View Full Version : a question for all you bmx bandits
i know some of you good people like to ride those funny little bikes that don't appear to stay on the ground for very long, and need expensive trainers to slow them down.......
i am on the scrounge for a set of front & rear wheels for one...
i am working on next years hinckley soapbox racer & have acquired one bmx as a donor, and i don't trust the 20" mtb wheels, as they have a lot less spokes & come with knobbly tyres.....
can anyone help????? i would be prepared to spend some money if necessary..... please pm me
ps. forum mods, i apologise in advance if this is in the wrong section.. mike
mk1nova_rich
30-07-14, 05:00 PM
3/8" or 14mm thread...or are you removing the centres?
Do you already have some 20" MTB wheels, or are you just saying you dont want them?
craig green
30-07-14, 07:22 PM
Must be serious BMX wheels if you have 48spokers. A 20" wheel is so small that structurally they should be waay stronger than a typical MTB wheel, so I'd assume a 20" MTB (assume childs bike) ought to be up to the job.
Not that I would doubt your expertise Mow'.
mk1nova_rich
30-07-14, 07:35 PM
Stick MTB wheels on the front...my old BMX had a 36-spoke wheel on the front and stayed straight and true for 3+ years of abuse (ok it wasnt a cheapy cheap wheel but was nowhere near top of the range)
craig green
30-07-14, 07:39 PM
I'd say the quality of the wheel is the most significant factor. Some cheap chinese bike wheels are just awful from new, I've seen hubs with 2 ball bearings in one side (should have approx 10), with next to no spoke tension. That's just destined to fail.
How about 20" front and 26" rears?
mk1nova_rich
30-07-14, 08:40 PM
I'd say the quality of the wheel is the most significant factor. Some cheap chinese bike wheels are just awful from new, I've seen hubs with 2 ball bearings in one side (should have approx 10), with next to no spoke tension. That's just destined to fail.
I used to piss my mates off cos they had to pedal to keep up with me rolling on my BMX as the bearings were **** hot lol
ok, i'll try to answer....
re the bmx vs. mtb wheels..... the fastest 10 soapboxes this year were all using 20" bmx rims & tyres, it didn't really matter whether they had 3/8 or 14mm axles, but the 2 wheels I have are 3/8". I plan to use the rear wheels with their original axles in some suspension rear ends I already have, but I am looking at fitting the best bike bearings I can afford... as for the front end, I intend to use m12 or m14 bolts with small roller bearings fitted into the hub races.
Stu, 26" wheels seem to have a lot of inertia issues, and also aren't very strong under hard cornering, this is based on watching the racers that had them on & they were collapsing far too often...but we did think about making a soapbox that looks like a tractor with 26" rears & 12" fronts... we drew a basic plan & then realised we would struggle to make it in the time we had.
one of my current 24" rear mtb wheels snapped a spoke at the chicane, causing a fairly major buckle & subsequent brake drag, ruining the time for the run, I think I've reached the limit of the 24" rims, and I can't get decent road tyres cheap enough for them, compared to 20" ones....
Must be serious BMX wheels if you have 48spokers. A 20" wheel is so small that structurally they should be waay stronger than a typical MTB wheel, so I'd assume a 20" MTB (assume childs bike) ought to be up to the job.
Not that I would doubt your expertise Mow'.
Doctor, most 20" kids mtb's are truly shyte. they are heavy & weak, with hardly any spokes, and 18 speed gears for some strange reason... even the 2 bmx rims I have, which are cheap generic chinese ones, are way stronger than the mtb ones I have...
That's the problem with most stuff these days, its built cheap but sold for upto good money....
Make some carbon discs
mk1nova_rich
30-07-14, 10:43 PM
What about 16" kids BMX wheels on the front?!
Can you stretch to £17 each for some Maxxis Hookworm tyres? they will drop your rolling resistance to buger all lol
by next july, I might be able to afford a set... I was going to rely on blowing them up quite a lot & maybe rigging up a tyre tread 'lathe' to leave a minimal contact patch for straight line running.
High pressure would be enough really
I'm more concerned about creating a decent braking setup..
after we had a great run, which ended with another monumental crash, which caused my 2nd daughter to collect the 'most enthusiastic racer' prize, to install an ass brake..... the American soap boxes have a section of car tyre rubber fixed to a plate under the seat that is locked in place until a bell crank lever is moved, making the drivers weight push the plate down onto the road giving massive braking....
here is the pic that graced the front of the local paper..... rosie genuinely took off over a bale and then topped it by tw@tting the end barrier fast enough to knock a rear corner off again......
http://i4.hinckleytimes.net/incoming/article7395844.ece/alternates/s615/Hinckley-Soap-Box-Derby-2014.jpg
Get mtb hubs fitted and use discs
jimbob-mcgrew
31-07-14, 04:06 PM
looks awsome mowgli, your daughters a nutter lol
i need to have a go at this next year... i could slap something together out of wooden pallets and pram wheels
mk1nova_rich
31-07-14, 05:09 PM
Get mtb hubs fitted and use discs
This is your best bet - a decent bike shop won't charge the earth for building a wheel if you supply the rim and hub. Spokes are pennies especially if you arnt bothered what colour they are
Get mtb hubs fitted and use discs
I like this idea, and if I can find enough donor parts, i'll give it a go for the fronts... the rears will be block, cos its still a decent setup with the 24" trailing arms.. I'm just going to get brake lugs welded on to suit the 20" rims
mk1nova_rich
31-07-14, 08:18 PM
Does it really need front and rear brakes? Asking merely out of curiosity
when you watch your daughter smack a set of bales & barriers that are against the Barclays bank wall, removing a corner of the chassis in the process, it sort of wins the argument...
ps. jimbob, my daughter rosie wants to hit you cos she took offence at your comment... I tried to explain that it was actually a complement
cable discs for cheapness.
Everybody upgrades to hydraulics in mtb world so some ebay bargains to be had.
I sold my rear brake for 2 quid minus the rotor,which are cheap on ebay too
mk1nova_rich
31-07-14, 08:29 PM
Yeh that makes sense lol is this event annual or quite regular?
+1 for mechanical discs
jimbob-mcgrew
31-07-14, 08:52 PM
when you watch your daughter smack a set of bales & barriers that are against the Barclays bank wall, removing a corner of the chassis in the process, it sort of wins the argument...
ps. jimbob, my daughter rosie wants to hit you cos she took offence at your comment... I tried to explain that it was actually a complement
lol yeah - nutter means: daredevil, adrenaline junkie, that likes to go fast, which is :thumb: :thumb: deffo cool
i reckon 4 lots of U-brakes on bmx wheels would be pretty decent.
2 rear brakes on a left hand lever, and the 2 front brakes on a right hand lever, just like a bike. would stop alright with some half decent pads.
theres usually piles of used/unwanted/scrapped bikes at waste disposal sites, next time you get rid of aload of rubbish, you could grab 2 bmx's for cheap and construct a monster for next year :)
jimbob-mcgrew
31-07-14, 08:55 PM
Yeh that makes sense lol is this event annual or quite regular?
+1 for mechanical discs
i think its just once a year rich, in july.
not sure if the locations always the same, but was in london this year
Yeh that makes sense lol is this event annual or quite regular?
+1 for mechanical discs
the Hinckley one is annual, on the 1st sunday in july...
you will find these sort of races all over the country, some have unique(this year, the Hinckley scrutineer was a retired woman with no clue whatsoever) rules & some have more organised rules & regs. there are clubs & associations all over the land. the Hinckley one is one big hoot of an event & free. it is split into 2 age groups, and 3 categories, basically, the rich, serious ones, charities & people like me, making them out of junk for the hell of it. we all help each other, and have a laugh too. this year, the town got 8000 people turning up to watch, it was rammed.
lol yeah - nutter means: daredevil, adrenaline junkie, that likes to go fast, which is :thumb: :thumb: deffo cool
i reckon 4 lots of U-brakes on bmx wheels would be pretty decent.
2 rear brakes on a left hand lever, and the 2 front brakes on a right hand lever, just like a bike. would stop alright with some half decent pads.
theres usually piles of used/unwanted/scrapped bikes at waste disposal sites, next time you get rid of aload of rubbish, you could grab 2 bmx's for cheap and construct a monster for next year :)
I tried separate brakes last year & rosie crashed too.... I am planning a large foot brake working all 4 wheels together
oddly, I noticed something odd this year. the braking zone is exactly where the large burger van always parks for the Saturday market, and the seriously fast ones were skidding & sliding all over the place trying to stop.. next year, I'm taking some detergent up to clean it off too.
as for the council tips.. Leicestershire ones give them all to a charity, so we get no look in. the best place I get them is by going for a drive round the local estates on a sunday morning before the pikeys get there!!!! lol I also put ads in the local rag
mk1nova_rich
31-07-14, 10:51 PM
I tried separate brakes last year & rosie crashed too.... I am planning a large foot brake working all 4 wheels together
That would surely be easier to rig up using hydraulic brakes then? It could be possible using cables but might be tricky getting all 4 to pull evenly
jimbob-mcgrew
31-07-14, 10:54 PM
the Hinckley one is annual, on the 1st sunday in july. you will find these sort of races all over the country
i didnt realise they were all over the country. 8000 is huge for humble hinckley!
I tried separate brakes last year & rosie crashed too.... I am planning a large foot brake working all 4 wheels together
seperate's no good... damn.
the 4 way footbrake should be good, sounds tricky.
it is really easy to rig up 4 brakes to a brake pedal, new long cables are £1.50 each from wilko, and you just need to rig up a brake pedal so it pulls, fit a bias bar and then use an adjuster at each end of the cables. I know I made it sound simple, but discs need different travel to blocks, and as long as the discs pull the same & the block brakes pull the same, then trueing the wheels & adjusting the cables will sort out most of the issues. the brakes also need a bit of front bias or the soapbox just spins.
oh & I've been putting a lot of thought into it.
Hi mowgli, randomly came across this, well theres bmx's out there that came with double disc as standard (idea didn't really catch on as they don't last long in skateparks and abit dangerous on a bmx imho)
as example there was one i remember being called a silverfox avalance i think?, they were only like 80quid new but idea for what you need, plenty of them on ebay for about 30£ :)
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