ASK RIDE… How will changing my fork affect my bikes handling?
I recently bought a Cannondale Caad9 second-hand and it comes with what I believe is quite a heavy fork. The 2009 CAAD9 has a fork with a 45mm rake. In looking to upgrade and replace it, the ones I’ve looked at all have either a 43mm rake or 49mm rake. Assuming I go with a rake that is less, or more than what i have now, what affect does that have on the bike?
I’ve heard increasing rake provides more stable steering, and less rake make steeing more twitchy? this this true? – John (Chippendale NSW)
John, the 2009 CAAD 9 bike came spec’d with a 45mm offset fork for the 9 sizes that were produced. Depending on the size of the frame the head angle varied in degrees from 72, 72.5, 73 and 73.5 from the 48cm frame to the 63cm frame. The result of this in terms of the trail according to their website http://www.cannondale.com/usa/usaeng/Products/2009/Road/Details/1542-9RA95D_9RA95C-CAAD9-5 is:-
All things being equal a bike with a smaller trail will handle more quickly and I guess in your words twitchy.
You have asked what is the affect of changing to a smaller offset and a larger offset on your bike. Contrary to what you have said an increased offset fork installed in your current bike will in fact reduce the trail and again all things being equal quicken the steering and handling. The other changes are increased front to centre measurement ie the diagonal distance from the centre of the BB to the centre of the fork dropout and slightly longer wheelbase….but nothing that I believe in these two areas that would be noticeable. Just the quicker steering. Again the opposite occurs when you use a smaller offset fork.
As you have not indicated what size your bike is, the affect of every 1mm less or more of fork offset will effectively increase or decrease your trail by approximately 1.05mm with a wheel radius of 335mm. Now if you were able to adjust your head angle at the same time you then go into a completely different discussion.
I have had many disagreements about this point of installing a smaller or larger offset into a frame where the head angle cannot be adjusted. Please refer to the diagram which I found on wikipedia to highlight the point. – Peter Teschner
Peter Teschner is regarded as a ‘Master Craftsman’ by his peers. He has supplied bikes to World Champions on track and the road and Teschner built bikes are the #1 choice by many of the World’s leading professional triathletes, time-trialists, track and road riders. www.teschnerbikes.com
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