Cranks hitting rear swing arm

[colinv]

Hi.

My right crank hits the rear swingarm on my 5500 when any huge pressure is put on the pedals, I have been told it is more than likley the main pivot but has anybody any other ideas about how to resolve this?  Cheers.

[Simon]

Assuming this is a problem that has just developed check the Carbon S/arm dropouts as they are commonly known to come loose (both front and rear)the play developed between the bonded dropout may allow the arm to flex excessively laterally (with high pressure applied the chain will try to pull the s/arm closer to the right crank),alternatively check the main pivot for excessive bearing/bush wear,also check where the bearing locates into the frame insert,if they've run loose the bearing can wear and damage the insert.
Simon.

[Hammer]

I had a similar problem once!  I also had to check the bearings and everything for slop, but as the frame was new, naturally there was no slop anywhere.
In the end I found out via the official K2/Pro~Flex tech forum that some of the early frames had a jig problem and the BB shells were bonded a little offset, they got around this by having race face make a special run of titanium BB's with adjustable cups, these were OEM on the first run of 5500's. Special made for Pro~Flex as they had a pro~flex only axle... 110mm instead of the standard Raceface taperlock 113mm (or something like that).

I didnt want to spend that much money on a BB that no longer existed in the correct length...and cured the spacing problem by placing a spacer behind the BB shell to space the BB a little to the right... if you have a frame from the early run and it doesnt have the Race Face Taper Lock (adjustable chain line) BB fitted, then this could be your problem.

If you do place a spacer uner the BB shell, you will find that the crank arm on the other side moves closer to the swingarm, keep adding/removing spacers until they are equally spaced the same distance from the swing arm on both sides.
For spacers I used the spacers from an old cassette, the type you can unscrew the gears off. Make sure you use the alloy spacers and not the plastic ones.

Once with spacers fitted, you might find that the lock ring for the BB bottoms out in the threads inside the BB shell, so I machined some threads off the lock ring to allow it to lock against the BB core.

I use a 68x110 shimano XT BB with special cups and spacers and thank goodness they dont wear out or it would be a nightmare to do it all again!

On my extra Oz that I have for friends and guests, I simply fitted and off the shelf 113mm long axle BB and found a chainset that was a bit wider, the offset is not as pronounced on that bike though, and I think it was one of the last batch made as it doesnt have the Omni-whatever decal on the frame, but it does have the engraved frame number inside the rear shock mount.

I think that when the BB wears out on my 5500/oz/959 I will get a raceface taperlock or similar with adjustable chainline...

Good luck!

Mike.

[Old Proflexer]

an interesting first post - - - - -

your problem sounds familiar as we just had a post on this same subject after a very, very long spell.  

i think it's great that you found us and we have someone who recently returned that has the very same problem with their frame and a ready fix for you.

could you post a few pictures of your frame and the affected area?  love to take a peek at it especially the bottom bracket area.  what number is your frame?  k2 must have had a batch that went overseas a long time ago that had this problem.

that's what this site is all about, exchanging information and helping one another.

where abouts in the u.k. do you live?  how did you come about getting a k2 carbon?

OP

[Simon]

Ah another UK K2 carbon rider,there are a few of us about,some of us have hooked for rides out,if your interested in meeting up with some of us let me know,perhaps we could take alook at your problem while we're at it  
also must point out if this problem has been there from new Hammer may have the solution but if its a new problem that has developed over time its very unlikely to be a jigging problem.

Simon

[colinv]

Cheers for the help, I think I will replace the main pivot bushes and anything else that can be done around that area, I'm in Hampshire and have always wanted a K2 carbon but not too many of them about and one came up for sale so I had to have it.

[Hammer]

Colin,

Try getting in touch with sprucey...

Mark Spruce, he is from your area, The Witterings I think, look him up in the phone book, not sure if he  ever gets in here these days..

or markspruce@aol.com

although he hasn't been active much lately in the email world that I am aware of...

Could also try paging him via the 855 heads.... I think there is a link to that mailling list from

www.proflex.demon.co.uk

or try

www.ukbikestore.co.uk

I think Mark has something to do with that company, when he is not sailling around the world on yachts!


Anyways... Sprucy will be able to jiggle your bike and tell you whats right and wrong...

Mike.

[Simon]

Phone Mark Spruce on 02392 528 932 (UK BIKESTORE) easy guy to get on with,very approachable,met up a few times,I've just converted his Oz pivot to sealed bearings for him,worth contacting just for all your mtb needs.

Simon.

[Sprucey]

Hi Guys,

Sprucey here. Just got back from sailing a 67Foot race boat in Port Fino, Italy. "absolutely hell" but someone's got to do it! The fine italian fare didn't do anything for my waistline either!

I'm based in Gosport in Hampshire and generally ride the South Downs between Winchester and Brighton but can occasionally be found in the French Alps and the Welsh trails.

Currently heavily (very carefully chosen word!) into my road bike as I am riding the Etape du Tour this year - a mountain stage of the tour de France which means that I have a mental mad streak in me some where.

As Hammer said, I am a director and shareholder of www.ukbikestore.co.uk - we are an internet retailer of bikes and accessories. I also am a professional racing yacht crew and sailing coach which keeps life vaied and interesting.

I have met up with Simon and he has done the bearing conversion on the Oz. I alo have an old 856 singlespeed which is still in bits requiring a fork and and brand new Razorback Team.

Be glad to meet up with you sometime.

Best regards,

Mark