old guy with new school and crank probs

[fattaffracingco]

hi all , new to the scene and forum , I'm an old guy with 2 new school bikes , cheapy british made zinc bikes bought used from gumtree , the daughters I am keeping standard  ish but I plan to make mine into a bit of a 'frankenstinc ' ,any probs with parts and I plan to replace and upgrade as I go but on a budget, so mostly parts will be used and liberated from either mates or the good old bay of e, simply as we plan to use them with our camper van and I wudnt sleep if the bikes were expensive due to limited security on site
problem one - the crank is notchy ,goes tight then loose again , its a one piece crank , I opened it up and it was dry as a bone with no grease, I think someone has been in there before as one cage is damaged and 3 ball bearings are missing either lost or ground to dust
I slapped it back together with grease but its not right
bottom cage measures 58mm x 68mm am I correct in assuming this is American sized as per old school ? ( even tho british bike )
can I replace whole crank for a 3 piece and bottom bracket internals as well does this mean converting to sealed bearings or will I have to stick with the old fashioned cage n ball affair
I also plan to fit new chain and front sprocket at same time
I have done quite a bit of reading bit am still confused with sizes
advice wud be appreciated , thanks in advance , chris fattaff

[oldtired]

    pictures on the web show the zinc bmx's have a USA Bottom Bracket , if you can , post up a pic of yours just to confirm ,

 assuming it is......


 the one piece not being right , a new bottom bracket would solve this ,

http://www.ebay.co.uk/itm/4Jeri-Black-BMX-Bottom-Bracket-For-1-Piece-Cranks-USA-51mm-With-DIrt-Seals-/112575153805?hash=item1a3600868d:g:rB4AAOSw8-xZxrW8


if you go to a 3 piece you will have to change your pedals as well as one piece are 1/2" and three  piece are 9/16"

diamond back as well as a few others  do a basic three piece crank with a loose ball  USA bottom bracket meant as a direct replacement for a one piece ,    lots of em on ebay this ones unbranded but the same as the db one  dirt cheap

http://www.ebay.co.uk/itm/USA-SIZE-BMX-CONVERSION-KIT-ONE-PIECE-BOTTOM-BRACKET-TO-3-PIECE-CRANK-SET-/263065953589?hash=item3d3ff3e535:g:FWYAAOSwstJZV3v4


this kit has a sealed bottom bracket and better quality cranks , imo  a better option n still cheap enough

http://www.ebay.co.uk/itm/BIG-SIZE-USA-BMX-3pc-Cromo-Crank-set-cromo-axle-sealed-bearings-175mm-cranks-/282277298686?hash=item41b909c1fe



if your frame has a MID size bottom bracket then the first crank wont fit , the second crank will fit if you order it with a mid BB



front sprocket change ,   you need to take into account the size of the sprocket on the rear wheel this will determine the size of the front sprocket to get the gear ratio right,  gear charts are on the web , as an example most old school gearing will be 44 (front) 16 (rear)  as will most lower end bikes , new school gearing is usually 25 (front) 9 (rear)

[fattaffracingco]

thanks oldtired, really good info ,firstly thanks for reply and not snubbing me down to my budget choice of ride,even tho I'm a newbie I have already come across a certain selectiveness regarding brand loyalty but hey ho -- I'm now pretty confident that I do have the American bb but I will post picky in next day or so just to confirm
I will go with the iyo better quality crank
I have already bought a 25t front sprocket I will check that guide tho
funnyily enough altho both bikes same make they are slightly different styled with different gearing with one being 20 something and the other 44 t
I have quite a few pics on my phone but not on laptop so will have to link phone , sorry I'm not techy minded with computers
also will look into set of used pedals might go shimano ala old school
really really helpful info man, thanks , will update u on my findings

[griff]

Jim (oldtired) is full of sound advice 

Your freewheel will dictate which cog you run up front, if you're running a modern wheel set with a tiny cog on the back then you have to run a small cog on the front, you won't be able to chuck a 16t freewheel on a modern cassette hub
Ask as many questions as you want before you spend anything, that way you won't end up spending twice!

If you want to post pics direct from your phone there's a guide in the welcome section, you don't have to use a PC

[oldtired]

your welcome ,  as griff says better to ask ,

  if you can get the pictures up of the bike your actually changing the parts on , any  advise given  can be more specific 

[fattaffracingco]

top man I will do that piccy, im in work at mo, ive just double backed from weekend of nites , doh
probably post pics tomoro, had a new phone last week which probably doesn't help me , lol, thanks guys

[oldtired]

Jim (oldtired) is full of sound advice 

better than what some  say i'm full of

[fattaffracingco]

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[fattaffracingco]

got a load of photos now but I need to resize them, I need to do some homework first tho

[fattaffracingco]

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[fattaffracingco]

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[fattaffracingco]

sorry for the duplicates this new phone has fooked me head , damn this technology thing
ignore the carbon fibre wrap and stickers it is a zinc underneath, my daughter didn't like the graffiti stickers , anyways usa bb

[fattaffracingco]

https://www.wheelies.co.uk/Arcane

I was thinking of this chain also what d ya reckon

[Spen69]

Jim's advice on cranks will sort that problem out.

However why do you want to change your front chainwheel? Just put it onto whatever cranks you buy and get a top-hat washer to suit of the centre hole is the wrong size.

If you want to change it for appearance or damage then count the teeth and let us know, both on the front chainwheel and the free wheel or drive sprocket on your wheels and we can tell you the best combinations to suit. Unfortunately not one of the pictures you have put up show the correct side of the bike to work it out from but most important is the number of teeth on the back wheel as the chainwheel can easily be changed to suit, not the other way around.

[oldtired]

yes both US bottom brackets, as spen says count up the teeth on the rear wheel freewheels,

looking at the chain alignment the  black one, it  looks to be 25/16 ?


the chain wheels you have on the front are thin probably steel, this may cause  a small issue with a crank set  upgrade , the new crank set should come with a tophat washer to convert the center hole of the chainwheel from 23.8 mm to either 22 or 19 mm , the problem will the thickness of the  chainwheel will be less than the top hat so you will need a washer to pack it out,     you said you have aleady bought a 25t chainwheel?   i assume it is an alloy one , if so there should be no issue ,    cross that bridge when needed,

the chains in the link is  ok ,  if you llike it get it ,       as an alternate a KMC 510H  or 510HX   used by lots of riders, a little bit cheaper too 

[griff]

+ 1 on the KMC chain

[pickle]

I bet they spin quicker than a washing machine! 

[fattaffracingco]

good eye oldtired  the black one is 25 t 16-- the green is 44 t 18
the new front sprocket is an ebay special and alloy and much thicker
I seem to remember from years ago there was a special tool to remove the rear sprocket/freewheel is this correct ? or do they just unscrew from hub
and also is there a difference from spoked hubs and nylon wheel hubs ?
I'm only changing the gearing on the green one as I plan to do a little bit of ramp work if my body will take it ? but you don't know until you try eh ?

[griff]

if there's a 16t cog on the back then you need to change the front (unless you want to be spinning like a madman)

any rear hub that will take an Old School 16t freewheel will not allow you to go down much smaller (lowest would be 12 I think and only then if it's a flip flop hub)

typical gearing with a 16t freewheel would be 44 up front - 25:16 is way off

[Spen69]

Ok we're getting somewhere now.

Yes there is a special tool to remove freewheels but only certain types like Suntour or Shimano which if this is a cheap bike I doubt it will have. Take it to your local bike shop (lbs) and they can usually get them off but will usually smash them off so you need a new one.

What Griff said is correct, you can only go down to a 16t screw on freewheel on oldschool bikes unless it has a thread on both sides of the hub called a flip-flip. This has the old imperial threaded end for a standard 16t freewheel and a 30mm fine metric thread on the other side for smaller freewheels down to a 13t. The 12t was a mythical invention that broke straight away and never got into mass production so look for an Odyseey and make sure it is a RHD.

Either way you then match your front to the rear, so multiply the number of teeth on the rear by about 2.75

So a 16t needs a 44t
A 13t needs a 36t
Your 18t needs a 50t (never seen one of these, seen a few 48t?)

Hence a new school modern cassette hub with a tiny 9t driver cog needs a 25t front sprocket

You won't be able to ride a 25t-16t, like everyone has said you will be spinning round on the pedals but getting nowhere.

So post a pic of the rear freewheels if you can and we can tell you if you can remove it easily or not, and if either hub has threads on both sides take a picture of both. We can then help you work out what you need to do next.

Cheers

[fattaffracingco]

 thanks guys , yup I dropped a bollock ordering that 25t front , SHUD have posted here first , it was pretty n shiny and cheap but now er useless for me
yeah I have been on a gearing calculator now lol
0k as spen69 said I will have remove wheel and post a photo BUT ----
I have done a bit more reading and small front sprockets seem to only come into their own for grinding ? which I'm probably not gonna do (too old n fat )so  would I be better off sticking with larger front sprocket and just buying another and or reusing old one with spacer, but I wud like to do some ramp stuff of sorts
AWESOME forum tho guys, sorry for all stupid questions its a very steep learn curve for newbie
thanks for all advice in advance

[griff]

thanks guys , yup I dropped a bollock ordering that 25t front , SHUD have posted here first , it was pretty n shiny and cheap but now er useless for me
yeah I have been on a gearing calculator now lol
0k as spen69 said I will have remove wheel and post a photo BUT ----
I have done a bit more reading and small front sprockets seem to only come into their own for grinding ? which I'm probably not gonna do (too old n fat )so  would I be better off sticking with larger front sprocket and just buying another and or reusing old one with spacer, but I wud like to do some ramp stuff of sorts
AWESOME forum tho guys, sorry for all stupid questions its a very steep learn curve for newbie
thanks for all advice in advance

you don't have a choice
unless you want to buy a new back wheel as well

[griff]

tbh the best advice I can give you if you want to ride is to sell the ones you have got and buy a decent 2nd hand new school complete
by the time you've swapped bits around here n there you'll probably end up spending more anyway - I bought a full cromo bike with 3pc cranks and sealed hubs etc 2nd hand for £100

[fattaffracingco]

re griff - tbh mate you are probably right it might well in long run be cheaper to buy another,  but they were £50 for 2 bikes , one is now my daughters  and I kinda wanna put my own stamp on mine , it has problem with crank which I have to repair or replace , I just thought I would upgrade and replace chain and front sprocket at same time
And its not just about the money either, although as I said earlier I wanna do it on budget , I thought u cud swap sprockets for just anything as same as motorbikes and I kinda like arsing about in garage getting my hands dirty

its the only peaceful place in house !!!! does that make me a bad dad ?? lol

SO  I think its the 3p crank as recommended along with chain as per link with possibly new front std gearing and used pedals from the bay
wots your opinion on larger front sprockets on ramp work 
again awesome info guys

[oldtired]

  green bike ,  swap  out the freewheel on the back for a 16t , and try to find a thicker alloy 44t ,   as spen said lbs will help, i also doubt it will be  shimano or suntour fitting 

as said earlier, assuming you get a 3 piece,    the steel front chainwheell won't be bad it may just need washers to make the top hat fit, and get the chain alignment right, easily done , there is also way to adapt the top hats for these thin chainwheels , again sort that as needed. keep the old one piece bottom bracket 

 only problems with a 44t up front on ramps is it will catch when rolling in , however this can be easily avoided by lifting the front wheel a little on the way in ,or altering the angle you roll in ,   if you get on to riding ramps you'll pick this up real quick,  we all rode big sprockets up front in the past , in fact they're spot for doing a mid school coping bending disaster     "CLANG!!!!!!!!  YEAH BOY" 

the parts your opting for will improve things , but , tbh your probably up to about £50 in bits for this to get it rolling  better , although entirely up to you,  imo that's about the limit  for the type of bike it is,   nothing wrong with it at all ,  but as griff has said for not a lot more you coud pick up something that is a new school bike, and more suited to skatepark use, if you decide to have a go at ramps