Topic: Advice on cutting frame and making rear 'hoop' for cafe seat and battery holder

[bmarshall]

Did a search but found very little info. I and wanting to build a rear hoop to match the countour of the rear of a cafe seat and hold hte electronics and battery. I know that Benji sells on but it is pretty $$$.

My question are where to cut. how to bend the tube, what size tube to use etc... Can anyone help with advice or pix?

[wannabridin]

Well one thing to consider is that benjies piece is engineered and ready to weld up! Plus it already has the compartments for a clean install, might be worth the expense...

Otherwise I'd say to bend it, come up with the shape you want with some MDF or plywood, then clamp one end of tube, I'd say some 1/8" - 3/16" wall would be fine, and the heat up the pipe while bending it around the die.  Then sleeve the ends to fit into the frame behind the shock mounts and do a plug welg to hold the sleeve on the frame and hoop...

I hope this helps!

[bmarshall]

yes, it does help, what is a plug weld? Drilling a hole and filling it with weld?

[GStarIndustries]

Im definitely not trying to knock Benji, but I have his rear hoop on my bike and for the money I think its way over priced!
I think someone with novice fab skills could make one for less then 50.00. Again Im not trying to disrespect, I'm just very anal about the quality of a product VS price. Benji hella hooked me up when I needed a hand.

Here are a few pics of mine for reference.

[Nikkisixx]

Hey GStar, that looks very tidy.  Would you mind posting a pic from the side (profile)?

[MilehighCB]

If you still have the stock grab bar, cut it down to make an arc. That's what I did. The tube size is smaller than the frame so it fits into the frame well. It just took a few cuts to make a nice loop. Super cheap, and when welded correctly, strong as well. I have picked up my bike with mine without any issues.

Hope it helps....

[articblue]

Awesome pictures, I needed some ideas for how to / what to do with my current seat setup.

[slowjo]

I had a Amish guy that I work with try to bend a bar for my seat. He said that he had a bender but it was for flat stock. The pipe that I used kinked up. I later learned that you should plug one end and fill it with sand then plug the other end and bend. So I just used a piece of 1 1/2 flat stock and bent it around a template I made out of wood. Since its under the seat you can't tell that it's not made out of round bar.

[GStarIndustries]

No sweat mate!

One of the left! dont mind my plate.



And the right...



Also a side note. You can easily buy a U bend for a few dollars that is already pre bent...

[bmarshall]

Yes, Benji is a good guy, he answered all of my emails quick and with good info, but I'm making this a budget build. Unfortunately there was no grab bar on the bike so I may need to fabricate something. Your hoop looks really good though.

[Nikkisixx]

Thanks GStar!   

[wannabridin]

A plug weld is made by drilling a hole in the outer tube and then inserting the sleeve and welding them up.  Make sure to do it on both sides of the sleeve, aka the frame side and the hoop side.  Don't forget the gusset like what benjie has done to continue the shape of the shock mount to the hoop.  This is where the strength comes from with the hoop.  Make sure to get good penetrating welds, but be careful to not burn through the 35 year old steel in the frame.  While it's a good frame, Honda kept it cheap by using lower quality steel in the frame.  I plan on purchasing a pre made hoop from the net and tweaking it to suit my needs.  Hope this helps!!

[cadaver]

you can make your own or go out and buy one of benjies, that's what I did because I didn't have the resources to make my own, as for the the price and install...its all up to you, but I was happy in the end result on how it looked.. lol wire management is a little better now .

[bmarshall]

A plug weld is made by drilling a hole in the outer tube and then inserting the sleeve and welding them up.  Make sure to do it on both sides of the sleeve, aka the frame side and the hoop side.  Don't forget the gusset like what benjie has done to continue the shape of the shock mount to the hoop.  This is where the strength comes from with the hoop.  Make sure to get good penetrating welds, but be careful to not burn through the 35 year old steel in the frame.  While it's a good frame, Honda kept it cheap by using lower quality steel in the frame.  I plan on purchasing a pre made hoop from the net and tweaking it to suit my needs.  Hope this helps!!

Have you seen any pre-made hoops besides Benji's?

[wannabridin]

i have not seen any, either home made or benjies.  i'm going to trace my seat cowl and have it run just inside the cowl i think.  maybe have it run halfway into the cowl so theres still some seen underneath, i'm not 100% yet.  either way, i'm going to run the hoop with the "floor" welded up so to act as a road crud and water barrier.  keep us posted on what you decide to do!

[fastbroshi]

  Staggerlee has one on his 550 he made from some old cut up handlebars.  If you don't know how to weld, you're up a creek any way you look at it because your going to need to weld whatever you put on there.  For everything to be stout and proper that is. 

[bmarshall]

I just bought a $89 HArbor Freight welder for this purpose. Since it's not a load bearing part even my bad welds will be OK. I have heard of the sand trick to keep the tube from collapsing, I like the part about cutting a template from plywood and using it as a jig. Now the hard part is deciding on a seat, what are you all using, brand, model etc...

[the architect]

When I did mine, I made a mandrel from 3/4" mdf (chamfered on one side to help hold the pipe I was bending).  I clamped the pipe at one end and drew the free end around the mandrel, little by little.  I got a kink-free radius with no sand, water/ice, etc.









Sorry, I didn't get any photos of the mandrel and the bending portion.  My back was sore the next day, though    , as I didn't heat up the pipe before bending.  My process was very similar to the one found here:  http://www.instructables.com/id/How-to-bend-tubing/

One word of caution, though.  Despite my calculations and mocking-up, I ended up with the rear tire rubbing the underside of my frame hoop when loaded with passenger and riding on rough streets/bumps  .  I ended up having to source rear shocks that are ~1" longer to solve this.  Be thorough and be sure to leave yourself plenty of space for suspension travel.

[wannabridin]

nicely done.  i would of rather made mine out of a single piece of tube though, to avoid the angles you have where you welded it up.  or at least ground this down smoother.  either way, nice process and good results!

[Staggerlee]

  Staggerlee has one on his 550 he made from some old cut up handlebars.

It's true; here's a pic after welding it to the frame.



The 7/8" OD of the bars is a perfect compression fit into the frame tubes; I think I pounded it in about an inch before welding.  It's hell for stout, I've lifted the ass end of the bike up by the hoop before, no problem.

Here's a shot all together; I modified the factory battery box to work with the smaller AGM battery that I'm using.

[wannabridin]

nice work!!  looks good, and no need for gussets even!!  it seems to be the popular thing people are doing, modifying the stock batt boxes to hold an agm.  i'll probably just weld some nuts to a plate and bend up a piece of aluminum and use some screws, like travelers setup.  nice work though!!

[Cheese]

I have been talking to a metal fab guy who says he would have to buy a jig he doesn't have for the width I requested. Said he would have to sell about 12 of these hoops to make it worth his while. At $30 a piece I was thinking others might want to jump on the bandwagon to get a 1" tube hoop bent with 6.5" gap and one foot long so you could cut to length. Anyone interested in getting one? I need two for my bikes I am building. Any other input on the design of it?

I will be welding my own pan in it and don't think I want to move the battery up that high. I would rather keep the weight low as possible.

Gonz

[Mtmooradian]

I ended up making the whole back half of the frame

[Mtmooradian]

Also didn't bend into a hoop, the 90s give room for the tail light

[754]

 Just put 2 90's together.. gives a wide variety of profiles..