motorcycle geometry

I'm looking at changing out the rear suspension on my bike. The stock size is 14.2in. but that size is way too expensive, the best price I've found anywhere is over $300 each. I've found several 13-13 1/2 inch shocks for under $200 a pair. My question is that if I go with shorter rear shocks how will that affect the performance and handling? My mechanic says that it will make my bike dangerous to ride but he's also a purist, if he can find an OEM part, he'll get it. He doesn't like thinking differently.

Is going with a shorter shock going to do more harm than good or not?

Damon

You may need to lower the front end and keep your preload dialed way high.

That much difference in height can lead to bottoming out issues.

What are you riding?


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83 nighthawk 650. I don't see a bottoming out issue because from the tire to the rear fender is at least 8 inches with me sitting on it. I know ~1/2 in. seems like nothing but I'd rather get my ducks in a row before just doing it

Front is pretty easy to lower by loosening the upper clamps on the forks and sliding the forks up a bit. I would measure from axle to a point on the frame above to see exactly how much the shorter shocks lower the rear then match that in the front. Put it on a stand to take the weight off the forks before starting. That should keep the geopmetry pretty much the same.

http://hagonshocksusa.com/HagApps4.htm

The Standard Shocks are available for your application and run $199...

If you lower the front via the triple clamps, again, watch for clearance.


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If they're standard, not upside down, that is.

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Would it be possible to build some sort of spacer approximately 3/4" connecting the shock upper mount to the shock mount on the frame. I thought I'd seen something like that on here a long time ago.

are the prices on this list for pairs or individual? This list is a touch confusing. Because $400 a pair is still out of my price range. And it looks like they'd be coming from Europe, which means extra shipping and tariff fees.

If you do not need the bike lowered, then I would leave it stock if at all possible. That way you do not run into cornering issues, and you do not have to modify your side stand.

If you do lower, just make sure the front is lowered the same amount as the rear.

Vikti said:

are the prices on this list for pairs or individual? This list is a touch confusing. Because $400 a pair is still out of my price range. And it looks like they'd be coming from Europe, which means extra shipping and tariff fees.

Click to expand...

I believe those are priced per pair, but you will need to e-mail them to confirm. I had Hagon build a shock for my Kawasaki 650R. They have a US distributor in California - http://hagonshocksusa.com/ and shipping was not an issue. Took a couple of weeks to get the shock in and once it arrived it turned out they had sent the wrong one. But in all reality it wasn't exactly there fault as there are two VERY similar model numbers in Kawasaki's line up and they sent the wrong one. They quickly corrected the issue on their dime and I have nothing but praise for them. They were GREAT to work with and I love the new shock.

This shows the price is per pair, but you still need to call or email to confirm...

http://www.hagonshocksusa.com/HagShocksPr.htm

While an inch+ change in free length is not inconsequential, the important thing is to know what the loaded height change is. If the new shock has a stiffer spring rate, it will sag less than the original and you may end up very near the same ride height as original.

For example: assuming your bike is 400lbs and with rider/gear/fuel is 650lbs. If the weight split is about 50/50, then there is about 325lbs on the rear axle.
If the factory spring rate is 75lbs/in, that would make the sag 325/(75x2)=2.16
But if the replacement spring rate is 125lb/in, the sag is 325/(125x2)=1.3
2.16-1.3=.86 which is actually more than the difference between the free length of the stock to replacement. There is some geometry lost in these rough calculation since the shocks on most modern bikes are at an angle and not completely vertical.
(all these number are notional and not representative of what you may or may not have)