Tools used for cutting or chasing BB threads are used enough that there is wear of material form them, including that of re-sharpening, can leave less perfect threads. If the tool has wear, the cuts are not as deep and more metal remains than if it was done by a new cutter. A new BB threaded into them may feel more snug and less smooth. Nothing you'll sense if a shop puts it in for you. Chasing the threads in a local shop will usually bring off some metal but resulting in a higher tolerance to the threading specification, and a smoother install.
I doubt your installer had anything seriously wrong going on since a mis-threaded BB would be a bear to actually turn after a turn or two. If the component ended up on-axis and the other cup could even go in it finished being screwed in on the threads There may have been some abuse of the first thread of the part from not starting perfectly on line and that may have produced the drag you witnessed; the component's threading is seldom stronger than the frame's now that the piece we are screwing on isn't the actual race for the ball bearing like the old days. Those ball and cup units had a much shorter length of total threading and could be cross-threaded all the way in, then with a goliath finishing effort, turned just enough more to collapse threads (the frame's or the part's), regain on-axis alignment and finish flush against the frame's BB face. Those destructive outcomes were never appreciated until you or another shop tried to disassemble to service or replace such an installed BB and see the band of resultant missing threads in the frame. They could go on unnoticed for years or be the part that comes loose very quickly, causing a click when pedaling. BB designs have evolved in a way which circumvents the not fully proficient local installation of their parts and distances their manufacturers from frame damage claim situations in or by local shops. Andy Cheatham Pittsburgh On Wednesday, February 18, 2015 at 1:05:24 AM UTC-5, Jeremy Till wrote: > > As a professional mechanic, I would say that there are numerous reasons a > BB might go in slightly tightly or not as easily as a perfect tool video > might show: > > 1. It is true that not all frames from Rivendell are faced and chased > before they are delivered to customers. I had to end up facing and chasing > my Quickbeam when I got it. > 2. Shimano BB's now ship with a thread locking compound pre-applied to > their threads, so there is resistance from that the first time you thread > in a BB. > 3. Even perfectly faced/chased BB shells and BB's with clean threads will > not always thread together 100% smoothly. To a certain extent it depends > on the production tolerances of the BB shell and BB cups, how much > deformation there was in joining the tubes and BB shell, etc. > > If anything, I would take comfort in the fact that it took them a while > and that they backed it out to check things as they were installing it. > They were taking the time to make sure it was done right. The hamfisted > mechanic forces things in quickly and doesn't give it a second thought. > > On Tuesday, February 17, 2015 at 5:28:03 PM UTC-8, drew beckmeyer wrote: >> >> preface: im not much of a mechanic. i can install and adjust most allen >> wrenchy components, but beyond that, i go to a bike shop. >> >> so, i got my hunqapillar frame a few months ago and i got a standard >> issue shimano bb to have installed. took it to a local used bike shop and >> had the guys put it in, since i dont have the tool or previous knowledge of >> how to do this. i watched them and it looked like it was taking some work. >> hard cranking, working it in and out etc. grease was used, but they didnt >> chase it. it struck me as not the easiest/somewhat rough install, but id >> never seen one installed before, so what did i know... >> >> bike rides fine. bb is smooth, no sounds, no wiggle, no complaints. >> >> Cut to me, now, watching instructional videos. i stumble upon a bb >> install video and it seems like theirs went in much easier than mine. this >> makes me nervous. >> >> i call a higher end and reputable bike shop and tell them this story. >> mechanic says "it might just be that it wasn't chased. it might be that >> they stripped the threads and if we take the bottom bracket out, one will >> never go back in again." i ask if what he would do if he was in this >> predicament. "we can check it out, but i would maybe just ride it until you >> need a new bottom bracket because if the threads are gone, we cant fix it." >> >> obviously, this makes me infinitely more nervous and sick to my stomach. >> >> what can you tell me? what would you do? how likely is it that this is a >> deathblow? >> >> >> -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bunch+unsubscr...@googlegroups.com. To post to this group, send email to rbw-owners-bunch@googlegroups.com. Visit this group at http://groups.google.com/group/rbw-owners-bunch. For more options, visit https://groups.google.com/d/optout.
