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Paul_Rochdale 09-20-2012 01:06 AM

BMW frame strengthening
Back on the forum for the first time since 2006 when I rode my ST1100 Pan European 17,000 miles across the US from East Coast to West Coast and back. When I returned to the UK I bought a BMW R100GS-Paris Dakar and put it to one side as I intended to restore it and go for a 'big ride' in the future. The dreams 'The Long Way Round' started.

Well six years later and reality has set in. A Big Ride costs money, lots of it. Time is no problem as I'm retired, but money is important as I'm on a pension. And no I'm not about to rent our house out. With reluctance the Pan will have to go. She's monsterishly heavy and i've always struggled to reach the ground. So now is the time to do something with the BMW.

As I intend to strip the bike down to paint the frame, what are the general feelings about strengthening the frame? And where and how should this be done? Around the head stock? I have no intention of crossing deserts or even going off road much but I can see that the rear subframe, especially with heavily loaded panniers might prove a slight weakness. Your thoughts, Gentlemen.

PS I've tried a 'Search' but nothing comes up.

ME 109 09-20-2012 02:27 AM

Good for you man, being able to contemplate a big trip.:D

Before worrying about frame strengthening, I would be more concerned with having correctly functioning suspension for the anticipated total load and placement, and also ensure fork alignment is within tolerance or somewhere damn close to it.
A nice straight front wheel, well balanced, and serviceable, well adjusted steering head bearings.
Then, after testing the bike's handling characteristics fully loaded as intended for the trip, judge what needs to be done.

Nothing further may need to be done. Or the frame may need strengthening.:huh

Clay Spinner 09-20-2012 04:13 AM

In what country do you live? Richie Moore (google moorespeed bmw) should be close to you, or you can send to HPN on germany.

One Less Harley 09-20-2012 05:44 AM


Originally Posted by Clay Spinner (Post 19637049)
, or you can send to HPN on germany.

well that will delay the trip about 2 years.

Paul_Rochdale 09-20-2012 05:49 AM

Me109 (shouldn't that be Bf109?) ;-)

I did ride the PD for a few months until putting it away into dry storage for six (Yes, I'm embarassed) years. So I know she's fine in that respect. She's basically sound but clearly after all this time, she needs a through going over. With the frame on the rusty side, I intend to get that painted (or do it myself) but wondered about strengthening.

This morning I dragged out my two BMWs, the other is an R100/7, onto the drive with a lot of effort. The disc brakes had seized on. Tyres inflated. After a good wash, neither are as bad as I thought. The R100/7 was ridden to work every day for eight years and is a lovely bike.

So that's it for the time being, strengthen or not bother. As it's clearly going to be a 90% road bike, I think the latter.

ontic 09-20-2012 06:11 AM

I think the general feeling usually is that unless you are going to upgrade your suspension and increase travel, and then beat the hell out of it, then there is no need to reinforce the frame.
Furthermore, your 100GS subframe is actually pretty beefy (stonger and heavier than the G/S subframe for example) and should handle heavy panniers on the back without a problem.
Given your described use, I'd save all that reinforcement money for a good set of aftermarket pannier racks and panniers (and maybe a driveshaft:D)

adventure950 09-27-2012 10:53 AM

On the Gs I would consider a second set of rails running from the rear of the seat area down to the mounting point on the frame as the sub frame although strong does wallow a lot when heavy loaded, If you need a set of frame plates I am about to cut a few sets as per my project bike follow thread here as I have a few requests for sets of frame plates so may even cost out a few cnc sets. Jake.

R85/8 09-27-2012 05:10 PM

I don't mean to sound rude, but have you considered travelling light?

I think a great part of riding a bike places is the ease of doing so, and loading it down like a truck, takes the fun out of picking your way along a rough trail.

If you look how little gear round the world cyclists carry, you'll see it's possible.

Then you'll have the money you would have spent modifying your bike to spend on luxuries as you go.

I haven't done anything over 2,000 miles in years now, but I used to be able to get by with an ex army duffel bag with my tent and sleeping bag strapped on top. Being able to detach your luggage each night also means you don't have to worry about theft.

No point in getting away from it all, unless you get away from it all. :)

bgoodsoil 09-28-2012 07:10 PM

You don't need to worry about frame bracing. I jump my bike regularly with boxes and an 11 gallon tank. Granted, I don't jump very high like that :D but I think I'd have broken something if it was going to happen.

As ontic said, the biggest point of failure on that bike is the driveshaft. I'm not a paralever guy so I'll leave advice on that subject to someone with more experience on it. HPMGuy, an inmate, makes a replacement that I've heard good things about.

Good luck on the trip! Make sure to post pictures for the rest of us that are stuck in the real world.

Paul_Rochdale 09-30-2012 03:17 AM

The joys of using a forum and receiving conflicting advice, no matter how well intentioned. Grant Johnson of Horizons Unlimited rode his R80GS around the World and them some more, two up. He had large, very large panniers, and still believes the rear subframe to be a weak point.

Now I almost certainly won't be riding off road, it's not a part of motorcycling which really interests me, but I want a strong, tough, reliable and comfortable touring bike. 99% of the time I ride solo and I have large Touratech panniers and wil get an alloy topbox. But I just look at that rear subframe and it's great overhang over the rear mudguard and think......that needs a couple of diagonal tubes welded in for 'peace of mind'.

BTW I don't have a 'Big Trip' planned now. My dreams of a RTW ride I've now forgotten about. The cost would be massive and my days of living in a tent are gone for good. Any long rides now would be by road to North Cap, Turkey, Eastern Europe and (who knows) another US/Canada ride. Fabulous fabulous countries and equally great people.

Jake, Thanks for the offer of plates. I will have a look at the link and get back to you.

I am ridding the bike of it's high front mudguard and a secondhand low mudguard arrived from Motorworks this week. I also have a set of stainless steel fasteners bought cheaply on eBay.

R85/8, My 2006 17,000 mile US trip lasted for three months and I needed clothing and stuff to last me for that time. Three pairs of pants, three pairs of socks, three t-shirts plus alternative shoes, wet weather clothing and some more. I also took about eight travel books which did weigh a ton so I passed these onto my wife who flew back to the UK with them. It really doesn't take much to fill up top boxes and panniers. If I'd taken a tent and camping equipment, I'd have been well and truly weighed down.

Rucksta 09-30-2012 04:01 AM

If the std muffler is still in use an extra mounting tab from the muffler to the rear of the subframe makes the muffler into an effective subframe brace.
An extra diagonal on the right side adds a lot of strength.

Many of the mounting systems used for panniers create extra bracing depending on how well they are tied back into the frame around the point where rear footpegs would mount,

This may account for some of the variation in reports of bending or no bending with load.

adventure950 09-30-2012 07:51 AM

with regards frame mounts I used to ride with tesch panniers, the frames mounted to the underside of the front footpegs, then at two points on the sub frame and the frame was very rigid box section that incorporated a lower and higher section around the rear of the bike so joining both frames together in effect it became a second weigh bearing subframe for the panniers to sit on. This was a big improvement over the standard mounting points but again only if your loading up to the gunwhales which I did for arctic trips where it worked well, however I now use a very much strengthened sub frame that is very firm - and my wife no longer travels with me so a set of soft panniers, no frames and loads less luggage makes life much easier and gives more than enough space even for extended camping trips. you can see the tesch panniers system fitted on my standard gs below

bgoodsoil 09-30-2012 08:14 AM

@adventure950: What an awesome picture! Man I bet that ride was a blast!


The joys of using a forum and receiving conflicting advice, no matter how well intentioned. Grant Johnson of Horizons Unlimited rode his R80GS around the World and them some more, two up. He had large, very large panniers, and still believes the rear subframe to be a weak point.
Well, yeah. The racks for your boxes are going to need supports. When you say frame strengthening I immediately think HPN-style frame braces. I think that's where the conflicting advice comes from. Adding braces to the sub-frame itself is kindofa hassle since you've got a shock in the way on one side and a pipe on the other. I wouldn't strengthen the frame, I'd strengthen the racks.

When I made my racks I added 1/4" x 1" bars down to the passenger footpegs. The sub frame braces I've seen always go back down to the original lower sub-frame mount. This still allows your sub-frame to 'pivot' around that lower mount and pull back on the top support. If your racks go to a point further back the load will be a lot more stable. On the left side, I didn't have a good way to do that. You can imagine if the top mount came loose, the sub-frame would swivel down around that lower mounting point.

A big +1 on what Rucksta said about using that muffler as a brace on the left. Since you can't go back to a footpeg mount, that muffler is going to be the best 'brace' available on that side.

The real points of failure on the sub-frame are those 1/8" tabs that hang below the top sub-frame tube. All the weight hangs on them. Here's the problem that Grant Johnson, and anyone else that's ridden these things loaded down have found: Do you see how I've got 5 bolts holding this rack on at the top? Only the front 2 are actually bolted to the sub-frame tabs. Scary right!? The rest is hanging off. Those tabs on the G/S sub-frame are a good bit shorter than on the paralever. It's why you'll hear so many people say that the paralever sub-frame is stronger. It's not because all that metal hanging off the back is doing anything: it's because those tabs, that are so weak, are almost twice as long on the paralever. Sorry, I don't have a picture showing just the tabs.

If you look at the 4th bolt back, you'll see that I added a brace that goes up to the very rear of the sub-frame. That's key--It's what's taking the load off those weak tabs. Also, having that right brace go down to the footpeg mount keeps the sub-frame from spinning around the lower sub-frame mount.

bgoodsoil 09-30-2012 08:42 AM

Here's where I did a write-up on the racks:

Here's where I test them:

<iframe width="420" height="315" src="" frameborder="0" allowfullscreen></iframe>

All this rack building/bracing might seem a little extreme: and it is. If you're not riding offroad you can ignore all this. Thousands of people have ridden millions of miles with those stock sub-frames and racks and they were just fine. It's only those of us who don't have sense enough to buy a damn dirt bike that break shit :D

Paul_Rochdale 09-30-2012 09:55 AM

Yes, the hefty silencer is already a sort of brace, so i thought of a single tube on the righthand side, but I see what you mean by the tabs. Thanks for your replies, including the funny ones.:D

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