Retro Attraction

[ninarin]

Hi,

I'm new to the forum and I thought I would introduce myself with a question.

I love my old Zaskar frame but there is quite a lot of flex in it.

When I'm riding up a steep hill you can see the BB flex as you put torque through the crank.

I have been told by a few mates that this problem has been designed out over the years of development even in alloy frames.

Is this true?

I ask this question because I have been thinking of changing my frame, both for this reason and to get a frame with a calliper mount on the back. But I don't think the calliper mount is a good enough reason alone to change.

 

[FluffyChicken]

My question back would be. Does it matter ?

 

[Pyro Tim]

Flex is what makes bikes fun. Modern bikes generally don't, and have a cold feel. I ride steel retro bikes because they flex, and reduces the need for suspension.

My understanding is that the old Zaskar's were quite stiff, and if you have lots of flex, you may have a problem, but don't quote me on that, I'm no expert

 

[MikeD]

If you want a new frame, just buy one. No need to go looking for spurious reasons to do so

 

[drystonepaul]

I have been told by a few mates that this problem has been designed out over the years of development even in alloy frames.

Seems an odd comment to make as all frames will have some lateral flex at the bottom bracket area when you stomp on the cranks.
Zaskars have always been one of the stiffer frames in that respect.

One thing that has made quite a difference is the types of BB on newer bikes.
The old style square taper BBs have a relatively narrow spindle which is more prone to flex than the later and wider Octalink and ISIS type BBs.

Moving onto Hollowtech 2 type BBs which have an even larger diameter BB axle and widely spaced external bearing cups. These types are alot stiffer under pedalling load.

I'd suggest that the increase in stiffness on newer frames owes more to the changes in BB designs rather than the way the frames are made.
Obviously this doesn't necessarily include carbon frames can be made to have greater lateral stiffness than metal frames.

If your Zaskar seems really flexible I'd check spoke tension too, as a poorly tensioned rear wheel can give the impression of excessive pedalling induced flex.
Then perhaps consider upgrading to an external type BB and crankset.