When a bike shop does part of the job and you do the rest

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CharleyFarley

Senior Member
Location
Japan
My six-years old Specialized fat bike needed a new BB so after much deliberating I took it to a bike shop and had a PF30 adapter screwed in. I didn't have the tools to remove the old bearings, myself. I removed the crankset and chain to save them some time and effort, and stripped the bike of all the accessories. Today, I got the bike back.

Now to put everything back together. Started with the crankset and chain, then found no matter how I adjusted the front derailleur, I couldn't get it right. It's a 104º (40C) out there and my fan was blowing hot air at me. I'd heard that getting the spacers right could be a bit of a job, but it seemed like I'd need to move the chain ring closer to the frame. So pulled the chain off, and removed the crankset and adjusted spacers to bring it a bit closer. Put it all back together.

Aaaahhh! Now the chain won't even go onto the smaller chain ring! Must have needed more spacer, not less. So strip it all down again and realized I'd best look down through the derailleur see the small chain ring and to gauge how much spacer would be needed. Got it right, this time, but can't use the preloader because I had one very wide spacer for the non-drive side. Also didn't have enough 1mm spacers to use with the preloader. So rigged up a temporary spacer and no preloader. Ordered more spacers.

I really like the new BB adapter because I can change the bearings when necessary without buying expensive tools to use one time.

I love learning new things, and today I learned more about spacers, and that I would have probably been better off If I'd left the whole thing to the bike shop. I don't mind struggling with things I've not done before, but not when it's 104º.
 
Taking pictures during the dismantling process can save a lot of headaches during the reassembly.
 
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CharleyFarley

CharleyFarley

Senior Member
Location
Japan
Taking pictures during the dismantling process can save a lot of headaches during the reassembly.

I'm not sure it would have helped in this case because I knew how it all went together but I just didn't have the right spacers. The new BB is slightly wider than the old one, having outboard bearings. Thus, the spacers I had were too much. The two on the drive side - a 1mm and a 16mm - were perfect before the new BB was installed so it was necessary to reduce them by using several 1mm spacers instead. My problem was, the mixture of spacers I had just weren't right. If I'd had a few more 1mm spacers I would have been fine, except for not spacing the drive side correctly which caused the front derailleur to malfunction. The chain came off the chain ring when I tried it out even though it seemed fine on the repair stand.

Anyway, I got it working well with one wide spacer on the non-drive side which I cut down to fit. I've ordered a pack of ten 1mm spacers. The price shocked me. With shipping and state tax, a little over $21. I will then be able to remove the one I cut down, and use several 1mm spacers with the preloader, and it'll be like new.

I'm not one to give up easily but because of the heat, today, I came close to taking it to a local bike shop (who doesn't replace 30mm BBs), and let them sort it out, but they would have had the spacer problem, too, and they don't carry the spacers. In the end I did well because of the knowledge gained in dealing with the situation, even if I did dig the chain ring into my hand and cut it. :rolleyes:
 
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CharleyFarley

CharleyFarley

Senior Member
Location
Japan
I get you now.

A number of years ago I did similar on a bike I simply couldn’t get the old bottom bracket out at home. I’ve taken very careful measurements, using vernier callipers, to be able to ensure the chain rings ended up back in the correct place after the swap.

Where would you measure the amount of space needed for spacers? From the chain ring to what? I'm guessing it would be from the down tube to the chain ring. Then subtract the distance from the down tube to the outer side of the bearing. That would leave the distance needed for spacers. Sorry if I'm confusing things; I had to draw this out to see what I'm talking about.

What would have helped would have been to know the overall width of the BB before removing it. Then measuring the new width after the adapter has been screwed in. There would be a difference of a few more millimeters, thus necessitating the removal of a spacer on two on the drive side.

One good thing is, if I ever have to replace the bearings, the drive side spacers I now have, won't need to be changed, and the derailleur alignment with the chain ring won't be messed up. And I can change the bearings, myself, without special tools.
 
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