Separate names with a comma.
Discussion in 'Motorized Bicycle General Discussion' started by Patr1ck, May 25, 2010.
Which do you like better? Please vote and then tell me why you voted that way.
Aluminium frames are made of very thin walled tubing that have potential to crack if receiving a crush point from excessive calmping force from U-bolts.
My bicycle frame is aluminium and i've modified the U'bolts that came with the SickBikeParts shift kit to spread the load over a wide area, avoiding the possibilty of point load pinch force, but the same principle aplies to the standard Chinese engine kits.
These photos show the end result of my next door neighbours attempt to fit an engine kit to his aluminium framed bike.
I gave strong words to be exceptionally careful when fastening the clamps, making him fully aware of how thin large diameter aluminium frame tubes happen to be.
Needless to say, he crushed and split the frame tubes of his bicycle.
A steel frame is my personal preference, even though my bike has an aluminium frame for reasons outlined below.
The problem though with a steel framed bicycle is that they are placed in the lowest price category, so you can't get a steel framed bicycle with mounting lugs for I.S. brake calipers and disks.
I honestly think it's six of one & 1/2 a dozen of the other lol - it's all about application *shrug*
If ya want simplicity of build and easy of modification - it's defo the steel. If you want absolutely every last bit of performance out of these engines - it's gotta be the aluminum.
Every ounce counts, but it's true aluminum needs a touch more attention paid to construction techniques
In my opinion, Chromoly is the only way to go. It's thin, light and way stronger then Aluminum or the cheap steel frames. It can be found in alot of your mid 90's decent bikes. You can usually pick them up on craigslist for $50-$75.
I should have been more clear in what i was saying; should have listed Chrome Moly frames as my personal preference, but carelessly didn't seperate chrome moly frames from mild steel frames in my opinion - my fault.
Well... the poll does only specify aluminum or steel lol, there is a coupla of other unmentioned options but I'm assuming that's all Patr1ck wanted
I wants me an unobtainium frame w/buckyball bearings o.o
I went with Aluminum - for the sole reason that it is all I have any experience with So far it is working great! (Well the frame is at least - having minor problems here and there with other engine related things)
I like aluminum; its lighter - maybe more vulnerable, but its still lighter. Honestly, I really don't care. Before motorbiking, it was (and still is) mountain biking, and before that it was BMXing. Aluminum has always been better (especially mountain biking).
Chromoly for sure. I built a mountain bike and the tube diameters fit the stock engine mounts perfectly without using special clamps. Also it is stronger. One of the best advantages is it absorbs vibrations much more than aluminum. When I ride my non motorized mountain bike in the mountains aluminum is the best. My single speed mountain bike weighs just under 20 lbs which is great when climbing 3000 ft in one ride with my legs as the power source. I don't think the extra weight makes any noticable diference with a motorized bike.
I prefer steel because I like customization, steel is all I can work on so it gets my vote.
Chromoly, hmmm. I didnt know they made frames out of that stuff. Do cruisers come in that?
My favorite bike is an old non triple triangle GT MTB, its cro-moly.
My 70's Speedwell is only High Tensile, but its quality frame with brazed lugs.
Cro-moly bikes are out there, a few tips for identifying them.
Look for an Old Shcool name brand, like GT, Mongoose, Diamond Back or older high end Huffy or Schwinn. It will have quality alloy cycle parts and a three piece crank.
It needs to be from the '80's or early '90's.
It will have 1.125" or so tube sizes.
When tapped with a screwdriver or such it will ring like crystal.
A mild steel bike with thud like glass.
The ride of a nice CroMoly bike is a feeling of stiffness and control compared to the muddy, flexing and twisting feeling of uncertantity with a bike made from gas pipe.
There are nice steel bikes around, but not made in recent times.
Forgot to mention that CroMoly bikes are still available new
Theres probably others.
Hipsters, fixie and bike courier types swear by them.
I like the old ones.
Wildemere, My mb is a GT tripple triangle as well. It is a perfect fit with the engine kit. Not only is it chromoly but the design of the frame is awesome!
My GT is non-triple triangle, one of the earlier designs from 1990 or so. Its an Outpost. Apparently quite rare these days.
Here is a pic. Its a bit ratty, but its reliable and rides nice.
Your frame looks very similar to mine. Lets call it the double triangle! I had my frame powdercoated black. It came out looking great.
I have a big question for you, when you get up to speed does your front end start to wiggle real fast? I also put a suspension fork on mine and have determined that it is the fork causing the problem. The fork is adjustable and the softer the setting the easier it wiggles and the harder it is set the less it wiggles. It is actually scary when it happens. I have been wondering if others with mountain bikes and a suspension fork have the same problem. You are a perfect person to ask since our setups are similar.
No wiggles or wobbles here, try these tips-
The adjustment is just spring or damping related, probably preload. It has only a small effect on steering geometry which is your likely problem. Not enough trail in the steering, causing "tank slappers"
First check the headset for loose, tight, pitted or worn bearings- most common cause. Is the steering action smooth?
Then the front wheel:- check for rim runout and bearing play, run max air pressure on a slick tyre to eliminate a possible cause, a low pressure knobby on pavement could cause cause a wobble.
Get the seat lower and the bars higher, this will improve your center of gravity and put more weight on the rear end.
If the above checks don't eliminate the problem then its time to start measuring the frame alignment and frontend geometry.
I think you don't have enough trail, (blue line) but its hard to tell by the pic.
More trail is slower steering, less is faster.
Bicycle Steering Geometry
Bicycle and motorcycle geometry - Wikipedia, the free encyclopedia
Thanks for the ideas, I will look into all of those. And yes you are correct when you say tank slapper. That is exactly what is hapening.
Aluminum is great for Lance Armstrong but as mentioned above it doesn't seem to be stout enough for a powered application. You're adding a 20 lb. motor any way so another few pounds of steel isn't going to affect the overall weight of your steed. Cromoly IS steel; just better than ordinary steel.
Lance and his cronies wouldn't spit on aluminium frames, too much energy is lost in the frame flex. Carbon fibre with hollow titanium parts and ceramic bearings is what the racers use. Even crank arms are CF these days. Seen thier wheels? Then their new electronic shifters... Their bikes cost $20,000+ each. They use four or five of them in a long race
Plain, non heat treated aluminium is not good for bike frames, downhill and hard core BMX racers prefer Chromoly or Titanium as aluminium alloy is too soft and it cracks/breaks without much warning.
For Motorized bikes the order of preference for me is:-
Titanium:- Highest strength to weight ratio of any metal, would love to have one!
Chrome Molybdenum Steel:- Used in the high end bikes, famed for its ride quality. Accurate steering and feel.
High Tensile Steel:- Mid level bikes, some cruisers, better than mild steel, rides nicely with a good feel.
Mild or plain steel: Supermarket and kiddie bikes, fairly flexible, rarely fails. poor, uncertian ride quality.
Aluminiun:- These days its mostly a gimmick, at the supermarket level anyway. A good name brand heat treated alloy frame is another thing but but still prone to random failure compared to the other types. More flexible than a good ChroMoly frame
Carbon:- Would be awesome except for the clamping problems and if scratched/scored wil fail in that area.
For motorised applications i think steel is the go. The better the steel the better the ride. Most aluminium frames have too much flex and a poor breaking/failure mode for heavy duty use.
My aluminium shifter bike has signifigant flex in the BB area under full power. Previous steel shifter bikes I built did not have this issue.
I wish for a Titanium frame one day.