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  1. #1
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    Question About Spreading Frame to Accomodate Wider Hub

    H have a 1970's Huffy tandem that has a 100mm dropout to dropout width. I'd like to put in a 120mm wide hub. Does anyone have experience fitting a wider hub in a bike that was originally designed for a hub 20mm lower in width. Any advice would be appreciated.

    Pictures of the bike are in the links below:

    http://www.polar.icestorm.com/sfl/im..._tandem_01.jpg
    http://www.polar.icestorm.com/sfl/im..._tandem_02.jpg
    http://www.polar.icestorm.com/sfl/im..._tandem_03.jpg
    Last edited by kc27; 09-15-10 at 03:32 PM.

  2. #2
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    It would be better to have the rear triangle reset for the new spacing. If you don't the axle will be put in a bending stress and shorten the life of the hub.

  3. #3
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    Thanks

    That makes sense about the stress on the hub. I have a couple of questions: How much of a reset range is possible before you risk damaging the frame? Is increasing the space by 20mm considered a major change?

  4. #4
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    20 mm it is too much, 5 mm it is ok but 20 mm it is too much to force it. Agree with davidad

  5. #5
    You Know!? For Kids! jsharr's Avatar
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    I have never cold set a frame, but Sheldon walks you through it here.

    http://www.sheldonbrown.com/frame-spacing.html

    He does not list any info on how far you can spread a frame, but he does say if you are going up the amount you are, you do need to cold set it.
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  6. #6
    Senior Member DannoXYZ's Avatar
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    A 1970's Huffy tandem would most likely be built from some hi-ten tubing like 1020. In which case, bending out each chainstay by 10mm wouldn't cause any problems whatsoever. You'd want to re-align the dropouts afterward so that the dropout faces are parallel. You'll also want to check the chainline and longer BB-spindle may also be necessary.

  7. #7
    DRF aka Thrifty Bill wrk101's Avatar
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    20mm is huge. The most I have done personally is 9mm. Then I would have questions about the quality of the build: drop outs and stays, on that bike. Some of the Huffys I have seen have crimped on dropouts. I would not be comfortable cold setting such mediocre construction.

    While the high ten stays are fine, its the crappy dropouts (and how they are attached to the stays) that would concern me the most.

    Take a picture of that area, can't see that level of details in your pics.

  8. #8
    coprolite fietsbob's Avatar
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    10 mm per side is not much. that's your 20 mm, Id think thw wall thickness of those 1010 steel tubes is generous.

    it costs more to draw tubes thinner, so I know its not like a 531 steel tubeset.

  9. #9
    another retro grouch Mr IGH's Avatar
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    20mm is fine, those chainstays were cold formed, a little 10mm bend is nothing. You will need to re-align the dropouts.

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    Thanks for the responses. I fixed my original post - image 3 is a close up image of the dropouts.

    Wrk101, is your concern that you have to go beyond a 10mm bend on each side in order to reach the point where a permanent 10mm increase in width is achieved?

  11. #11
    coprolite fietsbob's Avatar
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    Probably will, need wider spread then re allign the dropouts to be square to the axle again..
    May I recommend upgrading the Brakes too ? a set of drum Brake hubs
    laced into the wheels will help bring those 2 muscle motors to a stop.

    the 2nd opinion on speed , you can put levers on the stokers handlebars too so when the rider in the back feels the rig is going to fast it can do more than just yell
    slow down !
    Last edited by fietsbob; 09-15-10 at 04:14 PM.

  12. #12
    another retro grouch Mr IGH's Avatar
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    Quote Originally Posted by kc27 View Post
    Wrk101, is your concern ....
    He doesn't know what he's talking about. I doubt he has dropout alignment tools, he's just making claims with no knowledge or experience. Welcome to the 'net....

  13. #13
    Senior Member DannoXYZ's Avatar
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    Quote Originally Posted by kc27 View Post
    Thanks for the responses. I fixed my original post - image 3 is a close up image of the dropouts.

    Wrk101, is your concern that you have to go beyond a 10mm bend on each side in order to reach the point where a permanent 10mm increase in width is achieved?
    It will be fine to spread your stays and re-align the dropouts. By far the majority of load on the rear-end is in the vertical plane. Laterally, loads are quite small and you can even move the stays by hand in that direction. Once the rear-wheel is bolted in, the rear-end is much more rigid laterally. Especially with a wider spacing.

    You can easily accomplish this yourself using the 2x4 Sheldon method. Go slowly and approach your 10mm target per side gradually (use a string wrapped around the head-tube as alignment gauge). Any shop can re-align the dropouts for about $20.
    Last edited by DannoXYZ; 09-16-10 at 12:05 AM.

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    so what would happen if you put a 10 spd hub onto a 126mm rear? spreading the 4mm out- will it hurt the frame or screw up the alignment? thanks,

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    another retro grouch Mr IGH's Avatar
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    Quote Originally Posted by Ride-Fly View Post
    so what would happen if you put a 10 spd hub onto a 126mm rear? spreading the 4mm out- will it hurt the frame or screw up the alignment? thanks,
    I just did this on a nice Trek frame, it was well aligned before I moved the stays out 2mm each. I rechecked the dropout alignment after spreading, the dropouts didn't need to be aligned. 2mm bending is nothing on a steel frame.

  16. #16
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    Quote Originally Posted by Ride-Fly View Post
    so what would happen if you put a 10 spd hub onto a 126mm rear? spreading the 4mm out- will it hurt the frame or screw up the alignment? thanks,
    U can put a 10 speed 130 mm wheelset in a 126 frame w/o any problem. In the case of the OP question 2 cm or 20 mm is like too much to do it w/o doing a cold setting 1st.

  17. #17
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    Thanks everyone for the responses. I appreciate the help because, while I have done some light to moderate bike maintenance, I've never really made any component changes such as going to a wider wheel hub.

    Here is what I hope is not a stupid question: Do the hub widths have to be the same for the front and rear? In my case, I plan on keeping the wheels the same size (26 x 1.75) front and back, its just the width that will differ.

  18. #18
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    OK, I hope you are still monitoring this. The trouble with asking questions on this forum at times is that you don't know the weight to which to give the various (and as you can see above) often contradictory opinions.

    I aligned and reset many, many rear triangles on bikes of all quality levels in an over 20 year career as mechanic, service manager and trainer. In that time some of the stays were bent and the triangles moved out of alignment as well, many more than 10mm. Understanding that I am not there to see the bike I would have little concern about moving each stay 10 mm (in order to increase the total 20 mm). Aligning the dropouts afterward with a proper tool will not strain the dropout/stay attachment at all.

    I would echo the concern about chainline, but it's not as simple as suggested. It's not practical at all to change from your one-piece cranks, so there's no such thing as a longer BB spindle. Also the rear inner chainwheel needs to stay in line with the front chainwheel, so any adjustment with chainline would have to be at the hub. The only exception to that would be if there is some way to add a thin (~2-3 mm) spacer between the chainwheels to make up some of the difference, but that depends on the threading length for the cup on that side, and might cause chainguard rub.

    Adjusting chainline on the hub may be difficult, as you are moving the right side hub locknut 10mm further to the right than before, while you need to have the rear cog fairly well lined up with the chainwheel. You would have to have the ability to move up to 10mm of spacer from the left side to the right, something I would guess is highly unlikely. I need more info on what you are planning for your rear hub/wheel, especially the distance from cog to locknut, but am not sure how you can make this work. See Sheldon's info on chainline.

    Finally, hub widths are pretty much never the same front and rear, so don't worry about that.
    Last edited by cny-bikeman; 09-17-10 at 08:26 AM.

  19. #19
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    cny-bikeman

    Thanks for the detailed reply. I guess I read what I wanted to read in DannoXYZ's reply and missed the significance of what was being said about the chanline.

    With your additional considerations, and after reading Sheldon Brown's article on chainline, it sounds like this is not just a swap-out/swap-in modification. I almost feel that in order to make it work, I would have to get the new rear hub, install it, then determine if the proper chainline can be achieved.

    I think my best options listed in order of least to most difficult are to: live with the bike as a single speed, sell it and buy a multi-speed tandem. or find a multi-speed donor bike (this model was also sold in a multi-speed version) and swap those parts. I was interested in the internal hub to gain multi-speeds without the use of a rear derailleur.

    Thanks again for walking me through the challenges that this type of conversion entails.


    .
    Last edited by kc27; 09-17-10 at 09:33 AM.

  20. #20
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    Glad to help. I assume the multispeed was a 5 speed. An internal hub would be larger width as well. If so then you don't need the same bike as donor - any 26x1.75 wheel with the proper dropout spacing would work, though you would need to change chains and perhaps alter the chainguard.

  21. #21
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    Quote Originally Posted by kc27 View Post
    Here is what I hope is not a stupid question: Do the hub widths have to be the same for the front and rear? In my case, I plan on keeping the wheels the same size (26 x 1.75) front and back, its just the width that will differ.
    Hub widths are rarely the same front and rear. The most common front hub width is 100mm while rear hubs widths include 120, 126, 130 and 135 mm. Your current 100mm rear spacing is unusual and not used on multi-speed bikes.

  22. #22
    Bicycle Repair Man !!! Sixty Fiver's Avatar
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    As far as I know there has never been a tandem built with 100mm rear spacing and if the bike was originally fitted with a coaster hub as many low end bbft's are, the spacing should be 110mm and if it had a 3 speed the spacing should be 114mm.

    5 speed spacing is 120mm, 6 speed and 7 speed road is 126mm, 8 -11 speed road and 7 speed mtb is 130mm, and then we get into real tandem spacing which was 140mm and now the standard is 145mm.

    This is not to say that some tandems are built to use 135mm spacing (mine is built like this) and some have spacing of 160mm although this is something you will only find in a custom tandem or one of our expedition frames.

    Narrower 135mm tandem spacings can be used when a bike is fitted with disc brakes as they do not need the same clearance as the old fashioned drum brakes do and modern rim brakes are also superior.

  23. #23
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    The hub I saw on line was described as Shimano Nexus 8 speed, 120 mm wide. Unfortunately that's as detailed as the description gets.

    I didn't take the wheel off to measure, I just slid an inside caliper as best I could between the two dropouts. And yes, it would be considered a low-end tandem.

    As another poster pointed out, I will be altering the chainline. If I was to attempt this, it seems like the only way to figure it out is to get a wheel, install it, then examine the one piece cranks to see if they can be modified with spacers to be in line with the new rear hub. And that's only if the stock chainwheels would even be compatible with the sprocket on the new hub.

  24. #24
    another retro grouch Mr IGH's Avatar
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    Quote Originally Posted by kc27 View Post
    ...Shimano Nexus 8 speed, 120 mm wide...examine the one piece cranks to see if they can be modified with spacers to be in line with the new rear hub. And that's only if the stock chainwheels would even be compatible with the sprocket on the new hub.
    I think it's a typo, never seen a 120mm Nexus 8, they're usually 132mm.

    I adjust the chainline on one piece cranks with spacers, it's easy to do. As for the chain, sometimes I have to use 1/8" because cool sprockets for one piece cranks are usually 1/8". Here's a bike I adjusted the chainline to match my SA 5-speed hub, it's within a millimeter of perfect:

    IGH's, Dyno Hubs, LED lights and old frames

  25. #25
    Senior Member ColonelJLloyd's Avatar
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    Along the lines of what SixtyFiver has said, I too doubt that the rear spacing is actually 100mm.

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