Gents,

I've noticed on the bultaco brochures (on Todotrial website) that the model series 124 & 150 have 1315mm wheelbase listed as opposed to 1330mm for earlier Sherpas.

Can anybody tell me:

1) is that true - ie did they really have shorter wheelbase?

2) if so what was changed from previous models (M91, M80 etc)? Was it shorter swingarm, steeper rake, less offset on the triple-clamps or what?

There is a bit of an explanation on todotrial, but its in spanish & I can't read spanish & it doesn't make any sense attempting to translate with my spanish dictionary or with google translation.

Can anyone translate: "gracias a un menor avance de horquilla"

Any help greatly appreciated

Edited October 16, 201015 yr by JC2

Can anyone translate: "gracias a un menor avance de horquilla"

Any help greatly appreciated

I think it means, "Does 15mm make an difference?"

I've just been comparing my 125 to my 49 late model 2.2, I think they call it, same frame as a 80 I think similar dimensions to a early 91/92.

The later 91/92 may be the same frame as 124/125 I'm not sure but they look the same without running a tape measure over them.

Anyway the swingarm is the same length roughly 410mm centre of pivot to end of swingarm, where they get the shortened wheelbase from is that the swingarm is mounted further towards the front.

If you look at the upright tube rear engine mount you will notice the later model is concaved a bit for the swingarm where as the earlier ones miss it without the concave so I think they just shortened the main frame dimension. The swingarm pivot to the rear of the frame is the same measurement.

That would make the rake of the frame the same I think, just a shortened wheelbase.

I measured my bikes the other day trying to work out why the 49 seemed to feel better (to me) both have 360mm betor shocks and the 49 steers beautifully the 125 is a bit twitchy I now think its shorter frame with the the 360 shocks steepen the rake a bit too much and maybe would better suit 340 or maybe 350 length shocks,(the originals measure 335 on the 125 and 325 for the 49)

I find the M92 handles completely differently from the M49. The M49 is very stable and steers slow. I can't imagine their geometry shares much.

gracias = thanks horquilla = forks avance =front? or advance?

Thanks for your responses guys. If anybody's got any more input, I'm still listening

I think you nailed it MRB. On a little more research it seems the change in pivot point actually happened from the M80 to M91 models - it just didn't make the brochures till the M124 models.

(The same happened w the pursang brochures when they shortened the wheelbase on the M103 Mk6 but the brochures didn't change till the M135 Mk8)

The spanish on the SherpaT (M124/5) brochure I believe can be translated: "thanks to a small advance in the fork" (meaning rear fork, ie swingarm)