Tempted to the dark side - GT Ultrabox 2!

[Mikku]

Here's a couple of before and after pics. I only had time for a quick test ride today, so tomorrow I'm going to check that everything's snugged up nicely, then switch over the magnesium DMR V12 pedals, also from the Crupi. If all goes to plan, I'll then head back to the track for a proper test.

[Mikku]

What better way to spend a national holiday than to hit the track! Sunny weather yesterday meant I was able to test out the UB2 with the Answer forks - an all carbon set-up! Unsurprisingly, the front end felt lighter and it was noticeably easier to lift up - not that it was difficult before but it just pops up easier now, as per the pic below. I need to borrow my neighbour's scales again because with the addition of the Daggers and magnesium DMR V12 pedals, also from the Crupi, the bike should now be around the 18lbs mark.

Save for a bit of tinkering here and there, and possibly a change of tyres, I'll about done with making any more major changes. New cranks would be nice but are an unnecessary expense at the moment. I'd prefer to spend my hard-earned on an overhaul kit for the Elite cassette, which sounds okay to my untrained ear but I'm assuming they're the original pawls and springs in which case they must be quite a few years old by now. So that may be a Christmas present to myself or I may just save that for next year's race budget!

[Mikku]

I borrowed my neighbour's bathroom scales again yesterday and with the Answer forks and DMR pedals, the GT's now coming in around the 8.2kg mark, which is about 18.08lbs in old money. I say "around"  and "about" because the readout moved slightly if I moved, so it's all approximate. Still fairly pleased with that though, especially seeing as I wasn't thinking much about weight-saving when I picked this up and started playing around with parts.

[Mikku]

Just a small update today. I tried and failed to find a replacement chain-tensioner bolt (to replace the one that had gone AWOL) but apparently a 40mm, M4, fully-threaded, allen head bolt is not a commonly-used item in Japan! I therefore resorted to our Chinese friends on eBay and ?1.25 and 10 days later, 5 shiny new bolts arrived. I had my doubts they would a) arrive and/or b) fit, but thankfully they did and do!

[Mikku]

I have just managed to pick up some of my favourite race tyres, the Maxxis DTH, which are getting harder to find since Maxxis brought out the Torch. Like the UB2, the DTH was designed for the Beijing Olympics and although tyre technology has moved on, so has carbon frame design, so I think the two are well-matched.

The Rubena Speedo LTs that were on the bike are actually slightly lighter than the 345g DTH. There were two versions of the Speedo LT, an economy version weighing 580g and an Elite version made from a "carbon racing extreme light tread compound". The ones on the GT weigh about 330g, which is the quoted weight for the Elites. I quite like them but since most of the tracks I run at are dirt, some still with dirt berms, I prefer the extra tread of the DTH. Plus they have a slighter lower profile than the Speedos, which I think gives the bike an even sleeker look.

When swapping over the tyres I had a look at the tubes and these are made by Onza, yet another new-to-me brand. They looked in good nick but are a 1.75-2.20" size, so I'll keep them for the time being but may replace them with a newer, smaller pair down the line. So that's about as far as I want/need to change things for the moment. I could do with another track test but that may now have to wait for the New Year. In the meantime, I think I've done enough to this bike to justify entering it in BOTM!

[Mikku]

After its glorious 2nd place (out of 2 ) in December's BOTM, the GT went into winter hibernation until last week, when I literally took off the dust sheet, took it for a quick spin around the rice paddies then onto my first track session of the year. The DTH tyres were fine, as expected, and hopefully I can give them, the bike and rider their first race of the season in the next couple of months. To that end, I couldn't resist doing a little more weight-weenie-ing!! Since the seat on these is almost redundant, only ever being used when sitting down in and around staging and the start hill, I have just bought a used, all-carbon seat weighing a reputed 100g! Coupled with another cut-down carbon post from eBay, I reckon on shaving another 100g off the bike's already svelte 8.2kg but we'll see, when they both arrive. I should add that I wouldn't consider riding on either of these, in the sense of putting my full riding weight on them whilst on the move, let alone at high speed, but for my purposes, on this bike, I reckon they'll be fine. Hopefully!

[fattaffracingco]

loving this thread

[Mikku]

Cheers mate!

It's been fun messing around with this thing, both on and off the track. The seat and post both arrived this week, so with a bit of spare time on my hands today, it was time to switch out the set-ups. First of all I had to sort out the post, which was sold cheaply for spares or repair as it had a split in the bottom. I therefore cut off the offending 15mm, sanded it smooth and mounted it up with the carbon seat. It looks a bit different to the Tioga D-Spyder and possibly not for the better, but I bought it for the weight-saving rather than aesthetics and I reckon the bike could now be sub-18lbs. 

[Mikku]

As part of the continuing evolution and upgrading of this beast, I've been looking at the drivetrain and in particular the Profile Elite cassette. Not knowing the history of the bike but making an educated guess that the main components are quite a few years old, I've been thinking about replacing the pawls and springs in the driver. After watching a few online vids, I thought I'd first have a butcher's inside. I removed the driver, then the pawls and springs, all of which were covered in grease. I therefore cleaned it all up before putting it back together. There's not much tension in the springs, so I'm definitely going to get a new set of those, and possibly the pawls too while I'm at it, even though they looked okay to the untrained eye.

I'm also thinking about replacing the BB with something newer, but we'll see.

[Mikku]

New springs have arrived! Profile said they had stopped selling the copper ones a few years ago, so that explains the lack of tension in mine.

[Mikku]

I had a day off today, so decided to switch out the old, copper springs in the Profile Elite hub for the newer, steel ones. Having recently taken apart the hub, it didn't take too long to do, plus I could take a few pics along the way. A couple of things I noticed. Firstly and unsurprisingly, the hub is now MUCH louder. It wasn't quiet before but the greater tension in new springs has definitely made a noticeable difference to the sound. I like it but then I run a Halo Clickster on the Quamen and that's even louder!!   Secondly, there's a bit of wear on some teeth of the cog. Not too bad I think, but I may pick up another one as and when.

[Mikku]

I've been thinking for a while now about swapping out the cranks for something BMX-specific, the Rotor ones being road/mtb cranks. I actually like them but they're causing problems with the chainline. As always, however, I don't want to spend big bucks or want something shiny and new. Browsing through the Bay the other day, I then spotted these DXRs. They're the older, first generation ones and have seen a bit of action but were priced accordingly and in my size (175mm). Shipping to Japan was also offered and at a very reasonable rate, so after a few messages with the seller, the deal was sealed and they're now on their way.

The pedal washers are the wrong size, being for the newer generation version, so I've sourced some og replacements over here. Next step will be a new BB, since the one on there now is for the Rotor's 30mm spindle and the Shimano is a 24mm. I've been wanting to replace the BB anyway, so that's worked out well. Now I just have to decide what BB to go for. Shimano is the obvious choice for a Shimano crankset but I've read nothing but bad things about Shimano BBs, mainly in terms of longevity, so I'm currently reading reviews and stuff online and seeing what's readily and reasonably available over here. Will update the thread when the cranks arrive and a BB has been bought!

[Mikku]

The cranks have arrived safe and sound and I love 'em. Just the right amount of wear to match the rest of the bike.

Thankfully the new pedal washers are also perfect! As an added bonus the ones that were one there are now getting a new lease of life on the until-now, washer-less Rotor cranks!

Next up is a new BB, then I can start to swap everything over.

[Mikku]

Yet another Shimano purchase!

[Mikku]

After talking about doing this for about 2 months, I've finally removed the Rotor cranks from the UB2! Not without a struggle and a quick trip to the lbs I might add, but the buggers are off. Or rather they were, because they're now back on, having been cleaned up and re-greased. After removing the outer bolt on the drive-side arm, I discovered some white crap inside, as per the first pic. Not sure what it was but after an initial wipe down, I removed the arm and sprocket with the self-extracting washer. With the drive-side off, I had a closer look and realised that more crap was coming out from inside the arm. Corrosion of some sort?? Anyway, I cleaned it up and continued with the removal of the non-drive-side arm. My initial idea of messing around with washers to straighten up the chainline has gone out the window with the arrival of the Hollowtechs, so I gave everything a re-grease and re-assembled it. I now have a 3 week break before my next race, so really want to switch over the cranks before then. Next purchase is therefore going to be a new BB.

[Mikku]

Purchase made! Actually, make that purchases!

[Mikku]

The Crupi BB finally arrived from the States last week (can you believe it took over a month to get here!!), so I was finally able to fit the DXR cranks. Not without some issues but I eventually got them on. And very nice they look too! The silver finish changes the look of the bike quite a bit but I like 'em, which is good because they're quite a bit heavier than the Rotors they're replacing. Heavier by some 400g, if my old scales are anything to go by! However, putting them side-by-side clearly highlights the difference, with the Shimano arms much chunkier and I'm guessing, stronger with it. Plus, more importantly, the chainline is now a lot straighter than before.

So how does it ride? Well, I'm pleased to say that I finally have a smooth drivetrain. Whether it's the new BB or the straighter chainline, or a combination of both (I suspect the latter), pedalling's now a much nicer experience! It's also weird looking down at those chunky silver crank arms and black BB.

Some people may not like the oil slick chainring bolts but I didn't think the black ones I had on there would go well with the Renthal ring. Plus I've been wanting something with an oil slick finish for a while now, and these popped up at the right time and price. Actually, that's been the story of the bike as a whole. Apart from the parts I moved over from my other bikes (the Answer forks, Renthal ring and DMR pedals), I've picked everything else up online and usually used. Which is fine by me since, despite its sexy lines, this was never meant to be a beauty queen but a race bike. A pretty one maybe, but a bike to be ridden and raced, as it was designed for some fifteen years ago. So, almost to the year after I picked it up, I'm going to say that this bike is done. At least as far as I want to take it at the moment. If the weather holds, I plan to give the DXRs a shakedown test on Saturday in preparation for a race on Sunday.

[Mikku]

Quick follow up:- gave the DXRs a good workout over the weekend including a race on Sunday. Unsurprisingly, the cranks and Crupi BB came through with flying colours. I really like how they look and feel, with no obvious downside to the extra weight. In fact the bike now feels a bit more solid than before, which is not a bad thing for a hollow, carbon fibre-framed race rig!

I've posted a longer, race report in the racing section, but here's a gate pic.