munchh
Rider
Make it, ride it, break it, make another.
Posts: 8
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Post by munchh on Jun 2, 2009 23:44:50 GMT
OK so im a total newbie. So i've got various bits, i've read the rules, is it a case of just interpreting them and thats it, is there any typical newbie mistakes you could point out? I'm starting the build, i'll update with pics. Cheers.
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munchh
Rider
Make it, ride it, break it, make another.
Posts: 8
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Post by munchh on Jun 3, 2009 13:22:46 GMT
I have seen alot of flipped frames, is this a proven thing to do?
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munchh
Rider
Make it, ride it, break it, make another.
Posts: 8
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Post by munchh on Jun 3, 2009 14:01:10 GMT
.....and the more i read it i wonder why you cant use any frame that is for 20" wheels, so is there any reason why a full suspention 20" mountain bike frame would not work?
I've seen bikes with suspension forks?
questions....questions......
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munchh
Rider
Make it, ride it, break it, make another.
Posts: 8
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Post by munchh on Jun 4, 2009 15:29:44 GMT
I have been reading Mcswift's QandA's, Trike talks about tyres, so i started searching, www.legslarry.beerdrinkers.co.uk/tech/GS.htmthis was pretty interesting, Is it best to have a slightly bigger tyre on the front? are you better on a wider tyre like the 2.1, or do you stick with 1.75, or one of each? I'm 5'8" tall and just under 15st, it looks like i'll be using a standard frame, not sure what the make is as its been debadged, but i went away from thinking i could use the ageing chrome (aero) burner frame, i dont think its got enough meat on its bones and novelty value comes second to my heath or my wife will kill me!! hehe
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Post by Ian r on Jun 8, 2009 13:33:36 GMT
Hi I'll try and answer these as best I can, based on my experiences so far..... Flipped frame? NO. seems like a good plan from a head angle pov but only handles well at very high speeds and most of us like to corner ! also makes attching other components complex (seats, mostly) Brakes. V-brakes, atleast on the front, are nearly a must. see if you can find a local welder to put some bosses (mounting posts) on the forks for you (or diy if you can). That pic of the chrome frame looks very much like my first gravity bike frame, so not an issue with strength as long as it isn't too far gone :-) No reason at all why you can't use a mtb full sus frame and fit 20" wheels and disc brakes all round (has been done regularly in the states, and we have a full sus, faired gravity bike in the garage somewhere....). Down side is complexity, reduced flexability of bike weight (maybe, depends on mtb frame) and summat else to go wrong or break when you fall off ! Tyres. I run a 2.1 on the front & a 1.75 on the rear, like you suggest. This gives confidence for cornering whilst a bit of a compromise for rolling resistance. But it depends on the course. Sometime I run swalbe stelvio dual compounds front and rear if its a long, fast, flowing course without too many challenging corners (ie NOT scammonden ! ) or i'm riding the full susser.... Seat. as low as it'll go, as big as you can get Handle bars. I used to (and still do, depernding on course) run racing bike drop handle bars, with a drop stem (or an adjustable stem, ideally) but some places suit flat bars. Depends on top speeds, how aerodynamic you want / need to be versus handling. Drop bars put alot of your body weight through your arms which can be tiring on long runes (aviemore & the alps) and for the inexperienced can provide the onset of a speed wobble ! But they are faster most of the time...... Knee / foot pegs. Go as big a diameter as poss (less stuff to stick in yourself or others when crashing) and experiment with pegs at both the bottom bracket position and / or rear wheel. I'm currently running both (knees on BB, anlkes at rear wheel). but, again depends on course. Going back to tyres. Make and model not too important to start with. Don't be tempted to pump 'em up too hard to begin with , 55psi shopuld be enough for starters. Get used to the bike with lower pressues, then increase them as you become more confident with the level of grip they provide for a given pressure. By all means, have a slow (ish) practice on a quite country road (remeber your reflectors and you're fully legal) but for proper testing I recomend Gurston as the most suitable closed road event to chuck the thing round corners at ;D Happy building Ian
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munchh
Rider
Make it, ride it, break it, make another.
Posts: 8
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Post by munchh on Jun 8, 2009 14:09:02 GMT
Nice one Ian, heres the 1st mock up! So straight away i know i need the seat lower, unfortunately the sissy bar wont let me, but i'm looking into getting a pair of supports made that will, my knees are nowhere near the bottom bracket pegs! ;D But i will use the seat. Just sitting on it i can see what you mean about weight on the arms, alot of the reason i dont like racing style motorbikes, i keep describing this to people as a 'cafe racer'. Heres the brakes, i have the same on the back.. i did want to use kids bmx bars, i know ive got some, but i cant find them, they would not drop so far and would be narrower. So are you better off having your hands higher and dropping your elbows?? Its all a work in progress i suppose, at least i got the shock forks, oh and my leathers are coming for fathers day....wohooo!
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Post by Ian r on Jun 8, 2009 15:38:12 GMT
aye. looks good :-) Yeah, 'preying mantis' sylee works ok !
Let me know when you're heading down to Gurston & I'll try and get along (been meaning to this year anyway)
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munchh
Rider
Make it, ride it, break it, make another.
Posts: 8
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Post by munchh on Jun 8, 2009 17:17:32 GMT
Where is that, sailsbury way? I think the 1st test is going to be at Hog Hill the 27th-28th this month, there is a slalom race weekend that i will be at www.ncdsa.com/contest_registration.asp?ContestID=420 , there is another guy who has built one also, i think more than one counts as an unofficial race! The new cycle track is amaizing and massive, we have had lugers, so why notG-bike?
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Post by mutts nutts racing on Jun 11, 2009 19:32:19 GMT
Hi Munchh, good to see someone is getting into this....!! I've only been at it less than a year and it's the cheapest grins per mile you can get............. ;D If you haven't done so already then you should check-out www.gravitybike.com lots of helpful threads especially about how to attach different types of kneelers ( i couldn't use the bottom bracket way either). To address a couple of points you raised - I agree with Ian, don't flip your frame - way to twitchy. Best brakes you can get - i used an old MTB fork (took all the internals out and just put a long bolt through) this already had disc brake bosses fitted and i can't weld. Tyres - I run a 2.1 Animal (ASM) at the front and a 1.95 Animal (ASM) at the rear. When i started i found a local slope (don't have hills here in Suffolk) and spent a morning trudging up and down with different tyre pressures to see which worked best re: speed and stability. Again as Ian says come along to Gurston to have a great day out and a blinding hill - I think Ian's hill record is safe while I'm on the hill - well rapid !! Last couple of things - handle bars - cut 'em down so they are just an upside down U shape, about where the brace is (I use and old MTB bar cut down to about 10" wide, again like the forks they were in the shed) and lastly only change one thing at a time, do a test run see if it works the try something else. Well theres my two pennyworth, good luck with it and see you hopefully at Gurston or even Eastbourne in Aug, Mutts Nutts Racing.
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munchh
Rider
Make it, ride it, break it, make another.
Posts: 8
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Post by munchh on Jun 11, 2009 19:35:51 GMT
Well the final mock up is ready for testing. All the breaks are on and a angle grinder and a vice later the sissy bar mod is done. The seat is at the lowest it can go i can raise it about an inch at a time at the rear, only a hill can tell. So as soon as my leathers are here and i find some gloves, its all go. So whats the deal with having padding over the bars and headset?
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munchh
Rider
Make it, ride it, break it, make another.
Posts: 8
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Post by munchh on Jun 12, 2009 10:41:17 GMT
Much nicer riding position
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