If you race in the UK, then you have probably already seen Jim or his van in the pits tweaking and tuning riders suspension. Based in Shrewsbury; he offers servicing, custom tuning and data logging; a service that quite surprisingly no one else is really offering in the UK. We hear no end of axle paths, leverage ratios, high and low speed compression/rebound, and more marketing mumbo jumbo than you can shake a stick at and with prices for mid level DH bikes coming in around £3500 and quite easily reaching in excess of £5k+, the big question remains of how do we properly set these machines up to the job they were designed to do? Trial and error?More than likely, but in the pursuit of speed riders are experimenting with cutting tyres and throwing even more money at expensive setups, but are our current bikes perfect for us, or can we get a little bit extra out of our bikes with some help from an expert? That is where Jim from J-Tech comes in…

Emyr Davies at the 2011 Caersws BDS - Photo: Callum T

Words: Henry Marsh

Photos: Callum Biggin & J-Tech

Hi Jim, first off I’ll give you a chance to introduce yourself, who are you and where are you from?

– I’m owner of J-TECH which is based near Shrewsbury in Shropshire.

You run J-tech Suspension, what does an average day hold for you?

– Generally it’ll start with setting out tasks for the day, responding to emails, and processing online orders and bookings, then straight into servicing and tuning work whilst taking calls and responding to emails between jobs. Come late afternoon, make sure everything is packaged up ready to go out and once the courier has come it’s all about getting everything ready for the next day. Sounds boring, but it’s cool as each job is different – each one is treated individually and tailored to the customers’ needs.

How and why did you get into Suspension tuning? Have you always been tinkering?

– As soon as I could afford suspension I was tuning it! My first suspension fork was a Suntour Dual Crown fork which was just spring and elastomer. I was 14/15 when I got it, it was like a pogo stick! So I set about making a basic damper for it using the lathes and milling machine at school in my dinner hours. I’ve been making all sorts out of stuff out of Lego Technic since the age of 8; enough said!

What do you ride yourself? Any sneaky custom modifications?

– At present I have a Specialized Stumpjumper FSR that’s got a RS Monarch RT3 and RS Sektor fitted to it. The Sektor has a handmade damper fitted, which I’m testing a few theories on, and the Monarch has a new shim stack configuration I’m experimenting with.

Is that your perfect bike? Is there anything you would like to do in the future?

– I don’t know if there is such a bike, but I can say that it’s a very good all-rounder.  It’ll have plenty of different forks and shocks on there for testing and development.

You now sell a custom damper, upgrading Boxxer Race forks. What does this help you offer over the standard unit?

– The Boxxer Damper offers a giant leap ahead in performance over the standard Race/RC damper. Using extensive valving for both compression and rebound, each damper is built to suit the customer. It offers far superior damping control giving better stability and much more grip.

The sheer amount of adjustability available to riders these days is staggering, do you feel things have gone too far? Your own damper only has an external low speed adjuster and rebound.

– I don’t think it has gone too far, but I do think people need to understand what the adjusters do! Having lots of adjustment is great, as long as you know what to do with it, and it’s not a ‘black art’, it’s common sense and a bit of understanding. My Damper only has those adjustments because the rest is already set up for you, as each damper is built to suit the rider. The low speed compression and rebound adjuster just offer a little fine tuning within a usable range.

Do you think the CCDB deserves its pedestal as the ultimate rear shock? Can other shocks be tuned to compete?

– The CCDB is a very good shock, I’ve yet to tune any other shock to create such a good damping curve. It’s the most consistent and tunable shock I’ve tested.

The big question: Boxxers or 40s?

– I think 40’s have the edge on quality, chassis stability and damping performance. The latest 40’s are very good forks.

Fox now offer their Kashima coating on Forks and Shocks, and BlackBox riders have been riding DLC forks for a while. How much of a difference do you think this makes? Or is it marketing hype to get us to buy more forks.

– It’s difficult to quantify the difference, but there is a difference. The coatings decrease friction which in turn reduces shaft temperatures and increases response. In simple terms – you get a smoother and more consistent shock/fork.

How big a difference do seals make? Enduro have been offering after-market seals for a while now and Fox have just worked with SKF on a new low friction seal. Should riders treat seals as something to upgrade? Or just a wear and tear part?

– They can make a big difference to response. For emample, the new SKF Fox seals have much less friction than the old standard seals and so increase the response of the fork. So definitely an upgrade.

So far I’ve only talked about RS and Fox, but there are plenty of other fork manufacturers out there; Marzocchi, Manitou, White Bros, Suntour to name but a few. Why do these companies seem to be dominating the market so much?

– There are many reasons, but I think the biggest contributing factor is what the top riders are using! Of course, they have the most developed products which goes hand in hand with having the top riders using them, so it’s not a bad thing.

You offer a data logging service, do you think most riders struggle setting up their bikes?

– Some riders can set their bikes up very well, but there are only a handful of riders that can do this that I know of! Even then, it’s not necessarily balanced to the click. Data logging takes away all the guessing – simply, it tells you exactly what the bike is doing, calculated adjustments are made and tested.

How do you go about setting up a shock for an individual? What factors do you have to consider?

– The main factors to consider are riding weight (that’s with all kit on), leverage ratio and riding type/style. This info along with data acquired from data logging and dyno testing are applied to get the shock tuned as close as possible for the rider. However, no two people ride the same, so the only way of perfectly dialling in the shock is to do a Data Logging Day.

Jtech's dyno and extremely tidy work bench and a Lapierre getting set up for some data logging.

What tips would you give someone for looking after their suspension, to keep it working as it should?

– Keep it clean, keep seals and shafts/stanchions lubed with silicone spray and service regularly within the Manufacturers guidelines. If your suspension starts to feel different, don’t adjust it or change spring to supple it up – get it serviced!

Should riders be using Fork Juice or any other similar lube?

– Every rider should be using a silicone based spray lube, Fork Juice is just the job. Seals and shafts/stanchions should be sprayed after every ride.

One thing that always confuses me is high and low speed compression/rebound. As Albert Einstein said “If you can’t explain it to a six year old, you don’t understand it yourself” – how would you explain high and low to a 6 year old?

– Not sure if a 6 year old will get it, but here goes – It’s not about how fast you are going, but how fast your suspension has to move. For example, imagine the country of France scaled down as test track for a bike which can only travel at one speed. You start off on the east coast and it’s all flat and rolling, like a BMX track, the suspension is only ever moving in slow movements, these movements can be controlled by low speed damping adjustment. Then you hit the Alps and boom, your suspension has to compress really fast to take the impact, these movements are high speed movements and can be controlled by high speed damping adjustment.

Lots of manufacturers are putting a lot of time into air springs. The DHX Air was snubbed by a lot of riders, but the Vivid Air and CCDB Air are set to change this. Do you think air has a place in DH? Or should we stick to springs?

– Personally, I think you can’t beat the performance, consistency and reliability of a coil spring. The ease of adjustability of air springs is great, but compression ratios and temperature change are always going to be a problem for air shocks. The Vivid Air and CCDB Air are better, but only due to damper technology and the twin tube designs helping to keep the shock cooler.

Thrust bearings have been the hot topic of conversation amongst a lot of keyboard warriors on forums recently. They are being used in other sports, and the concept seems quite simple. Do they work in the real world?

– In a word, yes. They make your shock or fork react faster, due to reduced friction, increasing grip. They will effectively reduce the spring rate as the spring is not winding up on itself, so go for a slightly harder spring than recommended.

You help support quite a few riders, and have been involved in the race scene for a while, how important is racing to you and the progression of the sport?

– Racing is very important – people wouldn’t be too bothered about going faster without racing would they? I know racing isn’t everyone’s cup of tea, but it’s where things are developed and also promoted. Top riders help develop products and then the customer gets to benefit from that development, so it’s crucial for the progression of the sport. Enduro racing is going to spring up some interesting new developments.

Team Rider Perry Gardener in Linderets

Finally, what does the future hold for J-tech?

J-TECH will be forging on, increasing the number of brands available and getting more and more data to help customers get more from their suspension. More J-TECH designed products will be springing up in the future – watch this space…

For more information, please check out J-Tech Suspension.

Comments

comments

TAGS