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I'm surprised this thread isn't blowing up.
I just bought 2 2017 crf50's, both need stiffer springs for adult rider and I'm not seeing any info about the 2013 and newer chinese built frames except on this thread. None of the parts suppliers I have seen have mentioned anything except on tbolt, and I cant find any info about this TRC shock anyways so not too helpful other than for specifying the frame difference.


Why is there seemingly such a lack of info on this? Are all 50's after 2013 built with the same frames or only the China built ones? To my understanding they are all assembled in China from 2017 onward.
So it seems the 2017's (And any '13+ China built) have a shorter spring on them for the rear shock to accommodate the change in the frame. Does that mean the BBR stiffer spring wont fit on my shock? My spring measures 4.5 inches when I lift the rear tire off the ground, this one measures at 4.75 so I might be able to get it in but will it be too stiff after?


My plan was to just upgrade the spring with this one, now I'm considering just getting a spring/shock together but I'm having trouble finding any that were linked earlier in this thread. I snapped a pic my dirty frame, its about 1 3/4" wide at the lower part of the frame where the shock passes through, and about 2 1/8" at the top. Does anyone have a measurement on a pre 2013 frame? How different is it really? What is everyone running on their China built frames for adult riders? Not really wanting to change to a mx swing arm.
 

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No, the frame is different not the shock or spring. If you are just looking to change to a heavier spring BBR I don’t believe you will have a problem but double check the O.D. of the new spring before ordering.
 

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Yes I realize the frame is different but I thought the shock was different too to accommodate the change in frame. I didn’t know if the pre 2013 bikes had a spring that ran longer on the shock. Thanks for filling me in on that.
How much narrower are these frames then since 2013?
This Kitaco seems like the best fit, can’t find one for sale tho
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I was worried I’d be able to feel the spring rubbing when riding. Seems like my only real option right now is the FastAce BDA01that you mentioned earlier in this thread. Do you feel it rubbing while you ride? I feel like it’s going to ride better with a proper spring and shock combo instead of just the bbr spring.
 

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Beauty, that really isn't hitting it much at all. This week I'm ordering a bar kit, TB manual clutch, tall seat and this BDA01 shock. I'll post back here once I install the shock. Thanks for that video jamesfl
 

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Aside from the frame rub issue, another word of caution here when choosing a new rear shock.
The front and rear of bikes are balanced in a travel perspective from new, the front travel always is set to exceed the rear (or at least be the same in small travel situations). Same rule applies on hardtail mountain bikes (front has travel, rear none), that's why they are trailable. The rule is always have more travel in the front than the rear, but when replacing the rear shock you have commonly two options - exact same travel length, different spring ratio, or a longer travel shock with alternate spring ratio. The biggest issue I found is if you add a longer shock in the rear of a crf that gives more travel than the stock front (or an extended swingarm for that matter as the result is the same with more travel) , expect a woeful see-saw ride... you will notice straight away your lack of control in the front as the rear tracks you faster over terrain but the front fails to absorb the bumps equally. So my advice is purchase cautiously - choose shocks that have a similar travel length to existing, sure go firmer spring to deal with adult weight but only add in a longer travel shock when you are doing something like longer travel hydraulic forks up front. You really want to always keep the balance of more travel up front. Heads up I'm talking purely from my 51 years of experience with riding motor bikes .. I'm 59 and started riding when I was eight, have had a lot of suspension experience. This is just my take from experience on suspension upgrading, hope it assists everyone out there.
 

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Darrie, thanks for your input. The fast ace shock is the same length, and I believe the same travel, maybe another 1” but I’m not seeing that anywhere in the product description right now about longer travel. Maybe down the road I’ll have to get +1 forks if I find the bike see-saws or tracks poorly.
 

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Years ago I made a 110 shock fit inside the stock frame. I spread apart the subframe using a porta power and this:

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OK, so just like jamesfl said, the shock only fits with the spring adjustments at the top, and the spring rubs the frame a bit. I lubed the contact areas with grease to get rid of any noise. I found the new assembly to be a bit longer and the mounting points a bit narrower. I added a washer to the bottom mount to take up the slack, top was fine. And the preload was too stiff for me out of the box, I turned it down two full turns on the spring adjustment and softened the dampening. (170 Lb rider) Feels good and seems to have a fair amount of adjust-ability, wont get a chance to go for a ride for a few days tho. So for anyone wondering, this FastAce BDA01 is a good choice for 13+ crf50's.
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Suggest you get a fine hex key and take out the lube the rebound dampening adjustor screw shaft whilst new.
It's mild steel & has a nasty habit of rusting up easily.
 
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