If you change the fork travel length from what the manufacture has on the bike does it affect ride safety etc?
On the Ask a cycling coach episode 214 @Jonathan and the team talked about possibly changing the fork travel on his bike for the Leadville race.
I’m considering changing from a 2016 Stumpjumper comp carbon with 140 fork travel and 67.5 head angle to a Epic Evo 120 fork travel and 68.5 head angle. Well actually I will keep the Stumpy but want the Epic EVO.
My LBS owner and friend said that with the change in head angle and 120mm fork you wouldn’t know the difference from a standard Epic frame with a 69 head angle if you added 120mm fork.
Is this true that one would not know the difference between 69 degree Head angle versus a 68.5 head angle with a 120mm fork? I Don’t like the color on the EPIC EVO and might consider building out a frame of a traditional EPIC to the specs of and EPIC EVO.
If you go longer, there can be additional stress placed on the frame. Some manufacturers (Trek is one) test their bikes with “over-forked” versions that are longer by 10-20mm in some cases than the stock models. If anyone is looking to make a change like this, I highly recommend checking with the manufacturer before doing so. Head tube angle, bottom bracket height and Trail are all impacted. These are not as likely to be a “safety” issue, but will change how the bike performs in a variety of situations. Those changes could be considered safety issues if they lead to undesired ride handling.
If you go shorter, there is not necessarily more stress on the frame. But you will incur changes to head tube angle and bottom bracket height as two of the most notable changes. It obviously steepens the HTA, but also changes Trail. The lower BB height can lead to more pedal strikes (assuming the same cranks are kept) and these can be a real problem in some situations.
Assuming the same fork travel and most people would be unlikely to really feel the difference of 0.5* of HTA change. It also affects Trail, but I still think that is too small of a difference to really notice. The real difference hiding under that in the Epic vs Epic Evo is the additional fork suspension travel. That will most likely be more noticeable in a positive way. It can lead to more supple travel in the initial stroke, and more bottoming resistance on bigger hits.
The geo change as a side benefit to the travel is good for the direction of being a more capable and less tricky bike to ride in more challenging terrain. Add to that the wider tires usually spec’d with this new “Down Country” style bike, and you get into that XC/Trail bike blend that is pretty darn capable.
Thanks, I just wanted to ask the question and hear from another source. I follow the logic of your response and concur. That is mainly why am biased to some of the big name brands as I believe the RnD and testing from top level riders goes into many of the designs they push to us. I think i will just wait until they make an Epic EVO in a color i like versus build up a standard Epic to the EVO specs.
thank you for your quick response
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