Footpeg Location

[pmk]

Aftermarket footpeg location brackets and do it yourself footpeg relocating certainly is popular on vintage bikes currently used in competition.

In general, how or what criteria determines the best footpeg front to rear location?

Is the lowest possible position that kerps the fert safe best?

While researching this, one company mentioned that going rearward with footpeg mounts is not always a benefit, it can reduce weight on the front tire and creates steering issues.

Being specific, we will be modifying the setup on my riding buddies 72 OSSA MAR.  The internet has many photos of these machines with footpegs anywhere from stock to 50mm x 50mm down.

As a rider, he is 6’3” and about 200 pounds with gear on.

 

[turbofurball]

Best thing is to ride it and see if it feels cramped, most twinshock riders want a certain modicum of comfort that the original riders weren't worried about ... at 6'3 your chap may struggle.

My TY has a peg kit and benefits from it, though without the lengthened back swingarm it might have been a bit wheelie happy in it's current state of tune!  On the Cota I have a 1" lift on the handlebars and stock foot pegs with a little extra platform welded to give more surface area.

[section swept]

Main reason for altering the footrest position is to anable the rider to stand comfortably in an almost upright position. The original position if you look back at the professionals riding they were using their knees far more and were perched on the bike and could flick the bike from side to side quickly. They could also move their weight around front to back and also the foot rests being high compared to the new thinking were out of the way of rocks etc, most being designed to spring back and up unlike the new rests that tend to just swing up. The old rests were a bit bendy so a clout from a rock bent the rest rather than throw the rider off the bike. 

It is usual to position the rests down and back but no further down than the wheel spindle line of sight. If you drop a plumb line from the swing arm pivot this usually indicate a starting point for the new location. Note this does not work on all bikes so experimentation is needed. Another point to bear in mind is the fact that quite a lot of the old guard ie Miller, Peplow, Smith etc were not tall people, whereas Andrews was a large framed person, so a close study of works trials irons of the time may show up slight alterations not immediately obvious to the casual on looker.

When you have repositioned the footrests you are more likely to clobber your feet in tight sections, but with the broader platform and heavy serrations you have better confidence feet wise and a bit more control if you are a hoppiest or bouncer. Jiggling the bike about for best angle of attack!

The rule of thumb in earlier trials times was to keep the bike as upright as possible and use body weight transfer to steer the bike. Whereas the new thinking is to use balance and bike positioning to obtain the best steering and drive. 

Me, I prefer the original positions, but when you look at the latest trials machines there is only one place to position the rests, but then the geometry of the bike is totally different to an Ossa of 1972 or any other bike up to about 1989 ish.??

[lineaway]

 The foot pegs on the Ossa was fairly low. I would just get creative with the pegs, but I was an MAR lover.

 

[still trying]

high foot peg positions were (if I remember right) to help clear rocks and such. It also meant there was less bike between the riders legs allowing for more movement on the bike. These days the low seat height, suspension and narrowness of the bike takes care of this. If the pegs are lowered balance becomes a lot easier. It will also suit taller riders as they will be less cramped.

Moving the pegs forward or back moves the riders nominal position and as stated can affect steering or rear grip adversely. An inch either way probably wont cause handling issues, but will help with tuning the bike to your riding stance, physical size, e.t.c.

[pmk]

The mention of setting the height based on the axle centers is great info.  Easy to check, and guessing the MAR footpegs are above that reference line.

For whatever reason, this IPad is not accomplishing searches here, but I plan to keep gathering more info until we start cutting.

[lineaway]

I have always paid attention to foot peg location compared to swingarm spindle. It seems a lot of the old bikes were forward or even with the spindle. It has always seemed to me the bikes with the pegs behind the spindle seemed to handle better. The Ossa had them behind. In fact the link I posted the foot pegs were substantially moved, but dead even in relation to the stock location vs the spindle. So actually made the handling worse as the seat was now too tall to move around the bike. Those old bikes needed alot of body english to work. That is why I suggest a better peg.

 I had an 1982 Montesa Cota 200. It sat in the corner of my garage for 17 years until I started riding Vintage. That bike handled well. One day I compared it to my 1976 348. Major difference in peg location vs swingarm.

Edited November 23, 2018 by lineaway

[pmk]

This topic I found gave some insight into footpeg location front to rear.

 

[pmk]

Feetupfun, the topic I linked, do you recall the MAR you measured.  Maybe remember what year it was.  I ask, since your dimensions measured a wheelbase of 51.5”, same as mine, but doing the math based on swingarm length, I came up with 27.2% vs your 26.2%.  Any chance it was a typo mistake, or do you think they had different length swingarms while retaining the same wheelbase?

Even though you posted that info years ago, thanks, it was very insightful.

[pmk]

3 hours ago, lineaway said:

I have always paid attention to foot peg location compared to swingarm spindle. It seems a lot of the old bikes were forward or even with the spindle. It has always seemed to me the bikes with the pegs behind the spindle seemed to handle better. The Ossa had them behind. In fact the link I posted the foot pegs were substantially moved, but dead even in relation to the stock location vs the spindle. So actually made the handling worse as the seat was now too tall to move around the bike. Those old bikes needed alot of body english to work. That is why I suggest a better peg.

 I had an 1982 Montesa Cota 200. It sat in the corner of my garage for 17 years until I started riding Vintage. That bike handled well. One day I compared it to my 1976 348. Major difference in peg location vs swingarm.

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.  

[pmk]

Refrencing the linked topic.  In regards to the wheelbase and footpeg locations, has anyone got a reference to the front to rear weight bias on these vintage bikes.  Not critical, more curious about it.

[section swept]

7 hours ago, still trying said:

high foot peg positions were (if I remember right) to help clear rocks and such. It also meant there was less bike between the riders legs allowing for more movement on the bike. These days the low seat height, suspension and narrowness of the bike takes care of this. If the pegs are lowered balance becomes a lot easier. It will also suit taller riders as they will be less cramped.

Moving the pegs forward or back moves the riders nominal position and as stated can affect steering or rear grip adversely. An inch either way probably wont cause handling issues, but will help with tuning the bike to your riding stance, physical size, e.t.c.

What I said!

[feetupfun]

6 hours ago, pmk said:

Feetupfun, the topic I linked, do you recall the MAR you measured.  Maybe remember what year it was.  I ask, since your dimensions measured a wheelbase of 51.5”, same as mine, but doing the math based on swingarm length, I came up with 27.2% vs your 26.2%.  Any chance it was a typo mistake, or do you think they had different length swingarms while retaining the same wheelbase?

Even though you posted that info years ago, thanks, it was very insightful.

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

Edited November 23, 2018 by feetupfun

[feetupfun]

4 hours ago, pmk said:

Refrencing the linked topic.  In regards to the wheelbase and footpeg locations, has anyone got a reference to the front to rear weight bias on these vintage bikes.  Not critical, more curious about it.

What do you mean, "a reference"? My only memory of such things is magazine tests from the 1970s that measured the weights at each end without a rider, which is a fairly meaningless set of numbers on its own. The weight on each end with rider aboard is different for a given bike for riders of different weights. I'm interested in what you are seeking

[sherpa325]

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