Listen to your elders

Discussion in 'Motorized Bicycle General Discussion' started by Agreen, Feb 8, 2016.

  1. Agreen

    Agreen Member

    Joined:
    Feb 10, 2013
    Messages:
    787
    Likes Received:
    2
    Public service announcements:

    Ditch the tensioner now.
    -and-
    Tom (2door) should be listened to at all times. Your bike will appreciate you for it.

    I could probably spend all day pouring through the threads on here, and still not count all the times Tom has said to ditch the chain tensioner. Yet, I have not heeded the wise words.

    I finally got around to picking up some half links. I searched a little around town for some regular 1/8" bike chain half links, but nobody seemed to carry them in stock. My final stop was fruitful, but not for 1/8" bike chain. When asked, he replied "No, but I have these huge ones...and you can have those!" I asked for a caliper, and it sure enough turned out to be 415 chain. Yay free!

    Anyway, moral of the story is to listen to Tom! The bike is SO MUCH QUIETER! I never knew how much noise the cheap nylon wheel made until it was gone. Well worth it. I'm also no longer afraid of the impending tensioner-in-the-spokes trick they like to pull sometimes.
     
  2. 2door

    2door Moderator
    Staff Member

    Joined:
    Sep 15, 2008
    Messages:
    16,301
    Likes Received:
    25
    Thanks for the kind words, Green. I'm glad the no-tensioner route is working out for you.
    Of course we have to consider those who have frames that make running without a tensioner difficult or impossible. They are the ones who need to explore the alternatives.

    My biggest concern is the kit supplied tensioner and the way it gets mounted with no consideration for the consequences if it loosens and rotates into the spokes. There is so much good information here offered to prevent that from happening. It's too bad that every new builder doesn't read it before the inevitable happens. I just don't want anyone to get hurt and that's a possibility unless the tensioner problem is addressed.

    Good luck with your bike and enjoy the smooth, quiet ride.

    Tom
     
  3. Agreen

    Agreen Member

    Joined:
    Feb 10, 2013
    Messages:
    787
    Likes Received:
    2
    Luckily I had neither issue. The GT2-A Skyhawk frame is actually well thought-out, and the chain doesn't come close to the frame at all. Also, the chain stays have an oblong cross section, so even if you do use the cheesy nylon supplied tensioner, it will not rotate on you.

    The issue I ran in to that caused this was that my exhaust bracket failed and I tried to undo the tensioner to make it a dual purpose "exhaust mount/tensioner" bracket. Anyway, the bolts snapped when I went to loosen them and left me with a floppy chain and exhaust. That's when I noticed how worn the roller had gotten. It's almost all the way down to the bearing. I looked around the hardware stores for a suitable replacement, then that bug you put in my ear about going tensioner-less kicked in and I finally caved in.

    Also, I learned a lesson about spring tensioner too. I built one for another MAB out of hardware store parts. Unfortunately, when you go to pedal start the engine, it stretches the spring and can either snap it, deform it, or rip it right off. So... I don't recommend them.

    And the words smooth and quiet don't do it justice! With a rear exit exhaust, sound deadening material, and no tensioner, it's silky and buttery now! Riding has always been my moment of zen, and now it's even more so.
     
    #3 Agreen, Feb 8, 2016
    Last edited: Feb 8, 2016
  4. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

    Joined:
    Feb 6, 2010
    Messages:
    2,787
    Likes Received:
    1
    I, unfortunately, have found no other mounting method that allows me to discard the tensioner/guide, and still avoid having the drive chain saw its way through the chain stay. And believe me, I have tried, because early on I was desperate to ditch the thing also. But even with the smaller 38 tooth (yes, 38, not 36) sprocket, it just wasn't meant to be.

    So I would add this advice: if you MUST use a guide wheel on your drive chain, and can find no other way to do without, get the most robust one that you can and mount it as solidly as possible. The ones with four mounting bolts are great. I do not know enough about the sprung ones to honestly recommend them.
    Then, you'll likely need to bend the guide wheel bracket so that the track of the wheel is exactly aligned to be parallel with your drive chain. The wheel's axis bolt should be exactly perpendicular. The chain stay it will be mounted on *is not* usually parallel to the tire or the drive chain; it angles inward as it gets closer to the bottom bracket. So, if the guide wheel is in alignment with the chain stay, the chain will run along it slightly diagonally, and there's a chance it will put a side-load on the guide wheel's flanges. If you mounted it rock-solid, then the chain will tear up your guide wheel. If it's only mounted "well enough" then the side load from the chain is liable to drive your guide wheel right into your spokes.

    You also want to make sure that the guide wheel's track is exactly underneath the chain, not off slightly to one side, and you want to be sure that the guide wheel's axis bolt is exactly level with the drive chain. It's a lot to check on and think about, but if you do it now it will save you a great many problems later and maybe even disasters.

    And finally, you really do want to check the thing before every ride. I doubt you'd ever regret doing so. (It's on my checklist of things I check before riding.) Cruising along at 25 mph or more is not the time to find out that the chain tensioner/guide wheel was loose.
     
  5. 2door

    2door Moderator
    Staff Member

    Joined:
    Sep 15, 2008
    Messages:
    16,301
    Likes Received:
    25
    Allen's advice is critical. That tensioner bracket will need to be bent/twisted to get the wheel to align with the centerline of the chain path. This is never mentioned in the poor instructions that come with the kits.

    A subject (suggestion) that hasn't been mentioned much lately is using a skateboard wheel as a tensioner. There are several good threads detailing how this is done. Type 'skateboard wheel' into the 'Search' box and see what others have done.

    The most important thing is to use a wheel that is one piece and not layered. A good quality urethane wheel seems to work best. Good luck.

    Tom
     
  6. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,471
    Likes Received:
    43
    I've found that most chain stays are angled a bit out at the axle, if chain is rubbing on it moving the tensioner as far back as possible may fix it (sometimes requires a 1/2 link to get it back there.
     
  7. ZipTie

    ZipTie Active Member

    Joined:
    Jan 8, 2016
    Messages:
    741
    Likes Received:
    30
    I will for sure have get some half links then for my GT frame chain. I have the 4 bolt tensioners now and would love to get rid of them too. I squeezed my chain stays together 2 inches and may not be able to remove mine. Also can you post a new picture or two of your tensioner-less bike with the long exhaust and how and where you mounted it...if and when you get some time. Thanks
     
  8. YesImLDS

    YesImLDS Member

    Joined:
    Jun 29, 2013
    Messages:
    951
    Likes Received:
    0
    I'll agree with the first part, but the second part is iffy! Sorry Tom! Ha! At least a nice spring tensioned upgrade would be better than the stock tensioner. I lost 2 rims to the stock one finding it's way into the spokes. Was not a fun time.
     
  9. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

    Joined:
    Mar 20, 2008
    Messages:
    6,169
    Likes Received:
    18
    I've tried all those skateboard wheels & and mini sprockets for tensioner wheels... I honestly think the stock nylon plastic wheel works very well!! (^)

    As Tom said above, you must bend the bracket to make the wheel line up with the chain line & you also have to fasten the bracket to the frame so it will never move into the spokes!
    I always cut off the top of the bracket & weld it to the chain stay of the frame. ;)
     
    #9 Venice Motor Bikes, Feb 11, 2016
    Last edited: Feb 11, 2016
  10. Agreen

    Agreen Member

    Joined:
    Feb 10, 2013
    Messages:
    787
    Likes Received:
    2
    This was taken at night time a couple days ago. I haven't been home in daylight long enough to work on things, let alone to take decent pictures.

    [​IMG]

    What you're seeing here is that I have cut the tensioner bracket and converted it to an exhaust hanger. And the shiny object above it is a wheel reflector.

    As far as spring tensioner go, the big thing I didn't think about when using one is that the top chain goes slack when you release the clutch. It tenses up the bottom chain and pull starts the engine. With enough slack... you could be coming to a grinding halt when the chain bunches up on the drive gear, or it just pops off completely and tangles around other stuff. It was a well though out design on my part (I was pretty proud of it actually). Unfortunately, it's just a bad idea. The skateboard wheel was my next choice, but I don't know of any skate shops around locally, and you apparently can't buy a single wheel online.

    I completely agree with the twisting of the tensioner bracket. I did that on all of my builds and never thought about it twice.
     
    #10 Agreen, Feb 11, 2016
    Last edited: Feb 11, 2016
  11. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

    Joined:
    Mar 20, 2008
    Messages:
    6,169
    Likes Received:
    18
    Here's how I cut & weld the stock tensioner to the frame...

    image-404766476.jpg
     
    #11 Venice Motor Bikes, Feb 11, 2016
    Last edited: Feb 11, 2016
  12. wheelbender6

    wheelbender6 Active Member

    Joined:
    Sep 4, 2008
    Messages:
    3,816
    Likes Received:
    10
    Agreed. Listening to 2Door will save you time and trouble.
    I also agree with you in principal, Agreen. But, when I installed a motor sprocket that bolted to my disc hub, the chain stays interfered with the path of the chain. I had to install the tensioner to route the chain above the chain stays.
    [​IMG]
     
  13. 2door

    2door Moderator
    Staff Member

    Joined:
    Sep 15, 2008
    Messages:
    16,301
    Likes Received:
    25
    That sort of looks familiar. I think I've seen that idea somewhere

    Great minds do think alike. :)

    Tom
     

    Attached Files:

  14. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

    Joined:
    Feb 6, 2010
    Messages:
    2,787
    Likes Received:
    1
    Even I will concede: if you must run with a guide wheel - a welded-on one is best. When the weather warms a bit, I mean to practice my welding. If I get good enough in a decent amount of time, I'm welding a bracket on. If I don't think I can do a nigh-perfect weld, I'm going to talk to a mechanic friend. I may still have him do it, just to be safe.

    So yeah, if you can weld rather well or can find someone who does, definitely do that. Make sure whoever welds understands the geometry of the situation.
     
  15. 2door

    2door Moderator
    Staff Member

    Joined:
    Sep 15, 2008
    Messages:
    16,301
    Likes Received:
    25
    If you opt for a welded tensioner bracket you might want to explore the type that bridges between the seat and chain stay. There are aftermarket bolt-on brackets like this one available too.

    Like any bracket it must be installed to align the wheel with the chain.

    Tom
     

    Attached Files:

  16. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,471
    Likes Received:
    43
    got a decent builder in town that welds them - his customers come in for work & I have to charge them to lift the motor a bit because the tensioner is at end of slot & can't be slid back a bit
     
  17. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

    Joined:
    Feb 6, 2010
    Messages:
    2,787
    Likes Received:
    1
    I like that kind too, Tom. I may go with that. If I'm going to weld onto an antique frame, I may as well do it the best way possible. I don't plan to ever convert the bike back or to ever sell it, and being an old Higgins its value outside of sentimental isn't that high. I'm going to keep that bridge-style bracket in mind.
     
  18. ZipTie

    ZipTie Active Member

    Joined:
    Jan 8, 2016
    Messages:
    741
    Likes Received:
    30
    That's the best chain tensioner install I've yet to see. Nice work!
     
  19. 16v4nrbrgr

    16v4nrbrgr New Member

    Joined:
    Mar 17, 2012
    Messages:
    1,718
    Likes Received:
    1
    It's worthwhile installing an idler sprocket in place of the plastic roller, it will run smoother and keep a constant tension because it interfaces with the rollers on the chain versus the side plates which are typically fiddle shaped.
     
  20. Allen_Wrench

    Allen_Wrench Resident Mad Scientist

    Joined:
    Feb 6, 2010
    Messages:
    2,787
    Likes Received:
    1
    That's not a bad idea either.
     

Share This Page