XS850 - Monoshock & USD Fork (pics pg 13)
- Thread starter treitz
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dualero
Been Around the Block
Re: XS850 Cafe - Monoshock + Modern Front End
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It does not matter if the frame design as is now is able to handle hard riding. Because I'm pretty sure the bike can handle a lot of stress as is now. Important is the fact that will this bike whistand the fatigue loads of hard riding that this bike could be sustained to through its "new" life and not being a time bomb? That's the real questionBigsherm said:
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Re: XS850 Cafe - Monoshock + Modern Front End
With all due respect, you don't appear to understand the magnitude and direction of forces in a monoshock frame. Start with copy of Tony Foale's book - you may already have a copy. On a twin shock frame, there is very little force on the swingarm pivot and all of it is vertical. On a monshock the direction of force is entirely different and removal of the rear triangle removes all the bracing to that pivot.
And the greater the shock angle, the higher the resulting front-aft loads.
Add in higher side loads when cornering from fat sticky modern tires and now you have a situation where the rear end will flex far more than a stock chassis.
I have a similar conversion in the shop that we did and the frame will probably be cut up and replaced with a twin shock because so far we have not come up with an adequate way to make it safe for the long term. It looks wicked, but it isn't safe to ride hard as it is right now.
barreto said:
With all due respect, you don't appear to understand the magnitude and direction of forces in a monoshock frame. Start with copy of Tony Foale's book - you may already have a copy. On a twin shock frame, there is very little force on the swingarm pivot and all of it is vertical. On a monshock the direction of force is entirely different and removal of the rear triangle removes all the bracing to that pivot.
And the greater the shock angle, the higher the resulting front-aft loads.
Add in higher side loads when cornering from fat sticky modern tires and now you have a situation where the rear end will flex far more than a stock chassis.
I have a similar conversion in the shop that we did and the frame will probably be cut up and replaced with a twin shock because so far we have not come up with an adequate way to make it safe for the long term. It looks wicked, but it isn't safe to ride hard as it is right now.
Re: XS850 Cafe - Monoshock + Modern Front End
but personally i would double up on those tubes piggyback tandem style
you are doing a fantastic job on the fabrication, some tapering gussets at the top tube connection to the backbone would really help and you have the skills to pull that of beautifully as wellbarreto said:
but personally i would double up on those tubes piggyback tandem style
barreto
New Member
Re: XS850 Cafe - Monoshock + Modern Front End
All of the feedback and criticism is great. It is always difficult to adapt an older frame to a newer suspension design, but I think it will be sufficient when the fabrication is completed. The frame is not done at this point. I put it on the ground to make sure the stance is what we wanted, but there are several components to be added before it is completed.
Just for a little background on myself, I grew up in a machine and fabrication shop and am a mechanical engineer whose primary job is designing hydraulic-powered industrial equipment, so I'm very familiar with designing high-stress, high-cycle parts and machines. I am not claiming to be the authority on suspension design, but I will be doing everything possible to make sure it is done correctly.
That being said, suggestions and constructive criticism is welcome.
All of the feedback and criticism is great. It is always difficult to adapt an older frame to a newer suspension design, but I think it will be sufficient when the fabrication is completed. The frame is not done at this point. I put it on the ground to make sure the stance is what we wanted, but there are several components to be added before it is completed.
Just for a little background on myself, I grew up in a machine and fabrication shop and am a mechanical engineer whose primary job is designing hydraulic-powered industrial equipment, so I'm very familiar with designing high-stress, high-cycle parts and machines. I am not claiming to be the authority on suspension design, but I will be doing everything possible to make sure it is done correctly.
That being said, suggestions and constructive criticism is welcome.
barreto
New Member
Re: XS850 Monoshock Cafe (+ Modern Front End)
A quick update on the frame fabrication. After getting some feedback on how the frame needs to be strengthened, I looked at how best to fit more structure into the frame. Here is how I'm planning on adding some beef to it without adding too much weight. I'm going to add a vertical tube on either side of the frame and tie them together in several key places. Keep in mind, this is a preliminary fitting to make sure everything cleared on both sides. I also need to make sure the engine can be removed before anything gets welded further.
A quick update on the frame fabrication. After getting some feedback on how the frame needs to be strengthened, I looked at how best to fit more structure into the frame. Here is how I'm planning on adding some beef to it without adding too much weight. I'm going to add a vertical tube on either side of the frame and tie them together in several key places. Keep in mind, this is a preliminary fitting to make sure everything cleared on both sides. I also need to make sure the engine can be removed before anything gets welded further.
focusinprogress
City Limit Moto:Parts-Service-Apparel (716)8038606
Re: XS850 Monoshock Cafe (+ Modern Front End)
out of curiosity, what did you end up with trail-wise swapping the front end? I'm working out something similar with GSXR750 parts and with stock GSXR triple trees the trail was 6.25" (eek!) I did happen to notice your xs850 started out with non-leading axle forks but my xs750 had leading axle forks. Makes me wonder if the neck angle on the frame was different for the non-leading-axle versions. I'm making custom triple trees from scratch with more offset to bring the trail closer to 4.25-4.5" for mine....and made up some rotor adapters to use RC51 rotors on stock wheels.
out of curiosity, what did you end up with trail-wise swapping the front end? I'm working out something similar with GSXR750 parts and with stock GSXR triple trees the trail was 6.25" (eek!) I did happen to notice your xs850 started out with non-leading axle forks but my xs750 had leading axle forks. Makes me wonder if the neck angle on the frame was different for the non-leading-axle versions. I'm making custom triple trees from scratch with more offset to bring the trail closer to 4.25-4.5" for mine....and made up some rotor adapters to use RC51 rotors on stock wheels.
treitz
Over 1,000 Posts
Re: XS850 Monoshock Cafe (+ Modern Front End)
Thanks for posting the update on the frame Luke.
I don't know the answer to this exactly... but I can tell you that on the 850 it is pretty close to stock because, as you mentioned, the 750 has the leading axel which the 850 does not.
And nice work on that adapter to run the stock wheel with those calipers! Looks great.
Thanks for posting the update on the frame Luke.
focusinprogress said:
I don't know the answer to this exactly... but I can tell you that on the 850 it is pretty close to stock because, as you mentioned, the 750 has the leading axel which the 850 does not.
And nice work on that adapter to run the stock wheel with those calipers! Looks great.
focusinprogress
City Limit Moto:Parts-Service-Apparel (716)8038606
Re: XS850 Monoshock Cafe (+ Modern Front End)
Thanks for the kind words! many hours on the lathe lol. I have two xs850's as well that both have the leading axle forks too....I think the difference is "standard" versus "special" models....the standards seem to have the knee-dent style tank and non-leading axle forks, while the "special" has a more tear-drop style tank and leading axle forks.
hbc said:
Thanks for the kind words! many hours on the lathe lol. I have two xs850's as well that both have the leading axle forks too....I think the difference is "standard" versus "special" models....the standards seem to have the knee-dent style tank and non-leading axle forks, while the "special" has a more tear-drop style tank and leading axle forks.
treitz
Over 1,000 Posts
Re: XS850 Monoshock Cafe (+ Modern Front End)
That is correct. Standard is the knee dent style tank vs. the tear drop on the special. However I didn't realize they had a different fork setup. I know the special was meant to be more comfortable/cruiser style, so that could explain it.
P.S. I have the stock set of forks from this bike still (along with a million other parts) if you want them. I can message you a long list of parts if you need anything.
focusinprogress said:
That is correct. Standard is the knee dent style tank vs. the tear drop on the special. However I didn't realize they had a different fork setup. I know the special was meant to be more comfortable/cruiser style, so that could explain it.
P.S. I have the stock set of forks from this bike still (along with a million other parts) if you want them. I can message you a long list of parts if you need anything.
