b-stone issues
to sean, and whoever else reads this that’s a better mechanic than I…
my bridgestone has been having two issues that I cannot resolve without a full teardown and alot of cursing. maybe some smart reader can help me. i’ll mail you a ping pong sized ball of bee’s wax for your troubles, always handy…
issue 1: weird rumble strip feeling pedaling at about 15 mph. the bike slightly shakes and vibrates as though riding over really small and closely spaced rumble strips. guess: hub bearings? Am Classic grease guard hubs, regreased every few months with park grease, shimano 8 speed cassette, sram 8 speed chain (new, cassette not new) TA cranks and rings, new rings, 30 year old arms, new phil BB, suntour derailluers…
Any ideas? I’ve never felt it on anouther bike, and it is only present at certain speeds, but mentally it feels like the power is being drained into the vibrations, and it feels rather unnerving.
Issue 2: Suntour VGT derailluer, rated to at least a 30 tooth rear cog, wont stay in the granny/big cog combo under load, at all. I would maybe blame it on the old cassette, but its the 30 tooth, not the 15, so what gives? Mark suggested too short a chain, but that only makes sense in the 46/30 combo, besides i just put a new chain on and measured it right…
The beeswax is organically grown, and i scraped it off the porch floor from some melted candles. It still works great, and is pretty clean too. I use it all the time.
1. does it rumble when you’re braking only? not braking only? uphills? downhill? pedaling? not… where do you feel it? In your hands mostly? seat? Is the front end loaded? Does it only do it occasionally? Can you force it to happen? if so, how? Does it mellow out again at higher speed and does it ever happen at higher speed.
It sounds like you’re headed in the right direction. Start with all the bearings. I’d start at the headset. Make sure it’s adjusted properly, that the bearings aren’t “indexed”, and pull the fork out to see if you can pull the lower cup out by hand. Over time, both of my B-Stones ovalized at the lower cup and needed shimming.
If the problem is in the wheel bearings, it *should* turn up in the stand as well. Check for side play, listen to the bearings with your ear on the seat etc… Somewhere in my memory I have a notion that AC hub bearings are dookie. Can’t remember if it was just the super weight weenie ones though.
Check EVERYTHING. Start looking for cracks just to make sure there aren’t any. My guess it’s the headset. My RB does something similar when the HS isn’t a little snug. I’ve got a King shimmed into the HT, so you know it doesn’t align properly and have to find middle ground between removing the shudder and a HS that binds.
2. Hard to diagnose without seeing/hearing it. Is your derailleur hanger aligned properly? A twist tends to show itself on the larger cogs. I’d say check for a twisted chain, but sometimes it’s hard to see a slight twist. Often a twisted chain will work in the stand, but not under load. Again, is this something that has worked in the past, but isn’t working now? Maybe it’s time to start replacing components. Did both of these things start at the same time? Maybe pull the rear axle and make sure the freehub body is tight.
If I think of more, I’ll post it.
P.S. This wouldn’t happen to a TIG welded bike
ha. cory mentioned that the am classic bearings were crap too, which maybe i buy, but they always seem smooth in the hand. i’ll tear the hubs down though, and regrease the fh. the hs is tight, i just checked it. its a campy record OR, which is the most gigantic threaded headset ever, stack height wise. the shimmy never happens when i am braking, basically just under hardish pedaling, ie lower cadence, between 11-15 miles per hour, but not every time.
replacing components? i upgraded to the suntour from a 105… maybe a new cassette is in order: i have an 8 spd modified to a 7 speed on a 9speed hub with weird spacers so as to allow me to run the 46/26 combo.
i think the hanger might be slightly twisted… or perhaps the cage of the derailluer, as it didnt happen when i had a 105 on there. i thought it might have to do with the lack of a spring loaded top pivot, but i ruled that out, as the vgt was supposed to be a wide range touring mech. ack, i’ll just have to tear it all down and beeswax everything. annoying cause my 650b trek goes in for brazeons this week.
thats for all the suggestions. whats yer address? i’ll mail yer wax.
My memory is shitty, so this may not be the case, but I seem to recall my old XC Pro derailleur not having a floating upper pulley. IMO, the floating pulley is one of the marvels of the 20th century. If your upper pulley don’t float, it’s much more critical to have your hanger aligned as close to perfect as possible. Maybe throw a floater on there to see what happens. I promise I won’t tell anyone.
I don’t think I deserve the wax until your shuddering is solved.
One other question…how bad is the shudder? Is it of the magnitude that it affects handling, or is it just a strange thing you can hear and lightly feel?
If it’s really light, I suppose it’s possible that your upper pulley is riding on the cogs. I’ve had that happen with the combo of not enough B tension and too long a chain. It sounds like what you’re describing and if both of these problems started at the same time, it could explain them both away.
I have a similar drivetrain combo on my Fuji right now, Suntour freewheel with a 30 tooth cog, a 42 tooth chain ring up front, and a Suntour VGT dérailleur. When I built the bike, I did have to do some tweaking to the dérailleur hanger with a crescent wrench to adjust the chain line and get everything running true. I also had trouble keeping the rear dérailleur in granny gear under a hard load during climbing or acceleration. However, since I’m running down tube friction shifters, I found that tightening up the friction screw on my rear shifter fixed the problem. Nice and tight now and no popping out of low gear unexpectedly. Are you running a friction or index setup on your bike? Also, how wide is your bottom bracket? If it’s too wide, that may be giving you a really weird chain line when your in granny gear in the rear and the middle chain ring up front. As far as the vibration you’re experiencing, I get that same thing on my newer Trek 1000. You’re right, it’s only at certain speeds and under certain conditions. I haven’t really bothered to investigate it because it’s so subtle and I’m able to easily ignore it. Anyway, good luck with fixing your issues!
matt, i think the hanger is slightly tweaked. i have a hanger alignment thing, i’ll have to fix it. i have friction shifters but they are shimano barcons, and are uneffected by how much you tighten them, unlike my other bike’s suntour shifters. my bb is a 121 on a TA cyclotourist crankset… thats as low as you can go, i have less than 2mm clearance on either stay.
sean, i checked the rear hub bearings, they are knackered. annoying since the hubs were new when i got the bike, (NOS) and i put only about 1500 miles on them, with two grease changes. i’m thinking phil wood freewheel hub replacement or 105… phil is only 20 bucks more, at cost… heavy as sin though. phil is nice cause you can run a 6 spd, almost dishless.
Phil gets the beauty points, but if you’re really after serviceability, get the Shimano or find another hub with cup and cone bearings. I’ve thought for years that I was alone in my distaste for Phil wood stuff until my friend Adam brought it up out of the blue. Didn’t you and I already have this conversation? Phil uses (good) non-adjustable cart bearings. When they die, you bang out the cartridge and replace them. The thing is, they’ll develop play in them after 1000 miles or so but they won’t be dead, so you’ll just deal with a loose wheel forever. I’m half tempted to send you the Phil front wheel off my B-stone. Marvel at it’s looseness.
FYI – the mill is up and running and I just got in from mitering a few tubes. Sweet. FYI#2 – Do you remember how I ran five cogs on my King SS hub on the trials bike? with a little work, the stack of six big cogs on an XT cassette will get on there too. I so badly want to be your six speed buddy!