I got these on a bike last night. the guy told me he welded the spider to the arm because it kept on coming loose. when I got it home I noticed it looked like there were 2 left crank arms because there was no mount on the drive arm to hold the sprocket. Then the more I looked the drive arm was threaded for a right pedal and the spider didnt have a hole for the crank bolt either. Can some one please shed some light on this subject for me.

Ouch, ugly. Can't help you though.

That's how the Group one cranks are set up

The arm is pressed to the power disk

I'll get you some pics tomorrow

Brian

OK tonight LOL

doesnt look to be a very good design...I guess thats why they only made them for a year though...

I luv that Master Brian...

Forget my last post about the welding, I can see now that someone has done a crazy weld that's difficult to fix.

Having a set myself, I can tell you that the drive arm doesn't have a drive bolt that locates the spider.

It was a weak design that relied solely on a splined chromoly crank arm permanently pressed on to the splined spider. Here's a pic that most people haven't seen....well some people.....



Now we can see the working bits.

With the chromoly spline being stronger than the aloy spline, the alloy spider became loose. The crank arm and spider cannot be separated until you grind off the pressed ring binding the two together.

Obviously I went ahead and ground the bugger off, but that was only so I could satin polish and clear anodise the spider while the crank arms get re-chromed.

I haven't done those services yet but here's what I'd do put them back together.

Fit em....



Clean up the welding mess the best you can until it looks like the picture.

I plan to lathe up a special alloy washer that is large enough to cover the damaged area and add greater clamping power to the spider.

In this pic I have used a pair of large metal washers to illustrate what I mean....



If I machine a single alloy washer, the repair would be hard to notice, particularly after the components have been chromed and anodised.

The repair should leave plenty of clearance around the bottom bracket area and be subtle.



The repair still doesn't solve the overall design flaws of the group1 cranks, I wouldn't start street riding or attempt any serious aerials. It should be suitable for a daily cruiser and most flatland tricks.

I'll give this repair my personal thumbs up.




Good luck!

i want your hat roberto!!!

coming up next..... Tech tips on how to get a hat like Roberto's.

Just kidding.

Yeah, even Roberto's expert advice won't help.............unfortunately they are to far gone..........just send them to me and I'll dispose of them for you..

LOL, serva...... and then, once your done having roberto fix em for you, you can then send em back my way for a test fitment