer and increase weight when most want lighter. At one time 4-cross was standard on touring bikes, now they all use 3-cross. It's very likely that better quality spokes generally available today more than compensate for any strength advantages that 4-cross might have; this makes 3-cross very practical. However, 4-cross can still provide a bit more flex in balancing an asymmetrically dished wheel. OTOH, mixing 4&2 vs 3&1 or 3&radial is 6 of one half dozen of another.

BTW - I don't consider 50 lb of batteries a particularly high load on the wheels. If you were 180lb ( +50) and carrying 25 lb of camping gear on the rear racks, you'd be adding something like 50 lb on the rear wheel and no one would suggest you need a monstrously heavy rear wheel.

 

[dogman dan]

If you were packing a lot of camping gear, and pedaling, how fast would you be going? I bet it wouldn't be 25 mph day in day out mile after mile. That was the problem with my trike, it sure wasn't designed to go as fast as I was going once I motorized it. Better wheels would have helped, the trike had pretty cheezy wheels for a cargo bike. The motor just accelerates the wear on bikes by a factor of about 10.

 

[JEB]

After trying different rims and tires- lots of weight on rear wheel- gocart tire cord sepration, normal bike tire tread life short, broken spokes, etc, I bit the bullet and went to a highway type trailer tire- 16" solid rim, lots of rubber, 550 or 750 lb load rating. Made a transitional steel bracket that bolted to the old wheel supports on the rear, had to spread the opening a little to insert, + brushless mars motor, #41 rollar chain, (added rear Ninga 95-96 rear disk brake, no problem stopping ).

1986 Tour easy recumbent bike.

Jeb

 

[donob08]

I wonder if there is a chance that your wheel had the spokes laced incorrectly. That is did the bulb at the end of the spoke sit down in the recess in the hub and the part of the spoke headed to the rim get bent over a sharp edge as it came out of the hub?

A friend of my got some new wheels mislaced this way and it took us a while to figure out why he was breaking spokes unexpectedly.

Spoking the wheel correctly made it a strong wheel.

 

[knurn]

donob08 the spokes appeared to been laced properly. All 6 spokes were broke on the sproket side and at the hub not the rim. I will look to insure the spoke hub ends are properly seated in the future. thanks, knurn

 

[antarctic74]

What alternatives are there to Velocity Cliffhanger rims? I'm looking for a durable rim that would be available in Europe. Unfortunately Velocity is hard to come by. Brick Lane Bikes sells them in the U.K. but they don't have Cliffhanger in the catalog. If you know other rims that might be well suited for a BMC V2T in 700c size, please reply.