Honda CBR 250 Forum banner

41 - 51 of 51 Posts

·
Registered
Joined
·
40 Posts
Well I also tried harder settings on the rear shock at the very start, when I picked up the bike from the dealer, weighing 90 kg and this being a smallish bike, I presumed that on the lowest setting there would be way to much sag. So from the start I cranked the shock to the 5th or 6th setting. Terrible! The road are pretty bad here in Italy, full of holes and very uneven and so the ride was terrible.
Well I shall soon see if the 450$ was worth it for the YSS shock from tygaperformance.com. It seems to have a good deal of tunability. I am sure that it will not be anywhere near Ohlins quality but then neither is the price and for a 4200Euro bike, a 350Euro shock will do.
 

·
Registered
Joined
·
3,527 Posts
I measured my sag. I'm 165 pounds/ 75kg with my gear on. With the rear set on the lowest setting, I am getting 1.5 inches/ 38mm with me in the saddle and 40 pounds/ 18kg on my rack which is about the most weight I can envision carrying. That is 30% of the total travel so the spring rate is pretty close. I might ideally go down a few percent and then crank up the adjuster on a lighter spring a couple clicks if planning to travel with that much weight in full cases, but the stock rear spring is not that bad. We could use a better balance of the high speed compression to get rid of the chop over highway expansion joints.
The front measures really soft. With just me on the the bike laying on the tank in my normal highway position, the sag is 2.1 inches/ 53mm. And, if the total travel is supposed to be 4.1 inches, it doesn't feel it because at that point I can push the front end down hard enough to touch the bottom bumper though I have never felt it bottom on the road. I have never felt it wobble during top speed runs so the damping is ok for commuting. Heavier riders may benefit from the Bikers up adjusters and racers will want stiffer springs and damping in the front which might be as simple as more preload and heavier oil for those that want to save money.
 

·
Registered
Joined
·
3,527 Posts
High ratio

This bike's, like most sport bikes, rear shock has a very high ratio/ short stroke which makes the high speed flow rates that much more difficult to match to the low speed. The ratio looks to be as high as 4:1 as the shock has little more than an inch of travel to work with. Plus, any stiction is amplified 4x more than a 1:1 shock would transmit. The pricing is reasonable so it will be intersting to see what YSS will do for us in the way of direct support as they have acquired a merger with an Australian shock design company so English language won't be a barrier.
 

·
Registered
Joined
·
113 Posts
The YSS rear shock from Tyga Performance actually looks like it might be a worthwhile upgrade for half the price of the boutique shocks.
.
Y.S.S. - YSS Rear Gas Shock, CBR250R - Other Products
.
Maybe we can get them down a little more with some kind of group buy.
A group buy might be a possibility. Like all things, it will depend on the actual level of interest. If one of you want to head up a group buy - shoot me a PM. I have a few of the shocks on their way, and will have them up on the website when they arrive.

Bill
 

·
Registered
Joined
·
3,527 Posts
A group buy might be a possibility. Like all things, it will depend on the actual level of interest.
We will have to see how well they work. Unfortunately my days of riding are just about done for the next three months so I may not be able to do the advance testing on this one. I was lucky to get my new front sprocket on in time for one afternoon of testing and one round trip before the cold weather shut me down.
 

·
Registered
Joined
·
501 Posts
Discussion Starter #47
I weigh 90kg ad have not found the right setting yet for the rear shock. I personally think it is more a damping issue though. I would prefer a slightly faster moving shock.
I agree on this also. When pushing the rear of the bike down while in a front wheel chock, the rebound damping is very slow. But after an aggressive ride over rough road and everything is warmed up, the rebound is much faster. A lot of compromise going on with the damping in the rear shock, in addition to stiff spring. And a $4000 new bike is bound to be all about compromise.
 

·
Registered
Joined
·
29 Posts
I'm weighing 86 kg without gear, which is 190 lb and for my personal preferences the spring tension is way too hard.

Up to last week I drove with position 2 all the time because I'm driving with a passenger from time to time. But recently I set it to 1 (which I almost wasn't even able to do because of my big hands and my clumsiness maybe as well).

IMG_20200427_134350.jpg


Unfortunately it feels still too hard. I think it's great for pushing the bike to it's limits and fast cornering, but I use it more as a daily driver to commute and there for I find it too hard.

Our roads are not bad in general but in town I have a lot of these manholes which covers are often built in way too low.

3905978_artikeldetail-bild_1spjxj_vwDYla.jpg
 

·
Registered
Joined
·
1,828 Posts
I'm weighing 86 kg without gear, which is 190 lb and for my personal preferences the spring tension is way too hard.

Up to last week I drove with position 2 all the time because I'm driving with a passenger from time to time. But recently I set it to 1 (which I almost wasn't even able to do because of my big hands and my clumsiness maybe as well).

Unfortunately it feels still too hard. I think it's great for pushing the bike to it's limits and fast cornering, but I use it more as a daily driver to commute and there for I find it too hard.

Our roads are not bad in general but in town I have a lot of these manholes which covers are often built in way too low.
You have reduced the spring preload - but that doesn't change the spring rate. Reducing the preload changes "sag" but not the actual stiffness of the spring.

Only way to get softer suspension action would be to get a different spring/shock that is accurately set for your size and riding style - same with the front forks. You would want to balance a new fork spring rate to the same rate as the new rear spring rate.

I'm surprised that at 86 kg/190 lbs the spring would feel too stiff. Typically the spring rates are on the low side on most smaller cycles. Make sure all of the pivots are operating freely.
 

·
Registered
Joined
·
29 Posts
Driving on winding country roads it's fine but when driving over potholes, speed bumps or badly built in manholes in the city it feels too hard. But I also have no comparison to other motorbikes, I'm actually only riding the CBR, so maybe it's completely normal.

What do you mean exactly, the suspension doesn't get softer by changing it from 5 to 1?
Because that's what I understand from the description in my owners manual.

--- edit ---

I just found another thread in which people are complaining about the hard suspension. Seems like I just lowered my bike which is unfortunate because it was way too low already before. :LOL:

Link to thread:
https://www.cbr250.net/threads/2011-cbr250r-suspension-too-stiff.66249/
 

·
Registered
Joined
·
1,828 Posts
What you are dealing with isn't really stiffness - I'd say it's more compression damping. That's what determines how quickly the shock responds to sharp bumps.

The adjustments on the spring do not change the spring rate, just preload - effect how much the spring compresses initially when you sit on it (sag). Backing down the preload will allow the suspension to drop (sag) more when you sit on it and lower the ride height.

Preload article - Sonic Springs

From the article - "Preload is perhaps the most misunderstood facet of suspension tuning. Many people think that by adjusting preload that they are stiffening or softening their suspension. Nothing could be further from the truth. Adjusting preload does nothing to your spring rate. (technical explanation below). All it does is change your ride height and your sag."

Let's assume that we have a pair of fork springs, each with a rate of 50 lbs/inch. The pair then have a combined rate of 100 lbs/inch. That means that it takes 100 lbs. to compress the fork the first inch, another 100 lbs. for the second inch, (total of 200) and so on. Also assume that the bike and rider together place a 300 lb load on the front end. If the fork is assembled with zero preload then the springs will compress 3 inches and the fork will compress 3 inches total. How much additional force does it take to compress the next inch?? 100lbs. Now say we add an inch of preload. The first 100 lbs of bike weight don't cause the forks to move, the next 200 lbs. make it compress 2 inches. The spring though is still compressed 3 inches and it still takes 100 lbs of force to compress the next inch. "


Sag article - Sonic Springs
 
41 - 51 of 51 Posts
Top