For the moment, the day to day hack is an 07 Aprilia Pegaso Trail. Not the worlds most exciting bike but was a damned good urban commute machine. And, until Granny’s postal order comes through, I’m stuck with it
Now, despite the change from fashionable “off road” tyres to road tyres, this whole thing gets a tad unstable at 70 (ish) so the ultimate top speed is a bit academic.
I’ve sourced a supplier for a decent quality/price kit dropping the front sprocket by one tooth which should perk up the acceleration.
Couple of questions for opinions:
1: Should I do that?
2: Any blindingly obvious down side I’ve missed?
3: (I lied) Am I going to take a link out of the chain? I only ask as I’ll need to borrow a chain de riveter before I start the job if I have to. (Experimenting with a spring link for the re joint.)
I’ve dropped a tooth on the front on my 91 ( I think ) Pegaso.
Did not shorten the chain, just adjusted.
Did make a noticeable difference on acceleration but the old air cooled rotax really did start to run out of puff at 70mph.
I’ve heard tales of chain life being reduced as the chain has to turn through a tighter circle running round the smaller sprocket, but TBH I never noticed.
+1 in increased chain wear, better to add to the back
i added two to the rear and took on of in the front and now its…
OMG :w00t: hold on to your hats!!
def do it!
do it from the back sproacket first, and dotn forget you will probably need a speedo healer too.
Amazingly useful website to play with -1, +1, +3 etc…
http://www.gearingcommander.com/
If your speedo sensor is on the front/rear wheel then you’re fine.
But if your speedo sensor is through the transmission then a sproket change is going to throw your speed readings off.
If your speed readings are off so will your odometer miles & services eventually.
Thanks for the advice guys and good thinking about the speedo sensor. I don’t have a clue where that is so I’ll have to look in the parts book. I’ll do an RPM/speed check before and after as well.
Agreed, raising the toothage (apparently not a word, but you know what I mean) on the back is probably better but a silly price penalty. Pretty much made to order it seems. Also seems to need a longer chain so even more cost.
Thanks for the site link Alex Gold, I’ll have a browse asap. I’ve done the sums and it looks like a 6.bits % drop in gearing for the minus one on the front.
I’ll post when I’ve done the suck-it-and-see next weekend.
have dropped a tooth on all of my bikes, never had any obvious adverse chain wear myself. then again i also only wd40 my chains and they last for ages but apparently thats blasphemy also
should only make a couple of mph diff at the speeds the bike is capable of, not that much worse than over-reading speedos you normally get!
if you do decide to correct the speedo. then get a speedohealer from healtech… they even have an online calculator to help you calculate the % difference based on standard gearing vs new one.
i just went with actual (looking at a toyoya prius when i was next to it) vs indicated
Pan I thought that the only useful purpose served by the mile markers on the motorways was for checking speedometers. (Helps if you have a passenger to work the stopwatch.)
I know my speedo. is pretty optimistic so I’ll do initial checks with the rev counter match. Thanks for the info on the “seedohealer” Might yet be handy.
johnnybravo Shame on you for using WD40 when you could be using silly price “chain lube”. Don’t let people know that I also use WD40 for the weekly job with the occasional clean followed by chainsaw oil.
Might mend my ways and start using building industry silicone spray this time around though just to see if it works. Consider it a public service.
