Mongoose rebuild project

[ChrisF]

Next I showed Maritz how we test a bearing .... turning it by hand and feeling for "smoothness" vs "grinding" ....

 

 

Front wheel - axle turns PERFECT ! 

 

Rear wheel - axle turns PERFECT ! 

 

 

But I must let him feel a "bad bearing" ....    

 

 

Okay, lets try the other bearings ...

 

Fork top bearing - PERFECT 

 

Fork bottom bearing ---     finally a bearing with some "sand/grit" in it.  not "notchy/bumpy" as a worn out bearing, but certainly some grit in it ..... most likely somebody pressure washed the bike and forced grit into the dust cover .....  NOT complaining, glad Maritz now knows what a dirty bearing feels like.

 

 

Got some petrol and sat down to clean the bearing :

 

1) remove the dust covers

 

2) Washed out all the grease and grit from the bearing

 

3) add some new grease into the bearing, turn, turn, turn ....

 

4) wash out the new grease and the remaining grit

 

5) and this is what comes out of a bearing, thanks to a pressure wash ...

 

 

6) apply grease to the bearing, turn, rub it in again, turn a lot more, rub in again, turn a lot more ..... (dont put too much grease in)

 

7) replace the dust covers, and clean the outside

 

 

PS - my apologies ... just realized Mr Haynes was one special character !  Taking pics during the clean parts of the project is easy.  Not so when working with petrol and grease  .... some nasty gaps on my photographic records ...

Edited April 21, 2019 by ChrisF

[ChrisF]

On a roll .... might as well clean the free wheel hub .... what can go wrong ?    

 

A bike can look super clean on the outside .... but man-o-man, when you start digging deeper ....

 

Even the quick release shows corrosion .... (should have taken the pic before wiping off the surface rust )

 

 

Thankfully a good clean and a bit of grease will solve this.

 

 

And just a bit of cleaning to get rid of the grit on the free body :

 

 

 

 

 

uhm ja .... it is EASY to push some of that grit past the dust seal !!            O-well, nothing but a complete strip down and re-grease ....

 

 

Make SURE to note the exact order of each and every washer and spacer as you disassemble the axle ....

 

 

I even noted the exact distance that the shaft protrudes the nuts on either end

 

 

Obviously be careful to get out each and every ball, clean it all and also clean the bearing surfaces in the wheel

 

 

 

Replace the complete nut-set on the one side, and lock firmly in place as per the dimensions noted at the start.  I had to do this on the free body side, as the lock-set is only accessible on the other side once inserted ...

 

Now take your time to re-grease the bearing surfaces,  place the bearing-balls, insert the shaft, turn the wheel over (making sure to not drop out the shaft), place the bearing-balls after greasing the bearing surface.  Tighten the lock set, and check the bearing "feel" - it should not be tight, but it should also not have any free play.  I tightened it, then place the wheel in the truing stand, giving the wheel a spin every so often .... rechecking the bearing feel.  Pretty sure it is spot on and ready for use.

 

 

 

Dankie tog .... bearings all done.     Time for the next part of the project..... 

 

 

NOTE - obviously take as much care as possible to not get any grease or solvents on the break disc !!  I will be cleaning the disc with alcohol before reassembly.  

Edited April 21, 2019 by ChrisF

[ChrisF]

What a loooooong sloooowwwww week .....

 

 

I dropped off the frame at CBR on Tuesday.

 

Not much else we can do now.

 

I was in Malmesbury today and used the opportunity to pop in at BikeAddict.  Bought the chain stay protector (clear strip), a black water bottle holder, and the "smallest" 26'' spare tube .... hiehie .... can only smile when the young sales-staff dont comprehend the concept of needing a spare tube that packs away "small" 

 

 

On the way back I popped in at Addendorf's ....          DANGEROUS place !!!  Went there specifically for ONE item, which I thankfully remembered to get .... but walked out with a bag full of tools .....  including a nice dial gauge to use with my truing stand 

 

 

Simply had to make it a hatrick   ....  Stopped in at Evobikes for some more nice stuff ..... brake hose sets.

 

 

Now if only I can find a nice "top-cap" ...     Either plain black, with no logos, OR the new SA flag (or a play of lines like the SA flag..)

[ChrisF]

....

 

 

NOTE - obviously take as much care as possible to not get any grease or solvents on the break disc !!  I will be cleaning the disc with alcohol before reassembly.  

 

[ChrisF]

 

 

[IMPACT]

Nice work Chris, some good DIY tips included.

[Beard]

Now thats a good haul!

[ChrisF]

Nice long derailure ... 

 

 

1x .... 

 

 

A few bits and bobs for the full install ....

 

 

 

 

And a nice big dish on a small wheel ...    

 

 

 

1x11, with a Sunrace 11-50 cassette.  

 

 

 

A bit of handtools this weekend ... need to fit the ring gear on the other side of the spider, but then to make "bits" to finish off the cogg neatly ...    

 

 

A BIG thanks to Mark's Workshop and his staff for all their assistance with this project !!   

Edited April 25, 2019 by ChrisF

[DJR]

You really are doing this the right way! Impressive! 

[ChrisF]

So what was the thought process behind the gearing ?

 

 

Personally I am still very much in favour of a 2x system .... simply provides the best combination between ease of use AND the maximum range between "climbing gears" and "top end gearing". 

 

But considering price and ease of use ....

 

Price - Coming from a 3x system it is cheaper to go for a 1x than to go 2x 

 

Ease of use - Let's face it, an 1x is simply thee best in terms of ease of use. 

 

 

Let's not kid ourselves ... the above is for the benefit of the bank-manager ...     

 

An 1x just look GOOD !       

 

So the call was made to go 1x ..... which kick started another host of questions ...

 

1x10 ? ... very limited range of gearing

 

1x11 ? .... the normal 11-42 does not offer much more than the 1x10 stable.  Going for the 11-50 results in a range similar to the SRAM Eagle NX, with two gears in the middle having a slightly bigger step.  BUT, going Shimano or Sunrace means that the standard x9 free body hub can be used without any extra work.  Yes, a new shifter and new derailure is needed.  You can go for a complete Sunrace 1x11 kit, including shifter and derailure.  Or for a few rand extra get the Shimano XT shifter and derailure with the wide range Sunrace cassette.

 

1x12 ? .... now you need to start by changing the free body hub, possibly a new hub with a wheel re-build .... these projects can get very costly.  All this to get the same climbing ratio and 10% extra top end ....  This hardly makes sense for a "kids bike".

 

 

Okay so we settled on going 1x11, with the Sunrace 11-50 wide range cassette.  BUT, this begs the question - what ring to use in the front ?  There simply is not one answer that works for everybody !!  Fortunately we ride often, and I KNOW what hills Maritz encounter, I also know what gearing works for him and how far he gets up the various hills with the gearing that is available to him.

 

However, this gearing of 24-36 by 11-34, is on a 24'' bike.  And the new gearing will be on a 26'' bike.  So the "ratio" has to be adapted for the wheel size .... You can do some engineering studies to get to grips with gear ratios, or you can use one of the many websites that aim to help you with this, such as - http://www.ritzelrechner.de/

 

 

Playing with the options the 50 gear on the Sunrace matched with a 32 ring gear provides a marginally better climbing gear than what Maritz currently has - allowing for the change in wheel size.

 

The chart also shows that we loose out about 10% on the top end .... BUT at his age we have never used the top speed on the trails, so not a decider.  IF this was an issue, then a 34 ring would solve the speed, at the loss of some climbing ratio.

 

 

TIP - if you want to go down this road, take note of the gearing you use for top speed and how often you need/use this.  Also do some hills after an hour of good riding, now note the gears you use for a nice steep hill, you now have a benchmark of the gearing that applies to YOUR legs and trails.

Edited April 26, 2019 by ChrisF

[ChrisF]

Waiting for the frame .... probably another 10 days ..... and I certainly dont want to rush a master-piece ! 

 

 

At least this affords us the time for detail work.  One of these little detail pieces being trying to finish off the spider properly ....

 

This wont work - the ring is too far to the right.  It needs to be bolted to the other side of the spider.  BUT, that would result in a nasty little step .....

 

 

Worth playing a bit and seeing if this may work ....

 

 

 

 

 

 

 

Next step is to speak to Mark, and to check if these bolts are fine, or if I should get slightly longer bolts.

 

EDIT - for clarity - the ring gear is now firmly attached to the inside of the spider (same position the middle gear of the 3x was).  This little sub-project was to dress up the "step" where the large ring gear was on the 3x setup.  This is what it looks like without the "bits" finishing it off -

 

 

 

Then to decide :

 

1) Do I keep the natural colour, and just apply a clear coat ?

 

2) Do I paint these "spacers" black ?

Edited April 27, 2019 by ChrisF

[Mongoose!]

All force now only on crank bolts with no support from spider?

Edited April 26, 2019 by Mongoose!

[Mongoose!]

All force now only on crank bolts with no support from spider?

Aaaa saw now, your spacers are on outside.

[DJR]

Mongoose revamp-95.jpg

 

 

Very nice result that - makes a great cosmetic improvement 

[Stretched@Birth]

I ground off the 4 stubs where the small ring bolts on to. My sons chain sometimes drops (need a clutch derailleur), then the chain gets stuck between the bb axle and the stub, resulting in me having to remove the crank to get it out.

[ChrisF]

I ground off the 4 stubs where the small ring bolts on to. My sons chain sometimes drops (need a clutch derailleur), then the chain gets stuck between the bb axle and the stub, resulting in me having to remove the crank to get it out.

 

Thank you for the heads up. 

 

EDIT - Stubs shortened     I drilled out the inside of the stubs in steps, reducing the amount of metal to be ground down.  Finished this off with a bit of grinding, sanding disc on the grinder.

 

 

We did get the XT clutch derailure.  Interesting to note that this derailure has two clutch settings.  One for a 2x setup, with a moderate pre-load - more than a standard derailure.  On the alternate setting for a 1x the pre-load is VERY stiff !

 

 

Mark also pointed out that for these "kids setup" it is worth it to off-set the front ring slightly towards the larger cogg at the back, by playing around with the BB spacers.  The kids spend a lot of time on the larger ring, add to this the shorter chainstay of the 26'' and the chain angle gets hectic .....

Edited April 27, 2019 by ChrisF