Strengenthing my new cruiser

Discussion in 'Motorized Cruiser Bicycles' started by Greenlake, Aug 18, 2010.

  1. Greenlake

    Greenlake New Member

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    Hi there.

    New to this forum and motorized bicycling.

    Just bought a Huffy beach cruiser from walmart (see pic below) and ordered a 49cc 4 stroke 4g t belt engine kit.

    Wondering if any of you have any advice to whether I need to strengthen my bike in anyway to handle the motor?

    It has a steel frame and steel wheels.

    The gentleman I ordered the engine kit from said he has the same exact set up on his bike and has never had a problem....but just wanted to make sure with you guys.

    I don't plan to ride this everyday. I live in Seattle, unfortunately, the weather doesn't allow it :/
    But I would like to once a week....just go putt around town and do an errand or two.

    Also, it only has one brake in the rear. Does anyone recommend an easy front brake set up...like a disc, drum, U shape etc....

    I would like to keep it as ol school looking as possible so a disc brake setup would probably be my least favorite.

    Any help would be greatly appreciated...

    <a href="http://s132.photobucket.com/albums/q18/JGerlitz/?action=view&current=SAM_0239.jpg" target="_blank"><img src="http://i132.photobucket.com/albums/q18/JGerlitz/SAM_0239.jpg" border="0" alt="Photobucket"></a>
     
  2. biken stins

    biken stins New Member

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    Welcome to the site.
    Would get some better tires and tubes. Grease everything real good.
    As a front brake goes I like the Husky bicycle one but they cost almost as much as your bike with the shipping added.
     
  3. Chalo

    Chalo New Member

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    The frame will probably not be a problem. The rear dropouts (frame ends where the wheel attaches) might be flimsy. Nothing to do there but try it out and see if it holds up.

    The wheels will have reliability issues if you ride other than gently, slowly, and infrequently. If they get too beat up to tolerate, do not replace them with the same. Replace them as necessary with wheels that have aluminum rims (preferably double walled) and stainless steel spokes. Have a qualified shop condition them for heavy duty use. Do this before the rag joint sprocket is attached if they are snobs about motorized bikes.

    It might be that he does not have a problem, it might be that he does not acknowledge problems when he detects them (very common), and he might just be oblivious (also very common). The assessment of a typical MB owner as to whether his bike is in good running condition is in my observation very untrustworthy.

    The strongest braking you can get on that bike without spending a pile of money and/or modifying the bike is a linear pull brake (V-brake) on an adapter plate like this:
    [​IMG]

    The plate mounts on the bike's fork, and the brake bolts up to the plate. You could also replace the bike's fork with one that has studs, but that would probably cost more before everything was ready to ride.

    The minimum safe braking to use on your bike is a good quality front caliper brake with good pads. Any rim brake is going to be crippled by a steel rim. Brake pad friction is poor on dry steel rims and almost nonexistent on wet steel rims. This is one of the primary reasons to use aluminum rims.

    That's OK, because you can't just put discs on a bike like yours that isn't equipped for them. At the least, you'd have to weld on a mounting tab for the caliper and switch to a disc compatible wheel.

    To be frank, I'm not clear why people so often choose a coaster brake cruiser for a motorized bicycle conversion. Those bikes are heavy, weak for how heavy they are, complicated to mount things on, and crowded inside the front triangle. They usually lack hardpoints for racks and accessories. They limit the choice of drivetrain options. They usually don't come with decent rim brakes (or any at all), and then the typical MB kit makes it likely that the builder will mess up the coaster brake.

    Much, much better would be an old pre-suspension mountain bike like this one:
    [​IMG]

    That frame has strong, modest diameter straight round tubing, lots of space inside the frame, lots of space between the rear wheel and seat tube, capable brakes, wide range gearing, and plenty of braze-ons and bosses to mount things upon. Good solid used examples of this sort of bike are not even expensive.

    But I guess because Whizzer used a goofy heavy cruiser as the platform for their motor kit sixty years ago, that's what everybody feels like they have to use now? I don't get it. Whizzer didn't have very many suitable bikes to choose from. We do. Why don't y'all use them?

    Chalo
     
  4. Kevlarr

    Kevlarr New Member

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    Your bike should be fine just keep an eye on the seat stays, those are a definite weak point on huffy cruisers.

    No need to spend a bunch on brakes, just get a set of caliper brakes and mount them up if you feel you need some extra stopping power.

    V or cantilever brakes are nice but I just can't see justifying the expense of buying those adapter plates, for the price of a pair of those you could have gone with a cruiser with those brakes on it already.

    Be sure to go through and grease the wheel bearings and go through the coaster brake. Make sure everything is well greased and properly tightened. There are quite a few here that have thousands of miles on those wheels so don't worry about that.

    Not everyone likes MTBs, some love the look and ride of a cruiser. Saying that A MTB is the best platform for a motorized bike is like saying dirtbike is the best choice for a motorcycle.
     
  5. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Ummmm....OK!?!
    [​IMG]
    [​IMG]

    I think?lafflaff
     
  6. Chalo

    Chalo New Member

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    I've seen the hokey finagling that folks use to mount motors on fat, oval, or tapered tubing. Sometimes it works, sometimes it doesn't, but it's not cool.

    The forks on those two cruisers came from mountain bikes. Thus they accommodate strong rim and hub brakes. But for the price of a new Surly fork and a disc brake setup to upgrade a Wal-cruiser, you could buy a complete old MTB, get good brakes included, and have an easier time setting up the motor mounts, racks, fenders, etc. And it would be stronger and lighter than a cruiser.

    Not every cruiser is unsuitable for an MB conversion, just like there are a lot of mountain bikes that aren't cut out for being MBs. But most of the junky cantilever frame bikes that people pick as platforms for their motor kits are problematic and crude.

    Chalo
     
  7. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Let's just say there are less mountain bikes suitable for motorizing than cruiser style bikes....does that sound right? Let's also say you are in the Cruiser forum bad mouthing cruisers....would that be correct?
    This is not my thread, nor yours, so be respectful to the original poster of this thread and start your own. And just so you know, black 4-stroke $550 all brand new....blue 2-stroke $250 all brand new and both bikes are lighter and stronger than MOST! $20 used Surley forks on both....so bahhh.brnot
     
  8. Chalo

    Chalo New Member

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    2010 models? Probably true. But just about any pre-1992 MTB will be a categorically better candidate for conversion than a curved-tube cruiser.

    By the same token, an old straight tube cruiser like a Univega Rover would be great, except for the lame brakes, and as long as the frame has headroom for the motor.

    As for today's options, a Surly 1x1, Redline Monocog, or SE Stout would do the job reliably and economically. But they'd be no better than a twenty-year-old MTB and would cost more.

    If you say so. I'm not here saying, "kwoozas suk", though; I'm telling you why cantilever frame cruisers have significant shortcomings compared to rigid MTBs, city bikes, and even road bikes when it comes to mounting things on the frames. Or braking. Or moving under pedal power.

    Both those bikes are superior to the average cruiser in at least one regard. Neither one has a second top tube or cantilever stays to crowd the front triangle. And the black one has a straight down tube, which is better both structurally and for motor mounting than a curved tube-- but is not characteristic of cruisers in general. So assuming you were going to pick bent-tube bikes for your MB conversions, you picked a couple of good ones.

    Yet you swapped the forks of both of them for mountain bike units. Why? Because stock cruiser forks are inadequate for the job! They don't provide mountings for brakes that are strong enough to be safe at motorized speeds. That's a fixable problem, for sure-- but when another bike comes equipped that way to begin with, why choose the weaker, heavier, more difficult option and then have to swap the fork?

    Chalo
     
  9. Kevlarr

    Kevlarr New Member

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    Lets just all toss out our cruisers and get mountain bikes to put our motors on because we're obviously doing things wrong.
    :rolleyes:

    Dude, think about what you're doing. You are in the CRUISER forum posting in a thread titled "Strengthening my new cruiser" telling the person to get a mountain bike. Why not go over to a roadster forum and tell them that roadsters are weak for how heavy they are, complicated to mount things on, are crowded inside for passengers and have no place to store luggage then tell them to all get muscle cars because they have stronger frames, better brakes, a back seat and a big trunk.

    You've made your point, you like MTBs over cruisers, good for you.
     
  10. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Since you insist on jacking this guys thread....I'll jump right back in...sorry Greenlake...
    OK, your talking to an older guy (me) who raced Mountain Bikes for over ten years on the NORBA circuit ( over ten years )...teach me about the wonders of an MTB that I don't already know...pahleeease. Now then, both of my personal current builds are as you see, cheap Chinese aluminum framed cruisers, they're not superior to anything except your thinking. The black one cost $150 shipped, the blue one $119 from Toys-R-Us.....superior? The forks that came on both were as strong and beefy, not too mention as light as any non-suspended mtn. bike on the planet. Gee sorry, no they didn't have disc brake tabs welded on them...I like disc brakes.

    Both of those bikes are as light and strong as any mountain bike you will ever build for the money. Yeah, maybe I got lucky with two cruiser builds that went together with nary a hitch....oh lucky me! So what is your point?????????? Let me guess.....bashing cruisers. I'm done here.
     
  11. Kevlarr

    Kevlarr New Member

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  12. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Isn't that like cheating Kev? Who would dare put superior MTB parts on a cruiser.... and think of the cost???lafflafflaff
     
  13. Dave31

    Dave31 Moderator
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    Everyone has different taste, styles and preferences. Some like cruiser, some like Mt. Bikes, some like only vintage and board track style. Some only put $300 into there builds, some spend thousands.

    We are all individuals and will build and ride what we want and like. To knock someone down for that is not cool.
     
    #13 Dave31, Aug 21, 2010
    Last edited: Aug 24, 2010
  14. Chalo

    Chalo New Member

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    I've been working intermittently as a bicycle mechanic since 1992, working as a machinist and prototypist almost that long, and building bike frames from tubing and bike parts from billet most of that time. My last job was over five years as a machinist and technician with a private space flight program in Seattle (where Greenlake is). You might know a great deal about riding MTBs, but you have said nothing so far that indicates any particular understanding of the mechanical principles at work.

    A bicycle frame is a truss. Trusses do not use curved components-- that would defeat the purpose of a truss, which is to eliminate bending loads and substitute tension and compression loads. To get back the strength lost by making a truss out of curved pieces, you have to make it substantially heavier. Or you can choose to let it be substantially weaker instead. Neither choice especially befits a motorized bike, even if that was the most practical choice available to Whizzer back in the Iron Age.

    They are superior to frames that have double top tubes or cantilever stays, if your aim is to mount a motor on them. Just to be clear, this is a double top tube frame:
    [​IMG]

    and this is a cantilever frame:
    [​IMG]

    I hope you can see how these frame designs, which are typical of cruiser bikes for decades, place needless restrictions on the physical size and location of a motor installed inside the front triangle. Your bikes' frames do not have these features, but most popular cruiser-style MB donor bikes, for instance the execrable Huffy Cranbrook, do. My own pedal chopper is built on a '90s Dyno Glide cantilever frame. I like it but would never consider motorizing it, for a variety of reasons.

    By the way, I just looked and found a circa 1990 Specialized Hardrock 21-speed mountain bike in good condition offered for $150 on my local Craigslist. That's a normal diamond frame made of round 4130 chromoly steel tubing, with effective cantilever brakes front and rear, and 21 speed index shifting. Its frame is a truss that isn't compromised by being made of curved tubes. It doesn't need a different fork and it doesn't need to be squashed or drilled to fit motor mounts. It could even use billet bar mounts, since its tubes are round and haven't been ovalized by curving them:
    http://www.pro-werks.com/partlist/925/[url] Chalo
     
  15. Kevlarr

    Kevlarr New Member

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    Give it up already.

    Curved trusses have been used for CENTURIES. You know, an arch, the strongest geometric shape?

    curved truss - Google Search
     
  16. Chalo

    Chalo New Member

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    An arch is not a truss.

    And do you see those zigzag pieces that make those arches into arched trusses? They're straight. They wouldn't work nearly as well if they were curved. The arches themselves would work better as trusses, like for like, if they were broken up into straight segments, like a geodesic sphere:
    [​IMG]

    Like it or not, this is relevant to the OP's question. "I've got a cheap curvy cruiser with terrible wheels and minimal brakes. How do I beef it up?" The best way to add strength to that bike is to substitute a diamond frame and good aluminum rimmed wheels. But that means selling it and getting something intrinsically stronger.

    Chalo
     
    #16 Chalo, Aug 21, 2010
    Last edited: Aug 21, 2010
  17. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Question: my personal MTB of choice, of several.....where do I mount the motor?


    [​IMG]

    [​IMG]

    I use my mountain bikes for what they are intended.....mountain biking!!!!!!!! Engineer that!!laff
     
  18. BarelyAWake

    BarelyAWake New Member

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    erm... Hate to throw fuel on the fire - but a triangle is most definitely the "strongest geometric shape" w/o a doubt or debate - arches do come in a close second, the only problem being it's heavily dependent on where the load is... and a bike frame isn't ideal loading for your typical arch (thus the added supports in a cantilever).

    BUT - it's really a moot point, obv cantilever cruisers are more than strong enough for our applications as has been proved by thousands of our members. The only relevant concerns applicable to this thread would be alloys and quality of welds, even gusseting. If the frames had a reputation for breaking in the middle of the arch - then yes, it'd be the a geometry problem - but they don't, they break near the welds... which points to a different problem entirely.

    In the end, the above isn't if a Cranny needs be "beefed up" because it's a cantilever - when it comes down to it, it's a budget bike and that's the only problem. I'd no sooner trust a budget diamond frame than a cantilever as it's not the geometry that is the root of the problem, it's the lack of quality materials and welds evidenced by actual failures and not just theory.

    Given the above - frame style becomes irrelevant as a strength consideration - it's purely personal preference & that has no right or wrong.

    If ya wanted to talk about maximum performance - like power to weight, now we get into minimizing materials, in the interest of the ol' truism "every ounce counts" yer confined to less materials, thus more basic geometric shapes - like the good ol' triangle... That's a topic for a different section tho ;)



    To summarize - this thread is NOT a cruisers vs mountain bike fight, that's pointless and won't fly (we will intercede if needful) Back to the OP's question, which my suggestion would be to just weld in a few gussets if yer worried - or better yet, jus' get a higher quality bike no matter the frame style.
     
    #18 BarelyAWake, Aug 21, 2010
    Last edited: Aug 21, 2010
  19. Chalo

    Chalo New Member

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    Arches are for compressive materials; trusses are for materials that can take both tension and compression. Trusses are more efficient (hence the availability of two-pound bike frames in the real world).

    I dunno, man-- I've seen a lot of reeeally cheap and horrible traditional Indian, Chinese, and Mexican bikes that have nothing on the Cranbrook materials-wise, and whose frames aren't any heavier, but which still last long enough to be handed down from one generation to the next. The difference is design, both overall and in the details.

    There is no doubt in my mind that you could motorize a Chinese Flying Pigeon and it wouldn't bust up multiple times within a short period like Kevlarr's Cranbrook has. And it ain't because the bike is expensive, meticulous, or high quality.
    [​IMG]

    Chalo
     
  20. BarelyAWake

    BarelyAWake New Member

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    Do please feel free to create another thread to discuss this, the poor guy who started this thread is interested in his Cranbrook and it's peculiarities. I think it obvious that were he interested in a diamond frame - he'd have bought one.
     

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