Footpeg Location

[pmk]

2 hours ago, feetupfun said:

Those percentages are not swingarm length/wheelbase. They are footpeg to rear axle/wheelbase

Yes, I messed up posting swingarm.  It was late and I had both this topic and the one I linked open.  Thats_A_Five posted swingarm length and it was on my brain when it should not have been.  My measurement and calculation was as you described, actually using your posted formula.

This morning I found the variation between your 26.2% and my 27.2%.  Your numbers were likely taken on an MAR with oem stock footpegs, on stock mounts.  Those footpegs were small overall and certainly not a large platform front to rear.  This morning, I went back out and remeasured.

My current setup has oem mounts on the frame, but uses Kawasaki KX footpegs.

Last night I measured from the center of the footpeg, the KX peg, to rear axle.  That came in at 14”.  Remeasuring this morning, as if oem MAR footpegs were installed, the length decreses to 13.5” from footpeg center to rear axle.  That 1/2” difference accounted for a 1% change.

This became an eye opener when seeing where another person stated 29% was a good base number.

Granted there is some minor measuring errors since the measuring was done directly with a tape measure vs obtaing the true dimension by dropping plumb bobs to the floor.  Essentially, the tape meaure is close enough.

Overall, as a general guide in helping to determine where to mount footpegs, all the info has been a huge help.

 

[b40rt]

Aah, a real topic at last (though I do think you should establish what ratio your running at ?)

I would argue that before you can make a reasoned statement for the benefit, or otherwise, to moving footrest, the dimensions of the rider is paramount. A taller rider with rests down and back, and higher bars, probably has a similar weight distribution to a shorter rider in standard position. 

Greg above mentions modified bikes pushing the front end, which is possibly true riding without touching the clutch. But for those of us that have adopted the one finger approach  ,killing the flywheel effect by dipping the clutch, this isn't a problem in my experience.

[pmk]

2 hours ago, sherpa325 said:

The thing to remember here is that these bikes were designed by riders that were the best in the world at that point in time [Mick Andrews]. So he and other factory riders would have spent numerous days testing footpeg positions. All design work is a compromise and you rarely get anything for free. Moving the pegs forward will make the front end heavy  and moving them back will make the front light and more than likely push the front forwards in tight turns but at the same time improving rear traction. Lowering the pegs and fitting new wide style pegs is one of those situations where in my opinion there are no downsides, ie you get something for nothing, the bike is more stable, riding position is improved, its all good if you can keep your feet away from the rocks. My advice would be to keep the original position forward/back lower them as far as is practical and fit some good quality pegs that have washers that allow you to move them forward or back in the mounts thus giving you some room for fiddling. I am not sure where the fad for moving pegs back has come from as the bikes now have far superior tyres than were available in the 70's, so rear traction is much better without moving the pegs back and compromising the steering. All modern bikes would have their pegs mounted a good bit further forward than a traditional twinshock

Cheers Greg

 

 

Greg, yes.  Prior to your post, I decided that on the MAR, the front / rear location seems somewhat optimized as delivered back in the day.  For my friend, that is tall, the footpegs are being moved downward.  How much is unknown at this point, but is the next variable to decide upon.  Another post mentioned to lower them to the height of the axles.  Next will be running a string from axle to axle and seeing how much change this creates and if the position is too low, too high still or possibly appears good.

I have been looking at various photos of many OSSA MARs with relocated footpegs.  The most extreme is 50mm down and 50mm aft.  The owner mentions his goal was modern bike feel, and says it is now that way.  My current though is as I mentioned simply downward with no change front to rear.

[pmk]

7 minutes ago, b40rt said:

Aah, a real topic at last (though I do think you should establish what ratio your running at ?)

I would argue that before you can make a reasoned statement for the benefit, or otherwise, to moving footrest, the dimensions of the rider is paramount. A taller rider with rests down and back, and higher bars, probably has a similar weight distribution to a shorter rider in standard position. 

Greg above mentions modified bikes pushing the front end, which is possibly true riding without touching the clutch. But for those of us that have adopted the one finger approach  ,killing the flywheel effect by dipping the clutch, this isn't a problem in my experience.

Yes, ratios are being determined, this morning with fresh eyes and brain, I am double checking my late night efforts I posted earlier.

His bike already has bar risers.  Pulled the bars foward slightly also.

You mention a taller rider wanting the pegs down and aft.  What is your opinion on moving them aft for the tall rider?  Increased room or some other factor being changed?

Months ago, on another website I asked if anyone knew how tall Mick Andrews is / was back when the MAR was designed.  Simplya curiousity to have an idea of how tall the target rider for an MAR was back when they were new.  Sadly, his height, posted by others, varied a bit.

 Regarding the use of the clutch.  The sections in our local events, some certainly require use of the clutch to get the bike to corner tightly, while other times, the sections seem more old school where you simply ride using throttle control, balance, and turning skills.

I will say, that while accomplishing all this research, and since I am modifying his frame, I remain curious about my own MAR and me as a rider shorter than my friend.  Pretty certain I am either making or buying some risers for my handlebars.  Not interested in lowering my forotpegs just yet since my frame is recently powdercoated.

[b40rt]

I've just checked footrest mounting position in relation to line between axles, even although footrests have been moved down and back, they are are still about 40 mm above. 

Lineaway hates bar risers, and if riding modern trials at higher level I'm sure he is right, for more classic events they are fantastic. I do occasionally hit the cross bar, but not enough to consider change. 

Regarding one size fits all frames, Danilo Galeazzi, swm works rider and multi Italian champion, moved his footrests forward to suit his size and style. 

[2stroke4stroke]

I seem to recall the MAR had a comparatively short wheelbase, the MK 1 particularly so.  This might affect measurements and percentage comparisons with other bikes.

[pmk]

1 hour ago, 2stroke4stroke said:

I seem to recall the MAR had a comparatively short wheelbase, the MK 1 particularly so.  This might affect measurements and percentage comparisons with other bikes.

Actually, 51.5” is what I measured and that matched what feetupfun measured a few years ago.  Not the shortest nor the longest, but does match what someone else posted that Miller, I assume Sammy Miller, apparently says 51.5” is optimum on the older bikes.

Regardless, this is quite the learning lesson prior to making some cuts to the frame.

[guy53]

I was very tempted to temper with the frame of my 250 TY a while back. Lucky for me, that was a TY and there was at the time some bare frame for sale at a very reasonable price, so I bought one and made some modification. The first one was footrest location, I'm 5'8'' ( short ) and I still like the 1 3/8 inch lower and 1 3/8 inch back. I'm not saying that it is the right location for your MAR but maybe the position I like, you would not.

Guy

[lineaway]

19 hours ago, pmk said:

Footpegs on my buddies and my MAR have been swapped to Kawasaki footpegs.  Position remained the same.

My buddies MAR is going to be modded.  He currently runs bar risers, guessing about 1 1/2” maybe more and slightly forward.  Certainly noticable compared to my MAR with no risers.  We both run the tallest Renthal bars.

Lowering the footpegs is primarily to accomodate his tall height.  

 It does not matter how tall you are, foot peg and handlebar position is all the same. Take a look at Dougie Lampkin`s bikes, nothing done for his height. Your body has a  proportional relationship between wingspan and height. Have you ever heard of short people raising the pegs? What is funny is tall people are lazy when it comes to bending their legs. If they would, the advantage they have over short riders is considerable. 

[pmk]

32 minutes ago, lineaway said:

 It does not matter how tall you are, foot peg and handlebar position is all the same. Take a look at Dougie Lampkin`s bikes, nothing done for his height. Your body has a  proportional relationship between wingspan and height. Have you ever heard of short people raising the pegs? What is funny is tall people are lazy when it comes to bending their legs. If they would, the advantage they have over short riders is considerable. 

The bike getting the footpeg mod, the owner has had several back surgeries, so any bending over forward is not comfortable for him.

As for me wanting to raise the bars some, trying to find oem height bars the same as original MARs in something other than steel has been impossible so far.  Currently running Renthal bars, the tallest trials 7/8 bars they offer.  Still a bit lower than oem.

So the modified bike will get footpegs lowered, and bar height reset for the riders comfort.

[fourex]

1 hour ago, pmk said:

The bike getting the footpeg mod, the owner has had several back surgeries, so any bending over forward is not comfortable for him.

As for me wanting to raise the bars some, trying to find oem height bars the same as original MARs in something other than steel has been impossible so far.  Currently running Renthal bars, the tallest trials 7/8 bars they offer.  Still a bit lower than oem.

So the modified bike will get footpegs lowered, and bar height reset for the riders comfort.

I'm a fan of the S3 adjustable bar clamps on my bikes, upside being a 13-15mm lift and fore/aft adjustability, downside being only available for fat bars and on a MAR you have to drill out the 7 mm top yoke threads and heli coil to 8mm.

Here's a pic of the mod on my mk2 with tall Jitsie fat bars which when combined with the S3 clamps are actually too tall for my liking, I'm 6ft.

 

[pmk]

5 hours ago, fourex said:

I'm a fan of the S3 adjustable bar clamps on my bikes, upside being a 13-15mm lift and fore/aft adjustability, downside being only available for fat bars and on a MAR you have to drill out the 7 mm top yoke threads and heli coil to 8mm.

Here's a pic of the mod on my mk2 with tall Jitsie fat bars which when combined with the S3 clamps are actually too tall for my liking, I'm 6ft.

 

 

On my bike, being resto mod it would certainly defeat keeping the theme of looking somewhat original, but no doubt would give mounting options.

Yes, the 7mm bolts that secure the bars, well mine currently remain 7s, but I may convert to 8s if need be.  What we have found, on EBay, are Honda 50 and clones Pitbike bar risers from China that can work.  Does require finding longer bolts though. I may simply find the bolts, get a few lengths, then fabricate risers from flat material.

Your setup certainly can be fine tuned.  Curious, when you stepped up to 8mm, did you install the HeliCoils for added strength, or was there another reason.

Edited November 24, 2018 by pmk

[b40rt]

7 hours ago, lineaway said:

 It does not matter how tall you are, foot peg and handlebar position is all the same. Take a look at Dougie Lampkin`s bikes, nothing done for his height. Your body has a  proportional relationship between wingspan and height. Have you ever heard of short people raising the pegs? What is funny is tall people are lazy when it comes to bending their legs. If they would, the advantage they have over short riders 

 This generalized makes no sense, twinshocks when new, did not all have identical bar / footrest positions.

SWM's came from the factory in 1980 with either Marzocci or Betor yokes, a difference of about 2". The Marzocci yoke was considered a better position (further forward) and was fitted by the likes of Martin Lampkin, but retaining the betor forks. In the 5/6 year period swm's were dominant the footrests moved dramatically down and back. This can easily be verified. 

 

[fourex]

21 minutes ago, pmk said:

Your setup certainly can be fine tuned.  Curious, when you stepped up to 8mm, did you install the HeliCoils for added strength, or was there another reason.

It was over 2 years ago when I did the mod on the Ossa and it has taken a back seat ever since due to other projects. I drilled and tapped them to 8mm and this appears to have worked fine but I didn't understand the benefits of a helicoil into alloy at the time.

The S3 mounts come std with the 8mm low profile socket head bolts.

[pmk]

1 hour ago, b40rt said:

 This generalized makes no sense, twinshocks when new, did not all have identical bar / footrest positions.

SWM's came from the factory in 1980 with either Marzocci or Betor yokes, a difference of about 2". The Marzocci yoke was considered a better position (further forward) and was fitted by the likes of Martin Lampkin, but retaining the betor forks. In the 5/6 year period swm's were dominant the footrests moved dramatically down and back. This can easily be verified. 

 

In regards to the yokes (tripleclamps), the 2” you mention, was that fork tube offset or bar position?  If bar position, was that 2” up or 2”” forward only with no height change?  I realize you said forward in the post.

Learning as much as possible.

Edited November 24, 2018 by pmk