Supermoto suspension/setup

[spirit crusher]

Hi guys,

read already a lot in this forum, but now looking for some basic supermoto stuff and advanced.I am from Belgium and have been riding last year on the karting track of Francorchamps with the following setup

Pitster Pro X2R
DNM rear shock 275 mm
Standard SM rims 10" with Dunlop TTGP92
Standard front forks with adjustable inbound & rebound.
GPX 140 Engine correct gearing for the track.

Recently went over to 12" with CST slicks ( 100/80 front and 120/90 back )because I had the feeling that I was getting to the limit of what the 10" ttGP combo could reach and wanted some more stability at higher speeds/cornering. Also set the rear suspension to SM setting ( around 30 mm rider sag,before it was set to like only 5 mm, way too hard ) ,and front suspension a bit harder than before,was a bit soft before.


Yesterday first day on the track with the new setup, and not a real succes. Made a nice slide in a fast right turn into the gravel, and also a lot of instability at other higher speed 90° corners.
In general I had the feeling I could not go as deep as all the rest ( actually always ) The corner I feel was the first time I was really trying to follow a friend, which I could easily beat with the previous setup, and made an immediately slide like I was running out of tyre and too much leaning angle.
For some reason I have a lot of vibrations during high speed corners, kind of shattering at my front fork. So I think the mean reason for all this not being able to go so deep and fast in corners, and steer easily is because of the front end.

So now the big question is, are these original pitster pro forks not good enough for SM riding ( too soft ? ) ? I have personally the feeling that any adjustment to the dampening does very few to the reaction of the bike on track.

And what would be a good upgrade for track riding only. I have seen a fast-ace fork set for sale here, but want to hear first from you guys what do you think ?
http://www.kapaza.be/nl/motoronderde...e-93295351.htm

They are 660 mm long , but no further info.

Thanks a lot !

[Dangle_kt]

Just to clarify a few points:

You used to run tt92gp tyres, and you went to CST slicks?

You used to have a firm rear, and soft forks, and now you have softer rear and firmer forks?

First of all, the change in wheel size will help stability, but the CST tyres are not very good, and over heat easily. Combine that with the fact they are about 5 years old now, and you are always going to have problems.

1st thing to do is take them off, and get 12" tt92gp tyres or PMT tyres. Running too soft a compound leads to front end slides and poor grip/crashes...I know because I nearly crashed at the weekend when my front PMT R slick overheated and very nearly dumped me on my face during qualifying.

Next, you need to set your suspension as a combined unit - not front and rear separate. DNM and 2 way adj front forks are more than capable of getting good times in, them problem is your making too many changes at once.

So first

Get good tyres, set them to 18psi Front and Rear. and set your suspension to base settings.

Then ride

Then make one change

Then ride

and repeat until you can tell what is going on.

only once you have made lots of subtle changes should you look to swap out suspension.

[spirit crusher]

You used to have a firm rear, and soft forks, and now you have softer rear and firmer forks? --> Yes. The pre-tension on the rear shock was set extremely hard by previous owner, like less than 5 mm rider sag.
Front forks I did not change a lot.

Here some more questions now :

- You mention PMT or Dunlop's, I assume the difference is a lot than with these CST's ? I read a lot about them, but did not know they stopped production and are at least 5 years old.
The overheating problem you mention, I doubt it. The temperature here on monday at the track was around 6 or 7 degrees max with no sun, and tyres never felt too warm after a session. I rode with a 22 psi pressure.

- I currently have the combo of 2.15 rims in the front and 3.00 at the back. What kind of tyre size do you guys advise ? Same front and back ?
I found these sava's softs, and after reading on this forum, the real battle is between sava and PMT always :

https://www.allwheels.nl/fiets-onder...scardeddefault

I think this is the sava slick everybody is talking about right ?


- I will also put my tyre pressure even lower than , I though 22 psi was already low, but ok.

- Regarding suspension, I have indeed tried to balance things. But for some reason it is hard to judge. The travel on the front forks seems so much longer than the rear suspension. I have rider sag around 30mm. But always have the feeling that the back is relatively hard compared to any setup in the front ( a lot of dampening or soft... ).
Any thoughts on this ? Fast-ace forks might be a better base to start from ?

Thanks !

[Dangle_kt]

Originally Posted by spirit crusher

You used to have a firm rear, and soft forks, and now you have softer rear and firmer forks? --> Yes. The pre-tension on the rear shock was set extremely hard by previous owner, like less than 5 mm rider sag.
Front forks I did not change a lot.

Here some more questions now :

- You mention PMT or Dunlop's, I assume the difference is a lot than with these CST's ? I read a lot about them, but did not know they stopped production and are at least 5 years old.
The overheating problem you mention, I doubt it. The temperature here on monday at the track was around 6 or 7 degrees max with no sun, and tyres never felt too warm after a session. I rode with a 22 psi pressure.

- I currently have the combo of 2.15 rims in the front and 3.00 at the back. What kind of tyre size do you guys advise ? Same front and back ?
I found these sava's softs, and after reading on this forum, the real battle is between sava and PMT always :

https://www.allwheels.nl/fiets-onder...scardeddefault

I think this is the sava slick everybody is talking about right ?


- I will also put my tyre pressure even lower than , I though 22 psi was already low, but ok.

- Regarding suspension, I have indeed tried to balance things. But for some reason it is hard to judge. The travel on the front forks seems so much longer than the rear suspension. I have rider sag around 30mm. But always have the feeling that the back is relatively hard compared to any setup in the front ( a lot of dampening or soft... ).
Any thoughts on this ? Fast-ace forks might be a better base to start from ?

Thanks !

To be honest, if you go round the paddock at a UK pit bike supermoto race and 90% of the field are running PMT tyres, which are very good, and a handful are starting to try the dunlops which also seems excellent.

Savas are OK, but it seems the compound isn't as soft - which leads to poor grip in low temp/damp conditions. It did used to be sava all the way, then PMT came along and now dunlop are back to making 12" tyres - and in my opinion the savas haven't kept up with the changes.

22psi is pretty high, is that set cold or hot? I run around 15-16 psi cold, which goes up to about 18 or 19psi when the tyre is working.

The wheels I run are smaller than yours, well the front is the same but I think my rear tyres are 2.5, though I know some people prefer the wider wheels.

[spirit crusher]

- 22psi was cold tyre pressure.

- Regarding PMT, this was a list I found :

12" Tyres :
Soft slick 100/90/12
Soft slick 120/80/12
Soft Blackfire 100/90/12
Soft Blackfire 120/80/12
Super Soft Slick 100/90/12
Super Soft Slick 120/80/12
Super soft Blackfire 100/90/12
Super soft Blackfire 120/80/12
R Slick 100/90/12
R Slick 120/80/12
R Blackfire 100/90/12
R Blackfire 120/80/12

So there is a loooot of choice I see the blackfire still have some thread, others ar just slick. Since I only go for a few trackdays when it's dry outside, I don't think I need blackfire ( correct me if I'm wrong ).

I would just go for the soft slick in the front 2.15 rim ( 100/90/12). Same type on the back, but doubting about size Would 100/90/12 work on a 3" rim ? Or would that just give a strange " stretch " to the tire and make it more flat ?

- Any thoughts on my suspension questions ?

[Dangle_kt]

Unless you are running in conditions below 7 degrees C I suggest you run PMT S but I'm not sure if they are soft or super soft on your list, the side of the tyre has R or S (or I saw an M for the first time last week) - R is basically the same compound as the rain tyre, but a slick, which means it overheats in temps over 7 degrees, and wears quickly, but will grip even in the damp (as long as its not too damp to need tread pattern).

S is for normal riding above 7 degrees and is a great tyre.

Personally I run blackfires, but slicks would work as well as the compound is the same.

So bascially, if you are a fair weather rider during summer you want PMT S compound Slicks.

Contact the seller to see what S compound maps to in your list.

The rear tyre should run a 120/80 - I;ve seen lots run that size fine on a 3" rear. Some people like the slightly flater profile it creates. personally I prefer a 2.5 rear, but its all good.

I think I;ve answered the questions on suspension - sort the tyres, then go and play till you are happier.