psycholist

As they say about Ireland: It would be a lovely country if we could only roof it ...

Worryingly the bike I have now is my cost no object ultimate machine... The option to buy every new bike that comes out to see if it's better would be good though - you can never have too many bikes . With craploads of cash I'd buy a large warehouse and build trials obstacles in it (Or pay people to...), so when it rains for several months continuously I'll still have somewhere to ride. Quitting my job to give more cycling time would also make sense - though my current job allows me to disappear during work hours if the weather's looking good anyway... Emigrating somewhere warmer and drier would be better again of course .

What I find really weird though is that some left foot forward riders prefer to sidehop to the left (My preference) and spin the front to the right, while others prefer exactly the opposite with the same foot position.

If the chain isn't wrapped around enough of the back sprocket it can sometimes lift right off the teeth under load. See if you can take another link out of the chain to shorten it up, so the derailleur is pushed right up towards the chainstay and the chain wraps around as much of the back sprocket as possible.

What's your chain tension like? If the chain is reasonably tight it can't slip. If you're getting clunking from the chain as you pedal, the chainline might be off, causing the teeth of the sprockets to catch on the side plates of the chain.

In ordering from Ireland I run into an even weirder problem. I think it's a yahoo based paying thingie you need to pay online, but yahoo won't allow me to register as even though it changes to yahoo.ie for the registration it's still looking for a post code (Ireland outside Dublin doesn't have post codes at all), and nothing I've found to put in the postcode box will placate it so far. Since the postage isn't automatically calculated for outside the UK I have to ring anyway to get postage quoted, so not a big deal at all, just more technology not quite working correctly . For the tartybikes employees reading this - thanks again for the Echo Control - that bike has improved me more in the past 3 months than I improved in the year before that .

The aluminium centre of the star nut in the urban fork has a 10.5mm outside diameter. The steerer is 18.3mm inside diameter. This leaves you 3.9mm around the star nut. Less than the 5mm needed to put a magura line through. The good news is if you file a chunk off the aluminium centre piece of the star nut there will be space. The problem is once you completely cut the steel star part of the nut it probably won't grip in a useful way on the inside of the steerer .

If it's a Hayes 9 it's a dual piston brake. If it's a Hayes Sole remove it and throw it in the bin now before it really starts to annoy you. First check that the disk runs in the centre of the brake caliper. No point going any further without adjusting it if the caliper is off to one side. If it's a Hayes 9 and you only see one piston moving then it's likely the seal on the other piston has got stiff. Remove the wheel and lever the brake pads back with a clean screwdriver (The wider the blade the better - any grease/oil on the screwdriver will contaminate the pads). On other brakes I'd say to remove the pads, but the Hayes pads mount onto a nail head in the centre of the pistons, which is very easy to break off and requires the piston to be replaced in order to fix it, so better to sacrifice your pads (Which experience far worse when you're using the brakes normally anyway, so they'll be fine). Once the pads are back as far as they'll go start pumping the lever while holding the piston that was moving correctly in place to force the other one to move. Run the piston out and back a few times, checking to see if both pistons move when the lever is pulled. Once they're both moving put everything back together and try it out. Hayes pistons tend to seize after a few years use, so if this is the problem getting the piston moving might take a bit of force - make sure you're not wedging the piston sideways as you push it back though. For Hayes Sole you can wind in the stationary brake pad to give the brake its bite back - this is done with an allen key in the back of the caliper accessed through the spokes. There's a grubscrew locking this bolt in position, so undo this before adjusting the stationary pad in. Setting it up so the moving pad flexes the disk a fraction if a mm before it hits the stationary pad is the way to go here. Once you pads wear about 1/3 you'll find there's no way to get the brake to bite well on the Soles however, so either keep feeding them pads you barely wear or replace with a brake that doesn't suck...

As for what the ratios mean, this line of thinking works for me: A bike chain has pins 0.5" apart --> every sprocket tooth carries 0.5" of chain. An 18 tooth sprocket that makes one full turn will move the chain forward 9". This 9" chain movement must drive the back cog 18 teeth forwards. If the rear cog is 18T it will make one full turn. If it's smaller than 18T it will make more than one full turn (The ratio will be greater than 1 - that is one turn of the pedals causes more than one turn of the wheel). If the driven sprocket is bigger than 18T the sprocket won't make a full turn, giving a gear ratio less than one. A guideline I've made up for picking a gear (And most trials gears seem to be on or about this figure) is that half a turn of the pedals should move the bike forward between a wheelbase length and a wheelbase plus a half tyre length. This means that starting with your good foot to the back and turning the cranks a half revolution to your preferred pedal position, will either get you from having the front tyre on an edge to being on the back wheel on the edge or from having the front wheel against a vertical rise to being on the back wheel on top of it. For a 26" bike, wheel circumference is 26(pi)" = 82" (Rounded here, not in my calculation), take wheelbase as 42" (1067mm) + 13" for the front wheel radius, so for the bike to move to the correct spot the wheel has to turn 55/82 of a turn or 0.67 of a turn. This 0.67 of a turn is driven by a 0.5 turn of the cranks, so the gear ratio from this is 0.67/0.5 = 1.347, which is a little on the high side, or for a wheelbase movement 42/82 = 0.51 turns of the wheel = 0.51/0.5 = 1.028, which is a little on the low side. I'm pretty sure the same rule holds for 20" and 24" bikes too. Are mods usually geared between 1.337 and 1.655 and 24" bikes between 1.114 and 1.432. There are always going to be outliers, but I've always run a gear around 22:17 (1.294) on a freehub and currently use freewheel with 18:14 (1.286) gear, which is a little over the average of the values I've calculated (1.187), but I think I run a slightly higher gear than average anyway. For a 1080 wheelbase 26" bike the average of these figures is 1.2002. This matches surprisingly well with the 18:15 (1.2) ratio a lot of people like... If you know your wheelbase and wheel diameter I'd be interested to hear whether your gear is within the range calculated anyway - I've never heard anyone else describe trials gear choice in this way, so it'd be nice to see if practice and my theory match .

I'm pretty sure there is, but I'll check this evening. I have a set of urbans on my bike and a spare star nut to measure.

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Either part of the headset is missing or the bearings have moved out of place and jammed the headset open. Open it up and have a look inside.

Run longer brake lines so you can give the bars a full spin without snagging anything? That'd be the very simplest solution. Another option would be to drill out part of the star nut (They're a weird small size in the urban forks, the steerer is so thick) and top cap and run the cable through there. Since the start nut basically does nothing once the stem is tightened it's not a structural worry like putting a hole in the steerer tube would be...

Have you got a big dirty DH tube fitted already? Intense do some very serious looking ones. Should provide some pinch protection. Failing that are you running the tyres too flat - remember that for a 24" wheel the contact patch will be shorter, so the same tyre pressure will cause more tyre deformation than for a 26" tyre.

... and the aqueduct - or am I mixing them up with the Romans ...

I used to use Maguras for XCing. If I had no choice but to run rim brakes I probably would again too. Maguras don't have the power wet or dry that a similarly priced set of V's will have, but they stay working in the worst mud, dirt and slime without me needing to constantly adjust/replace the brake pads, replace the cable, have a grindy brake feel etc. At this stage the only people on Maguras are trials riders and German cycle tourists as far as I can see... For XC use I never ground the rims - the mud provided more than enough grinding without any help. If it was really bad I could wear through a rim in a year just from braking on it. I think I've replaced a trials bike rim once for the same reason in 6 years of having a specific trials bike. Disks are better in every way for XC riding unless you live somewhere very very dry, in which case V's would probably stay working properly...

As a quick guideline half the amount you paid for it. If any structural parts are more than a year or two old take even more off it. If I was buying second hand I'd definitely want to know how old various parts are before putting my money down - nothing worse than snapping a bike you have no warranty on...

A grub screw will do a crap job holding the tensioner. Once the tip of the screw has dug a hold for itself in the axle the tip of the screw will aim for that hole every time you try to tighten it. A pinch bolt like that shown in the picture at the start of this thread is a much better idea.

Tioga 2.1" tyres tend to be a lot bigger than other company's 2.1s. Avoid the XC Tioga tyres anyway - I've seen too many people wash out on dry concrete using them. If it gets wet they're even scarier...

I changed bike at the same time and since I was only planning to use one gear I specifically only bought singlespeed parts. Freewheels seem to be better value for money and less likely to crap themselves than freehubs, so it was an easy decision. Only thing I don't like about freewheels is that your pedalling is acting to tighten the freewheel onto the cranks, so it'll be a complete basturd to remove it when it does need replacing, mounting the freewheel onto a deep spline on the crank with a cassette style lockring would be a lot better I reckon...

My experience with Conti tyres is that they're light but they don't grip on anything unless it's dry. The Maxxis advantage is my XC tyre of choice and would make a very good trials bike front tyre too I reckon. 2.1" wide with a very round profile and lots of air volume, so on a wide rim I reckon you'll use the full width of the tyre tread.

For comparison I get about 3-4 years from Deore cranks and got less than 6 months from the Race Face XC cranks (Which cost more than the deores AFAIK). I wouldn't recommend hollow deore cranks for a trials bike either - unless you never touch the cranks down...

I have access to a LWB merc sprinter van ... That'd carry a lot of pallets, but the crime would definitely be noticed if we used that. You'd be amazed what you can get if you just ask though...

The tyre in the photo looks a lot like a front WTB velociraptor: http://www.bicyclemania.co.uk/images/logo%...r%20f&r.jpg They're pretty good tyres. There are XC high rollers available in 2.1" and they're pretty light. I love my 2.35" minion on the front though ... I used a bulldog on my last bike and it was pretty good, though it let go in a couple of strange places in damp conditions. Try finding more of those red michelins from the early 2000's - everybody used them for years .

The brake isn't particularly spongy. I just reckon that since I need something to protect the crossover line and there's a possibility of reducing arm pump by further stiffening the brake I may benefit doubly from this change. Also I need to spend more time riding my bike than making replacement bits for it. I made bake booster for evo mount Maguras from 5mm plate steel back in the day and they were awesome, but that was when I had a lot more time than money ...