External BB to square taper conversion

geoff_ss

I turned 77 a few weeks ago and someone's been at the local hills and making them steeper. I fitted my wife's bike with a battery and a front wheel brushless electric motor a couple of weeks ago and she used it today for her usual 50/60 mile Wednesday geriatrics ride and found it to be brilliant. She still had about half the charge left after 46 breezy and rolling miles. I fitted the so-called pedal assist which needs a Hall effect device down by the L/H crank and a disc with 8 rare earth magnets to detect pedal rotation. Riding with a selectable pedal assist is a bit like riding with a back wind but you still have to put some effort in, which she obviously did considering how little she'd taken out of the battery.

I quite like the idea of fitting a similar system to the Kinesis Racelight based bike I built/assembled about 7 years ago. The problem is (possibly) that I have a Truvativ external B/B and the pedal assist detection needs a square taper B/B axle for it to fit properly. Without getting out the tools and trying I'm not sure if it's possible to change over to a sealed B/B and square taper crankset or if the frame is dedicated to an external B/B. Is it as straight forward a job as I think or are there possible snags (apart from expense, that is)?

thanks in anticipation

Geoff

Semantik

Geoff,
I own a Racelight- it will just as happily work with a square taper bottom bracket and chainset as the external cups setup you have now.

geoff_ss

Many thanks for the prompt response, Semantic. I just couldn't remember why I fitted an external B/B when I put the bike together and thought it might have been because the frame design required it. So it's just the expense of replacing a perfectly good component - and probably the rest of the transmission as it's getting a bit long in the tooth like its owner.

Geoff

Semantik

One of these will last at least another seven years:

http://www.wiggle.co.uk/shimano-bb-un55 ... sh-thread/

And I think Spa cycles square taper chainsets with the harder Zicral rings are best value.

http://www.spacycles.co.uk/m2b0s109p312 ... chainrings

geoff_ss

I think 7 years will be more than adequate!

I was just browsing Spa Cycles. I want a triple chainset and I'll replace the 9 speed cassette and chain as well. I'm currently on a 44/32/22 with a 13/25 cassette - I like a lot of medium to low gears and I can pedal the 44x13 at 20 mph if I'm feeling silly, after that I free wheel

I suppose I should change my tag to getting an electric motor instead of pedalling faster! But I still feel guilty.

thanks again

Geoff

cycleclinic

your 77 why feel guilty.

milemuncher1

If I'm still riding anything at 77 years of age, I'll be more than happy.

The Rookie

To put it in a perspective, the external bearings were designed to use the same frame mounting that was already in place for internal bearings which started with cottered axle then square taper (cup and cone) before progressing via ST with sealed bearings to the ISIS, Octalink, powerspline type axles and then HT2 etc.

You are a case were I fully support the use of an e-bike so you can continue to enjoy the sport we all love, I hope I can get to your age before thinking I need one!

geoff_ss

the cycleclinic: Milemuncher 1: Thanks for your support The trouble is, mentally I'm still the 30 years old I've felt since I was a teenager (I was never fashionable!) - Physically, not so much!

The Rookie: Yes, that's what I thought but as it's some time time since I put my bike together and we have external B/B on our Cannondale tandem I wondered if, like everything else, things had changed. Certainly they work very well, though I can't say B/B of all types have been much of a problem even on the back of our various tandems where they're subject to two people's pedalling loads.

Anyway my wife's persuaded me to join her in electrically assisted cycling I fly a lot of electrically powered RC model aeroplanes and have built/converted a few intended for liquid fuel. Most of them consume considerably more power than the legal limit for bikes of 250 watts so I'm comfortable with the concept.

Geoff