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PostPosted: Sun Oct 06, 2013 8:16 pm 
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Joined: Sat Jul 18, 2009 8:52 pm
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Location: Costa-del-Oldham
good luck with the build, i love these bikes..


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PostPosted: Mon Oct 07, 2013 11:01 pm 
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Joined: Sat Jan 22, 2011 11:22 pm
Posts: 358
Location: London
Thanks guys, much appreciated.

More updates coming soon, so long as the wife leaves me a day or two free to strip this thing down properly...

I took it for a spin around Richmond Park yesterday. That front end is a little odd at first, it does things you don't expect, whilst not doing a lot of things you do expect. Un-learning years of telescopic fork foibles is going to take some doing...

I've decided the Hope / Mavic wheels fitted as standard to the PRST-4, whilst delightfully light in weight and stiff in construction, are a little to "conventional" for this bizarre frame. It's currently wearing my 24 spoke Mavic Crossmax ST's which go some way to redress the balance, but a set of Crank Brothers wheels are going on it soon.


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PostPosted: Thu Oct 17, 2013 6:40 pm 
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Joined: Sat Jan 22, 2011 11:22 pm
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Location: London
Spare time to work on any of the bikes has been non-existent for the last fortnight, but today a set of wheels and tubeless tyres arrived, so naturally, they had to go on... I think they suit it rather well...

Image

The full stripdown will happen over the course of the winter, but for the moment what little time I have is being spent on a bike that's neither conventional or retro, but a 2004ish felt hard tail that's being converted to a crank drive electric bike to tackle a 30 mile daily towpath commute. Should save me a fortune in petrol!


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PostPosted: Wed Oct 23, 2013 11:39 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
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Joined: Fri Sep 05, 2008 6:36 pm
Posts: 4950
Location: Edinburgh
Hi,
Will be following this thread........

I have just picked up a PRST1 from a character that had it advertised on Gumtree.
A bit late tonight to start tinkering & stripping but something to
keep me entertained after almost a year away from the site :shock:

Cheers

GC


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PostPosted: Mon Nov 11, 2013 10:15 pm 
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Joined: Sat Jan 22, 2011 11:22 pm
Posts: 358
Location: London
The quest to modernise the Whyte goes on... Currently it's in several bits scattered across my workplace and my home, much to wife's extreme annoyance... :oops:

Still, it's all going well. The initial test rides revealed a suspension system that is surprising to say the least. The front end is as weird as hell and is going to take some getting used to, but it's really capable. It does dive a bit more than expected under braking though... The bike predates the widespread introduction of Fox's platform damping technology, so I've picked up an RP3 originally fitted to a quad link Marin (which shares the same rear end as the Whyte PRST-4, so the damping tune should work straight out of the box), and fitted it with Jon Whyte's upgraded bearing based bushes at one end, and an Igus low friction bush at the other. TFTuned have given it a once over to ensure its in tip top condition. The front end has acquired a Fox RP23, fitted with the same bushings. The RP23 has a wider range of compression damping tunes than the RP3, so I'm hoping that somewhere in its box of tricks it contains a tune that will suit the oddball front end of the PRST. If not, then it'll go back to the guys at TFTuned to be set up with the PRST in mind.

The carbon monkey lite riser bars have gone in the parts bin, along with a set of Hope mini's, the original XT rear mech, two 165mm Fox Float R shocks, a set of Hope / Mavic wheels, and various other odds and sods. Parts for the PRST are thin on the ground, but I've managed to acquire several spares, including a set of "Big Gripper" bobbins...

The big gripper is a revelation in simplicity, you can change out a set of wheels with a speed that's really only rivalled by the Red Bull F1 team on a Vettel pitstop. Every bike should have them.


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PostPosted: Wed Nov 13, 2013 8:26 pm 
Dirt Disciple

Joined: Tue Sep 17, 2013 7:06 pm
Posts: 46
Are you interested in selling the Monkeylites?


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PostPosted: Wed Nov 13, 2013 8:36 pm 
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Joined: Sat Jan 22, 2011 11:22 pm
Posts: 358
Location: London
Possibly...

The PRST has a reputation for having a rather high bar position, due to the clearance needed for the suspension movement, lots of owners fit flat bars, or a 24" front wheel, or even upside down riser bars to get a more "racey" riding position. This all makes the decision to fit risers a slightly odd one, and is the reason that I've acquired some very shiny carbon Bontrager flat bars. Once I have the suspension dialled in I'll take it for a lengthy ride and try to get everything set up so it's comfortable. If everything works as I hope it will, then yes, the monkeylites will probably go.


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PostPosted: Tue Dec 10, 2013 2:35 am 
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Joined: Tue Dec 10, 2013 2:03 am
Posts: 5
Hi Grant! I bought the Fox shocks you put on Ebay last week.

I've owned my PRST-4 from new, it was on the ATB sales website, and I think that it might have been the last one ever made. It has the later tubular front forks, and Deore groupset, but the purchasing process and initial running in mileage went far from smoothly.

The bike was delivered to me in a box, with the wheels out, but it was apparent from the start that the front wheel offset was wrong, as the central rolling axis of the front wheel didn't match where the centre of the spherical bearing was, so the forks and wheel were dispatched back to ATB sales, and a few days later replacements arrived.

After only a few road miles, the spherical bearing failed. The outer aluminium ring stayed put in the front wishbone, and the bronze bush, and spherical part moved upwards, wrecking the top hat, and allowing the wishbone to wear on the fork. Grrr.

At this point, I realised that this bike had obviously been thrown together as a 'demo' bike, and a full stripdown commenced, just to make sure there weren't any more nasties lurking. I gave up on ATB sales, as they never answered the phone, and when they did, claimed that there was never a problem ever with any of their bikes!

On re-assembly, the Hope minis were binding up, because the disc to pad clearance relied on the thickness of paint on the fork bottoms, and after having been apart a couple of times, this disappeared, leaving the front brake binding on when it got warm.

I'm sure that there were a few more things, but fortunately, I'm an ex engineer (once an engineer... etc.) so gradually, all issues were sorted out. Fortunately (again!) I'm an enthusiast for engineering oddity, so stuck with the bike, because I had always wanted one, from the first time I saw one back in the day at Scotby Cycles in Carlisle.

I have no doubt that had I paid full price for mine, my patience would have worn thin, and I would have returned the lot to ATB sales. They are a great design, some might say a classic, but marred with shocking build quality, and some unfortunate choices for the minor components, which spoil the whole. But, persevere, and you will find something with a very different look, and charm by the bucket load.

Unfortunately, I don't think that I'm typical of the sort of person who bought them, and the got (and deserved) a poor reputation, they obvously cost a boat load of cash to build, and in looking so left field and oddball, the market was never going to be that large. By the time I bought mine, I think that all the folks who were going to buy one, had done so by then, and the old stock had been hanging around at ATB sales, who just wanted rid. I bought mine, new for £1000.


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PostPosted: Tue Dec 10, 2013 11:05 pm 
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Joined: Sat Jan 22, 2011 11:22 pm
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Hello there.

Hope the shocks meet your expectations?

Sounds like there were a few quality issues there, although, to be fair, bikes like this would usually pass through the hands of a bicycle mechanic for set up and fettling before delivery to the end user, adjusting things like brakes (spot facing the mounts and use of proper shims is the only way to ensure proper alignment on the old IS mounts, post mounts are far better in this respect).

Still, at least you ended up with a decent bike in the end, although your T-four tubular fork is certainly an oddity. They were used with the entry level JW-4 which was sold in parallel to the PRST-4. They offer the same main frame, geometry, and general design as the pricier PRST-4, but had cheaper drivetrain, shocks, wheels and other odds and sods, and they did without the "Big Gripper" dropouts at front and rear, substituting standard Quick Release dropouts instead. You can see why they employed a tubular fork, the welded monocoque fork on the PRST looks like an expensive and time consuming piece to fabricate.

The JW / PRST bikes do seem to appeal to those with an engineering background. It must be the mechanical purity in the design. Nothing extraneous, everything there for a purpose. Some say its ugly, I say it looks "right".

I'm afraid that whilst your claim to "Last PRST built" may once have been true, I was talking with a chap at ATB yesterday who revealed that only a couple of months ago he pieced together the final PRST-4 from a few bits they still had, so he could display it on a trade stand in Taiwan.

ATB sales are an oddity in themselves. They never answer emails, but if you phone them they are always helpful. It can take time to get to the right person though, I get the impression that its a very small, very busy team there. They're currently ploughing every bit of time they have into the 2015 range of Whyte bikes. Having recently parted company with Marin in the USA, they can no longer rely on Marin sales to buoy them up. On the plus side, it means they have a little more freedom to explore new ideas, so perhaps we haven't seen the last of the likes of the Preston after all.


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PostPosted: Tue Dec 10, 2013 11:26 pm 
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Joined: Tue Dec 10, 2013 2:03 am
Posts: 5
Hi Grant,

Yes, I can report that the shocks are everything I hoped for from your discription on Ebay. I squeezed a new bush into the top end of one yesterday, so now my project is a roller, on its wheels. (did I mention that I'm building a PRST-1 for my son?)

I have been pipe dreaming where the Preston design might have gone next, with a little further development.

I'm plotting manufacturing different, or adjustable H section pieces to go between the steering tube, and the top of the fork, to explore the relationship between rake and trail, and handling, that would be a cool project. Also, more radically, making the fork upright out of carbon would be very cool also, or even the whole frame?

I have also often thought about going further, and making a front end with two spherical bearings, and steering via a drag link, a bit like BMW's Duolever motorcycle set up. A good primer on two wheel dynamics is Motorcycle Chassis Design, by Tony Foale, writting first about 30 years ago, but physics never changes, right?

You mentioned that the front end felt rather odd to you, you do know of course about setting up the static sag of the suspension, then setting the damping to suit, rebound first, then compression? Its vital to get this right, or you will never get the thing to handle.

I had some decals made for my PRST-1 project, but I can't remember who made them. They were pricy, but certainly finish the bike off properly. I wonder if there would be discounts to be had for group buys?


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