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Chapter Two : Bottom bracket swap and chainline woes
Submitted by Sturdly on Sat, 12/09/2006 - 08:45
Well, all the components and tools arrived from Harris yesterday. Order was complete including the grade 25 bearings. It came well packaged and everything was as advertised. I'll be ordering from them again if my LBS doesn't have what I need.
The crank removal went smoothly thanks to getting the specialty tools. Specifically the Shimano lock ring socket and crank puller. Both were Park tools and appear to be of a quality level that will allow me a lifetime of part time use. I did run into a bit of a snag when trying to loosen the pedals. A stock 9/16" wrench is too thick to fit between the crank arm and the pedal. Lucky for me I had a thin old 19/32" wrench which barely fit but saved me having to spend another $16 or more for a specialty pedal wrench. If that had not worked I probably would have ground down a cheap 9/16" rather than spend that extra money.
Before removing the old crank and gear set I measured the distance from the outer lip of the BB housing to the inner chainring it was 5/16". I did this to keep the same spacing and help ease the derailer adjustment. The old ring set was a 42/32/22. The supplied ring set is 48/38/28 a huge difference . Should this gearing prove too tall for my hill climbing needs I will convert to an IPS stoker crank and lower gearing if Allan has not come up with that 11 tooth drive sprocket by then. Luckily my derailer is a mid range Shimano MTB so it will barely fit. The cheaper Shimano MTB will only fit a 42 max ring size. I did have to move it up the seatpost almost 1/2" just to get the crank/rings on the BB spindle. The conversion to bearing and cone from cartridge BB was uneventful and again quite quick as I purchased a pin wrench and a lock ring wrench.
After tightening down the drive side crank I measured and the spacing dimension, it was reduced to 3/16". I did a quick front derailer adjustment and have found two more things to address. First the derailer will not drop the chain to low gear even when adjustment is maxed in that direction and second which was no surprise, the chain is a good six links too short. So time to get some BB spacers and pick that 1/8" back up and also a new longer chain is in order.
I don't want to appear obsessed with BB issues but the chain line and proper shifting is critical given that is the drive mechanism for both me power and the E power on this ride. Had I chosen a hub motor all this would be a non issue.
There you have it. Some minor issues that are just time sinks, nothing to panic about but things that will stretch out the conversion time. Glad I'm shooting for a Spring completion including upgrades and de bugging.
Lesson learned, anything other than a go hub is likely to take longer than expected.
One other thing to keep in mind is that I have no real bike wrenching experience. Mechanically inclined with auto and old motorcycle experience am I. Hints and tips from experienced bicycle wrenchers are welcome.