Daan Posted February 20 Report Share Posted February 20 (edited) Got this Echo Mk6 second hand with Echo splined cranks and front freewheel. The frame has a Spanish BB. When rotating the cranks backwards (chain stationary), the chain tension varies wildly. So was thinking either a knackered freewheel, or a bent BB axle, or both. As the bike has been run with the freewheel spacer the wrong way around by the previous owner (so the freewheel was completely loose), I mostly suspected the freewheel. Took it apart, cleaned it up, some fresh oil/grease (never want to do that again, took me over an hour to put it back together again with those loose ball bearings and shitty way too loose pawls), and it seemed alright as far as I could tell. At least it runs smoother than it did, but tension still varies. Do freewheels have a tendency to not be round and should I just live with shitty chain tension? Axle seems alright looking at it from the side without drive side crank, but of course a bit hard to tell. Edit: found a Trialtech Spanish isis BB, not in stock obviously, but if everything is broken and bent, this might be an option together with some different cranks and freewheel, if Trialtech actually still make it that is. Edited February 20 by Daan Quote Link to comment Share on other sites More sharing options...
Swoofty Posted February 21 Report Share Posted February 21 It's called precession. It happens to lots of front freewheel setups regardless of the price of the equipment. Since you've got the BB shell alignment, the BB bearings, the axle and the freewheel all able to be misaligned, the chances of a perfectly round rotating freewheel are slim. My OCD really hates it too. On some bikes it's not too bad and on others it's more like "are you kidding me?" Sounds like you have the latter. If you've got a friend with a dial indicator, you can try and align the bearings and the crank axle at least, but even then the freewheel will still be the wild card. Unfortunately I don't know a guaranteed way to fix it, but it is very common at least. Quote Link to comment Share on other sites More sharing options...
Daan Posted February 21 Author Report Share Posted February 21 Sounds quite logical @Swoofty, all those tolerance deviations adding up. Especially with trials parts, we all know they're really precisely machined with proper quality control, ahum So I guess a whole new axle, cranks and freewheel might bring me nothing. Have to turn down my OCD and just view this bike for what I bought it for: a beater to try 20" on. Can't really get on with 20" so far anyway haha. Quote Link to comment Share on other sites More sharing options...
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