Author Topic: new to bmx - bit of help please (Read 3870 times)

dan_b · « **on:** August 30, 2012, 08:08 PM »

i had joined another forum that came up earlier and posted there and with 4 hours of having a post up didnt got 1 view so decided to try here.
i have just bought a bmx for my son a hoffman disruptor with a few extra bits on and decided to have a go myself so found one and picked it up today.
its a wethepeople arcade frame with few salt parts and a stolen upgraded sealed rear wheel. its been over 10 years since i had a bmx and dont know much about them to be honest so any help would be great. all seems good with the bike apart from both crank arms have slight play in them, and im unsure if this is a bearing problem or the crank itself. i noticed the allen head bolt that goes through the crank arm was loose and tightened finger tight which has stopped alot of the movement so i think they just need stripping and putting back together properly and tight. any tips on how to strip them down and build them back up would be great and hopefully no damage has been done and can ride tomorrow and start enjoying the bike. thanks

harris · « **Reply #1 on:** August 30, 2012, 08:11 PM »

The pinch bolts need to be real good n tight,thatll stop the play.
if its loose bearings then you might need to remove the none drive side arm and tighten the bottom bracket then refit arm

Discostu · « **Reply #2 on:** August 30, 2012, 08:22 PM »

Good advise there dan.

If you get any play after it's all tight then you probably have something that is worn out.

dan_b · « **Reply #3 on:** August 30, 2012, 08:37 PM »

thanks will give them a good clean and tighten them up. how do i tighten the bottom bracket mate? do i need to use any specific grease or any thread lock when putting back together? chain also seems a bit loose is there any general rule of thumg for setting chain tension? thanks

harris · « **Reply #4 on:** August 30, 2012, 08:42 PM »

can you get a picture and i will talk you through it.

GaryN · « **Reply #5 on:** August 30, 2012, 08:42 PM »

I could be wrong but I think that the Arcade is a reasonably new frame so it is likely to have sealed bottom bracket bearings so these will not be adjustable.

As you have already noticed that the large allen bolt going into the crank is loose then my money would be on just tightening everything up.

I would do the following.

Firstly if possible use a good quality set of allen keys as they will prevent damage to the bolts and allow you to get them good and tight.

Loosen off the allen bolt at the rear of the crank arm (pinch bolt).

Tighten up the large centre allen bolt as this will push the arm onto the crank.

Tighten up the allen bolt at the rear of the crank arm (pinch bolt).

Do both side the same and then just make sure that the cranks spin freely and hopefully have no movement/play in them.

That should be job done.

harris · « **Reply #6 on:** August 30, 2012, 08:44 PM »

youtube has some vids

/>try a few might help

dan_b · « **Reply #7 on:** August 30, 2012, 08:49 PM »

thanks will post up how it goes and put some pics of the bikes on. is there a weight limit on these bikes. i did a bit of reading before i bought it and it has a 4130 chromoly frame so should be ok there.

dan_b · « **Reply #8 on:** August 31, 2012, 10:22 AM »

i have took the crank off and stripped it down. the green fell off one of the bearings i checked for play with just the shaft through the bearings and was no play just didnt turn very freely so going to grease that back up. do the bearings need changing or can i just press the cover back in? if not the code on bearings is r12-2rs so should be able to get some easily if need doing. thanks

HARORIDER · « **Reply #9 on:** August 31, 2012, 10:38 AM »

if you are refering to the green cover that goes on the bearings themselves and you can now see the bearings from the outside then it sounds like they need replacing,is it like this ?

dan_b · « **Reply #10 on:** August 31, 2012, 11:53 AM »

yes they are mate the green cover came off but does clip back in. can i use copper grease when rebuilding the crank? thanks

GaryN · « **Reply #11 on:** August 31, 2012, 02:59 PM »

I wouldn't use copper grease as its purpose is more for high temp and anti seize applications.

Just a general water proof bearing grease should be fine. I tend to use Finish Line Teflon grease or failing that Castrol LM grease.

I have heard of people removing the covers and re-packing with grease so well worth a try and see how it goes.

dan_b · « **Reply #12 on:** August 31, 2012, 06:26 PM »

i have just built it back up using bike grease instead of copper grease. all the play has gone but if i tighten the end bolts right up the arms dont spin freely and are stiff. are they not meant to be tightened right up. also noticed the splined shaft doesnt go right through the arms and only went through both about half way is this right? thanks

pickle · « **Reply #13 on:** August 31, 2012, 07:08 PM »

Do you have any spacers on each side? And do you have a spacer in between the bearings in the middle of the axle?

Would be better if you can bang up some pictures

dan_b · « **Reply #14 on:** August 31, 2012, 07:25 PM »

there is 1 spacer on the non drive side and 3 else 4 on the drive side plus the stepped one which sits in the sprocket. i'll take it back to bits and take some pictures. there is a spacer inbetween the bearings. are the bolts in the end of the shaft meant to be as tight as can go or nipped up until the arms spin as you want.

harris · « **Reply #15 on:** August 31, 2012, 07:31 PM »

the spacers on the drive side are to get the front sprocket to line up with the rear,the non drive side is to make sure the crank arm clears the chain stay
the center tube is ment to be a tad loose but when you tighten the axle bolt itll pull in the slack so the arms spin free against the bearings
if its not free youve over tightened the bolt.
mine are always very tight.some dont use the inner tube and squash everything up.

dan_b · « **Reply #16 on:** August 31, 2012, 07:38 PM »

do the axle lengths vary, i have just took the bolts back out and took some pictures. the non drive side had about 5-10mm depth to the axle then the drive side had about 15mm maybe a bit more to the axle.

harris · « **Reply #17 on:** August 31, 2012, 07:40 PM »

just bang it back ,the axle should float in the bearings,if you just keep tightening one side itll pull the axle more that way.

dan_b · « **Reply #18 on:** August 31, 2012, 07:51 PM »

so there should be a gap at then end then, on the videos they fit one arm first to the axle then the other but i did them both at the same time. whats the tightening sequence as read a few different things. and on the videos not really clear how to do it. sorry for all the questions thanks

dan_b · « **Reply #19 on:** August 31, 2012, 10:00 PM »

sorted it. centred the spindle and took 3 of the spacers off and tightened back up. got both sides equal and as tight as can get them, with no play and spins as it should.

dan_b · « **Reply #20 on:** August 31, 2012, 10:26 PM »

noticed on the chain there a centre part missing on one of the links, is there a specific brand chain to look out for and how do i size it up? thanks

GaryN · « **Reply #21 on:** August 31, 2012, 11:53 PM »

Quote from: dan_b on August 31, 2012, 10:26 PM

noticed on the chain there a centre part missing on one of the links, is there a specific brand chain to look out for and how do i size it up? thanks

I like KMC chains as they make chains for a lot of people anyway and generally I try and go for a nickel finish as that looks better for longer. If you are running 25/9 gearing on the Arcade then you might want to consider a half link chain as some standard ones don't follow the very small 9T rear drivers very well.

As for the size of the chain if it says BMX chain on the box then you should be good to go.

I think that the last one I bought was a KMC Z510H Premium for about £10 from Winstanleys BMX, you can pay less but you can also pay a lot more.

Not used them myself but a company called YBN seem to make quite a range of BMX chains as well.

Oh, don't forget that you will also need a chain tool as the new chain will be too long so it will need to be shorted before you can fit it, so that will be another £10 or so. I find Chain Reaction Cycles very good for tools.

Hope that helps.

dan_b · « **Reply #22 on:** September 01, 2012, 12:33 AM »

thanks mate have a chain tool in the box so good there, i have been reading to find out a bit more and kmc seem rated. but theres a lot of stories about the half link ones being rubbish. not sure if i need a 1/8th size though.

GaryN · « **Reply #23 on:** September 01, 2012, 03:54 PM »

I thought that BMX chains were pretty standard and are measured as 1/2 x 1/8. I would say that if you don't actually need a 1/2 link chain then not bother as they cost more and I also find them more fiddly to split/join.

You might find that your original chain has details stamped into the links such as 410 or 510, you could then perhaps search those numbers and see what comes up size wise.

dan_b · « **Reply #24 on:** September 02, 2012, 09:03 PM »

been out for the first time today and enjoyed it was hard work though and started getting used to it.

Author Topic: new to bmx - bit of help please (Read 3870 times)

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