[saruti]

I've changed my DH bike from a sunday to DHR a year ago, and I still fill I whold be more comfortable on a shorter chain stay.
I was thinkin about excentric BB.
or maybe cutting the BB tube in half and connecting another one to it. alittle backward....
what do you think?

 

[gemini2k]

I'd start with cutting and reattaching with some epoxy. Home Depot should have some appropriate strength stuff. Just make sure you set it up in a clamp with some pressure to hold it together till it sets. You might have to cut and attach a few times until you find the optimal length though. Don't give up, soon that bike will be PERFECT for you. This has been done by a lot of people, trust me, it's 100% safe and legit.

I've changed my DH bike from a sunday to DHR a year ago, and I still fill I whold be more comfortable on a shorter chain stay.
I was thinkin about excentric BB.
or maybe cutting the BB tube in half and connecting another one to it. alittle backward....
what do you think?

 

[ritche]

1. Drill holes in your DHR swing arm to move rear axle closer to BB or.

2. Do a franken custom dh bike: DHR front triangle and sunday rear triangle. Monster garage!


seriously.

Hey rear axle to BB, 0.15 inch difference, how big is that!, 3.81 mm!

Im sure DW considered it on the new DHR.

sunday: 17.25 inches
DHR (new): 17.4 inches

angleset in reverse will steepen fork angle = shorten the wheelbase.

ask turner bikes if they have shorter swing arm for DHR, or if they can make a custom swingarm for you.

 

[saruti]

I’ll start with the epoxy
now seriously, I do feel the different between the sunday and the DHR. so it really bothers me.
When I changed the head angle of my Sunday in 2006, it was a new thing. And look at it now…
I’m sure it can be done to the BB too.
I love the bike. And how it handles everything. I already shorten the top tube with eccentric headset.
And I’m sure I will like it better with shorter chainstay.

Thanks for the humor guys

 

[norbar]

Change your riding position to compensate for the different weight distribution and it will be ok. Trust me I've been on a few bike with way longer CS. Though with that I'd just drift it all day and stop complaining

 

[buckoW]

I'd start with cutting and reattaching with some epoxy. Home Depot should have some appropriate strength stuff. Just make sure you set it up in a clamp with some pressure to hold it together till it sets. You might have to cut and attach a few times until you find the optimal length though. Don't give up, soon that bike will be PERFECT for you. This has been done by a lot of people, trust me, it's 100% safe and legit.

Trick stuff Exzentriker BB? http://www.trickstuff.de/de/products/exzentriker_KL.php However, doing this might compromise your strategic anti squat portfolio.

Frame with shorter stays like a Gambler or Demo?

 

[saruti]

buckoW
this is what I was thinking about.
how much does it move the bb back?
I cant read this .... (german?)

thanks

 

[buckoW]

Looks like 3mm. I like short chain stays too.

 

[Kanye West]

So this whole idea is retarded. But here's a solution that would be mechanically possible.

If you know a skilled (and patient) machinist, you could make some cups with the threaded flange offset to one side. They would have to be external bearing cups.

The only way you could keep them clocked with respect to one another would be to determine where in the rotation the threads on the frame terminate, and make the threads on the BB cup accordingly. Like I said, find a patient machinist, and I don't think BB threads are single-start threads. Haven't looked in a while.

Then you'd also need some kind of a locking mechanism on it, because the offset would want to make one of the cups rotate out, and the other to tighten. So, good luck with that.

Then you'd also need to find a way to shift your chainguide rearwards a bit. Again, good luck with that.

If it's really THAT important to you, get a custom swingarm made. Or get a different bike. Or just shut up and ride.

 

[ocelot]

I don't get it... Moving back your BB only changes its position in relation to the length of the bike. Your chainstay is going to stay the same. Different chainstay lengths is going to give you different suspension kinematics.

 

[gemini2k]

I don't get it... Moving back your BB only changes its position in relation to the length of the bike. Your chainstay is going to stay the same.

Your chainstay length is the distance from the center of the BB to the center of the rear axle. Moving your BB back in the frame will change that distance. It will change the handling and suspension dynamics as well.

It's changing more than just its "relative position"

 

[weedkilla]

Move your feet 3 mm back on the pedals. May sound silly, but as I ride clipped in I can do this in a repeatable way and I swear it makes a difference.

 

[Kanye West]

Move your feet 3 mm back on the pedals. May sound silly, but as I ride clipped in I can do this in a repeatable way and I swear it makes a difference.

This is actually very true. Really only applies to riders clipped in though.

 

[ritche]

try an offset seatpost, cheaper and readily available.

 

[ocelot]

Your chainstay length is the distance from the center of the BB to the center of the rear axle. Moving your BB back in the frame will change that distance. It will change the handling and suspension dynamics as well.

It's changing more than just its "relative position"

I disagree.
You're just changing the position where your center of gravity will be located. Which would make the bike ride really wacky, as if you're riding off the rear the whole time.
From what I understand, the OP is talking about making a device that attaches to the BB, and moves the crank axle towards the rear, to achieve a virtual BB position.
This does not change anything with the suspension kinematics as the suspension arms remain the same length.

 

[saruti]

3 mm is really nothing and not worth all the headache....