Can i get a coil shock to fit or is it worth it???

stevekoz

Well as title suggest.

I run a fox rp2 with pro pedal on the rear of my bike for about 16 months. The bike is a rockrider 9.1, heavily modified spec, only the frame remains stock, as i've spent nearly the last 16 months building a bike i would consider is supremely suited to UK terrain.

Currently, I have her running 140mm fox 32 up front, at the rear i've kept standard 120mm travel system. But i've blown the rear shock twice now. I know that is alot to do with the fact i ride quite hard and am a heavy rider 240lbs with gear (CLYDE!). But i'm not losing any weight too soon and i still want to ride and keep the bike reliable.

The rear runs a 190 i2i shock with 50mm stroke, providing the total 120mm (4.7") of travel. So i've been thinking about changing out the rear shock again. Looking at differing air shocks and finally started looking at coil shocks this week.

But, after much digging, i can't find any posts/comments or opinions about running coil rear shocks on a relatively small travel xc/trail bike. I've seen coil shocks like the fox vanilla RC with the same i2i length, but i'm not too sure about the ratio's involved to get the right compression and stroke for the bike without adjusting the frame ratio's and limits. In fact i'm not sure it would be enough leverage to actually activate the travel?

Any comments would be appreciated as always guys. Recommendations for a strong shock. But i'm very interested in this idea of running a coil so if anyone runs one on what they'd consider a shorter travel bike then i'd be interested to know what set up you run, how you came to it, issues, recommendations, tips etc.

Cheers
Steve

cooldad

If the eye to eye and stroke is the same, you can get different springs to suit.

nicklouse

Steve what pressure are you running the fox at?

stevekoz

Air pressures - man, i've tweaked and changed loads to try and find a happy medium and honestly no joy. Some people i've spoken too say that it will take up to 300psi. My LBS said more like 260 and for my weight about 200psi +.

Fox's own wesbite recommended anything over 125psi. I've tried it at around 175psi for the last 6 months and it was ok, bottomed out on some medium drops but then i am 240lbs fully laden and i was pushing quite hard. It seems to get tough to put more than 200psi into it if im honest, so i've not tried rather than risk blowing it...ironically thats what has happened again for the 2nd time.

nicklouse

so what pressure to get the required sag?

the numbers mean nothing. until you find what you need to give the sag you want.

air is that simple add air to give the sag you want in your riding kit in normal riding position.

going to a spring in more complex as you need to work out what spring you need and then as you lose weight you will need to change springs.

but what i am trying to find out is what might be the issue.

poah

fox van RC will fit, I have one on my ghost

The Rookie

So how does that tell you it will fit an RR?

poah

The Rookie wrote:

So how does that tell you it will fit an RR?

OP says the frame has a shock mount i2i of 190mm with a 50mm stroke and looking at the frame design I can't see where the piggyback would foul the frame hence why I said it would fit.

stevekoz

In answer to your question, at 130psi i have a sag of about 22/23%, which i found bottomed out a lot. At 150psi that was more like 25/27% off the top of my head, its been a while since i've sat down and properly written out the calculations. 150psi is what i've generally been riding with and experimenting with a bit more here and there.

In regards to the Van RC fitting, i've seen a couple of Yeti sb66's with Van RC's and they are pretty much copy cat frames of the RR. I can't see there being an issue with clearance as long as it matches the 190 x 50 set up. But i have yet to try one so its all relative guess work till i actually (if i) buy one and fit it.

From what im reading though i still think that the main problem is my weight and thats my own doing. I'm a heavy guy, but i've lost nearly 4 stone in 24 months riding which i'm really happy about and on the right path. I get that as i lose more weight i'll have to change the springs, 20 quid a go 2nd hand isn't too much for me to contemplate spending. I get that the air shock if set up and running properly should be able to cope with pretty much any weight. But, i am just not finding that its working for me now. The coil shocks seem more suited to riders of heavier disposition. Which is why im thinking about it as an option.

nicklouse

Stevekoz wrote:

In answer to your question, at 130psi i have a sag of about 22/23%, which i found bottomed out a lot. At 150psi that was more like 25/27% off the top of my head, its been a while since i've sat down and properly written out the calculations. 150psi is what i've generally been riding with and experimenting with a bit more here and there.

ok it seems that you have things confused. as pressure goes up sag reduces. weather a measurement or a % and the pressures you mention are totally OK and you should not be having issues.

but i dont think we have the full story.

to a coil shock, using the info you have provided you need a 700lbs spring which you can now get (40 quid a time) good luck finding the correct ones used.

the piggy back on the new Vans might cause issues.

I would be trying to work out what caused the air shock to fail.

stevekoz

Hi, thanks for trying to help me get to the bottom of it. Its appreciated, but my maths is just cr*p. I've just got the figures muddled up in my head. I would say i've been using around the 25% area as sag on the shock. I could have course been setting it up wrong?! But i followed the relevant instructions to set sag.

As for the full story, not much else to tell really?? Not sure what you mean. No reason to hide anything?? Like i say 240lbs riding weight. Run the shock at around the 150psi more often then not, recently tried running it slighly higher see if it felt any better. But its now blown a seal. Not much else to say really. It's all down to my weight i think. I think i'm just too burly for the shock. May be it needs a full rebuild not just an aircan service? Maybe there is something wrong underlying that im not picking up doing an aircan service?? I don't know. But in which case, the cost of doing that, i could buy a 2nd hand coil shock and give that a go? I've seen springs second hand, yes i may struggle to always find the right one, but, may be its worth giving it a go. I'm not sure.

The Rookie

This is all meaningless unless you can work out the sag and set it right, pressure by itself means nothing.

If you are bottoming it out, that is as likely to be causing you as many issues as the pressures, so I'd be looking at
1/ Setting the sag RIGHT.
2/ Compression damping (which should be higher to match the spring rate)
3/ Volume reducers in the can to increase the ramp up of the pressure in bump.
In that order.

cooldad

Just to clarify - you did an aircan service, then it blew a seal?

stevekoz

In answer to your question cooldad, no, it hadn't been serviced beforehand, well it had, but it was like 14 months odd previously, so a bit overdue. But not by much given i've ridden less this year due to work.

stevekoz

I would say that i've been running it at about 25-30% of total travel. I can't go back and measure it now as it broken so no way of doing the calculation. I'd have to get it fixed and reset up and then i could tell you exact figures/%'s & measurements. But right now i can't. I don't memorise them, i fit and forget unless its not working. And up till now its been fine.

The bottoming out happened a couple of times at places i've not ridden before, which are far more technical than i'd normally ride. Combined with my heavy ass dropping onto the bike, i'm not surprised it used all of the available travel!

I could get the shock set up as you suggest, but combined with a full rebuild, cost of tuning it to my weight, bike and riding style, i could buy a coil shock and compare if that is any better. Which is why i asked the original question.

The Rookie wrote:

This is all meaningless unless you can work out the sag and set it right, pressure by itself means nothing.

If you are bottoming it out, that is as likely to be causing you as many issues as the pressures, so I'd be looking at
1/ Setting the sag RIGHT.
2/ Compression damping (which should be higher to match the spring rate)
3/ Volume reducers in the can to increase the ramp up of the pressure in bump.
In that order.

The Rookie

Nothing you say suggests it should fail, the fact it was fine for 14 months supports this, maybe something got in and damaged the metal or seal, or something else changed (such as a change in damping or a change in air pressure).

As it happens a friend had his collapse at Cannock (Spesh stumpy), pumped it up and it never did it again ever......can't recall the make/model of shock he was running.

I'd do a DIY overhall, checking everything thoroughly.

poah

nicklouse wrote:

to a coil shock, using the info you have provided you need a 700lbs spring which you can now get (40 quid a time) good luck finding the correct ones used.

the piggy back on the new Vans might cause issues.

I would be trying to work out what caused the air shock to fail.

shouldn't have any issues with the piggyback on the frame

stevekoz

No you arent wrong. I dont know why either. Either a faulty part maybe?? Or the only difference was it was the first time its been properly muddy so the whole bike, shock included, got filthy. So maybe something got inside.

It will get stripped n fixed. See what there is to see. Try n figure out why.

In the interim ive got a couple of coil shocks in view that would be worth the money just to see if I like them any better than air.

Or as its nearly Xmas go the whole hog n buy a new bike. Sure wife would u understand. Ha!

poah

I'll be selling my pushed van RC as soon as my new shock arrives if you are interested

stevekoz

Be interested yeah. Let me have some details. Cheers