Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[kensiko]

You didn't see bttf movies ?

[NoiseBoy]

Just change the sprocket man! If you don't like it you can change it back.

[krash7172]

This topic resurfaced so I thought I would post that I have not installed my sprocket. I'm concerned about the stock tires and I'm not sure if anyone knows how to code the speedometer for a 2014 SR.

[MichaelJohn]

This topic resurfaced so I thought I would post that I have not installed my sprocket. I'm concerned about the stock tires and I'm not sure if anyone knows how to code the speedometer for a 2014 SR.

As Doug S said earlier in the thread, I can't fathom wanting more torque than the bike already puts out. As a new SR owner I am blown away by the bike's acceleration on every ride - it is so quick that there are very few situations where I can actually go to the throttle-stop, and then only briefly. I have owned some very fast vehicles and have always wanted just a little more thrust - not with the Zero. It scares me as it is. But, different strokes. If you do the mod and it is noticeably quicker I would love to read a ride report. Are you targeting Veyron acceleration?

[krash7172]

Just because you got it doesn't mean you use it every time you go. Range and top speed isn't an issue for me. It's personal. The SR has no top end anyway. 100 mph is mid range. It's a low end beast.

[TheNorwegian]

I've never been able to get the front wheel off the ground on the Zero SR. I was thinking that a high gear torque would aid that. Of course the Zero already has a great amount of torque, but it also has a top speed way higher than I ever want to use. So to me this mod makes a lot of sense.

I would love to encourage someone who's up for it to give it a go.

krash7172 and biolife - you obviously are curious to how this would work. I say just do the mod, test it. Film it. If you don't like it (which I doubt), just put the stock gear back. And user dgh853, you're the track racing guy on the forum, you're curious and great at doing mods.

I would do it myself but it's winter here with snow - and my 2015 haven't arrived yet.

[TheNorwegian]

Just got an email from my dealer. Who tells me the cheif european technician for Zero says it's ok to change the gear. I can even order my new 2015 SR delivered with the higher torque gearing from the dealer.

I asked about details, I hope he comes back with more.

[krash7172]

You can always try the 28T sprocket. I would have ordered that if I knew it was an option when I purchased the bike.

[aaronzeromoto]

We don't recommend changing this sprocket on the Zero SR for two reasons.  First, the higher torque has resulted in broken belts for some customers. Second, your odometer and speedometer won't read correctly without further adjustment. I know of some customers that do this for racing purposes only but are willing to bear the extra costs that results because the issues it can cause are not covered by your warranty.

Regards,
aaronzeromoto

[evtricity]

I have recently changed to an equivalent high torque / low gear option by way of a chain drive running a 15 tooth front and 80 tooth rear. This is very close to the same gearing as a 25 tooth and 132 belt drive.

I had been told of the risk of belt snapping so the chain drive was the only safe option to my mind until Zero move to wider (and stronger belts).

So what's it like and will it wheelie?

The acceleration is a small but noticeable improvement over stock and the bike will wheelie in certain circumstances - uphill and sitting back on the seat it will come up a little around 40kph. Top speed is now about 137kph (85mph).

The Sava MC50 Racer 140/70 17 tire I'm running is certainly capable of handling the extra power in a straight line, whether there is  enough power to get real wheel slides when leaned over on the track I'm yet to test but I doubt it as the torque drops off from 3000rpm to 6000rpm (latter is max rpm). Also, 135kph on the track is way too slow for anything but a short tight race circuit so will likely switch back to the 185kph (58 toot rear sprocket) setup when I'm next at the track.

For those who are keen I would follow Zero's suggestion and not use the 25 tooth with the belt drive. I think the chain drive route is the way to go and gives more flexibility in gear selection. A friend of mine has a CNC machine and could make custom sprocket sizes to suit your needs - you'd need to replace the front sprocket with a taperlock setup or similar as we have done.

Dave

[krash7172]

Sweet Did you calibrate the speedo?

[evtricity]

Not yet, you need a custom cable that connects to the MBB (Main Bike Board) to make that change. I believe it can be done by your dealer if desired. I'm using a Garmin bicycle GPS to give me accurate speed readings ATM.

[NoiseBoy]

Do you need to buy 2 chains and link them together to get enough length?

[evtricity]

Do you need to buy 2 chains and link them together to get enough length?

One chain will be enough for 15 x 80 combination but it needs to be at least 135 links.

I used an RK 428SO chain with 136 links and I took out a pair of links to keep the wheelbase short. 136 links would work too but you'd need to pull the wheel back further.

I think you should consider the ZERO FX CHAIN KIT. If it matches the stock gearing on the FX then this is equivalent to the 25/132 combination people are looking at for the SR.

[rayivers]

That sprocket looks really nice! I've had good results using HD 428 chain on my ICE bikes, it's light and low-drag.

The FX chain kit (520) has 12T front / 65T rear sprockets, for a 5.42:1 ratio (about 2.6% lower than 25/132). I think they may have done this to minimize changes in RW torque and speedo readings when using knobbies, which are generally larger in diameter than the OEM low-profile IRC.

I've been looking at all-steel-wear-points chain options to get the front wheel up easier on my FX, and it seems the easiest route might be 530 chain, which has the same dimensions as ANSI #50.  Martin makes 1"-shaft 1" wide #50 front sprockets from 10T to 23T, and I believe both SuperSprox and Sidewinder make custom 530 hybrid rear sprockets up to 70T (I'm waiting to hear back from both). 

The '04-'15 KTM 85SX rear wheel appears to use an identical sprocket mounting setup to my FX (four M8 holes in 132mm dia. circle, 110mm center hole) which made spec'ing the custom sprockets a lot easier.

Ray