Armchair ( and real) engineers to the fore please
I am trying to fit an electric bike kit to my commuter. Its a posh BB mounted engine but the problem is the motor unit clashes on the chainstay. The frame is a genesis IO which has wide chainstays that are undented / round. This is a steel frame. to get the motor unit to fit I would have to put a dent in the chainstay about 6mm deep and maybe 15 mm long. I don't care about resale value.
If you were going to dent it heat it first or not? Use a hammer or a vice?
Ta for your thoughts
6mm dent? That's pretty significant. What diameter is the tube?
Is getting a welder to do something not an option?
I ****ted, errm... manipulated the chain stays on an old ragley piglet frame to accommodate a plus wheelset a couple of years ago.
Seemed to work, and more importantly, I didn't die.
Used proper engineering tools mind. A peice of 4x2 and a 4.5lb lump hammer
tube diameter is 20 mm. Its a completely round tube wheras most bikes the tube is pre dented in this area. Its just where the chainstay bridge joins as well.
What could a welder do? I need the tube to be thinner
Sounds a bit dangerous
But if I had to I'd definitely heat it first and would put it in a vice - more controllable that way
My alternative is a nicely corroded alloy frame with a hole in its seatstay or my lovely Ti frame
I wouldn't be to concerned about doing that, just make sure the dent is't sharp edged to avoid stress risers and you should be fine.
I think...
[quote=tjagain ]My alternative is[s] a nicely corroded alloy frame with a hole in its seatstay or my lovely Ti frame[/s]
you MTFU
Sorry scotroutes I simply am not manly enough since I grew my hair. *flicks luxuriant locks*
Wasn't this an problem on certain Inbreds, and Brant's solution was to hit them with a hammer?
I have dented and filed frames slightly to get stuff to fit. I did it on my Tour de Far to get a 180mm front disc on.
But I wouldn't fit an bike conversion kit to any bike of my own. If I wanted an e-bike, I'd but a proper one. I've never seen a conversion kit that was much cop TBH
I was fitting a replacement motor on a converted bike last week. It had only done about 3000-3500 miles and the bearings were shot, rendering it useless. A Bosch unit will do ten times that without complaint, they just don't wear out.
What bb unit was that doesnt have replaceable bearings pp rendering it scrap.
Wasn't this an problem on certain Inbreds, and Brant's solution was to hit them with a hammer?
Yep, I did it to my old steel 456, Brant said it would be OK. Can't remember if I whacked it with a hammer or squeezed it with a g-clamp but the frame held up fine.
Jermey i guess you have a ebb on the io .
Is that why your trying to mount the motor near the stays ?
Usually they sit forward under the downtube,
Just dent it. But don't heat it.
No EBB on the io - track ends.
Peterpoddy - this is a high quality sunstar so3 unit. Have you seen one of them? Its the only conversion kit that has proper torque sensing like the bosch and has been in use in Japan for many years. Its not a cheapo one and is backed by a proper guarantee - there are a variety of reasons why use a kit not a prebuilt bike for me including it will be swapped between bikes, I want better quality components than you get on prebuilt bikes, I already have the bike etc etc. The unit costs the same as a cheap fully built bosch bike and is of very high quality.
Trailrat - its the back of the motor unit where it sits against the BB face - the IO has such wide chainstays that it will not slide home in any orientation without hitting the chainstay before it butts up against the mating face.
Shandcycles - ta.
I have actually decided to put it in another frame for now
Put a tube onto the chainstay and **** the sacrificial tube with a lump hammer until the chainstay has enough clearance.
I did this to an expensive Ti frame under instructions from the frame builder.
Ta for the advice - upon measuring up for the third time I decided the size of the dent needed was just too much and as the frame was in good condition I didn't want to wreck it.
I have built it all up into an old frame that is basically scrap I got for £15. Caused a few problems as some of the parts didn't transfer over from the genesis. Did get the unit working last night but need a few more bits to make it rideable. the electric drive unit can be swapped onto another frame pretty easily - just needs a new crush washer thingy so I might end upgetting a better frame again for it later.