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I have a Trek 820 2014 26 inch for which I had the lbs convert to rigid fork. The original suspension fork was a suntour m3030 which the manufacturer states has a 63mm travel for my bike size. I lost that fork so I have no idea what the length of the axle to crown of that when I’m seated.

My current fork is actually a decent and durable but has about 375 mm axle to crown. I have my eye on a surly 1x1 in which the 100mm travel corrected axle to crown is 413mm. My fork has a trail that I don’t know the measurement of. So does this surly.

My issue is that my shoulders and neck get easily uncomfortable where I have to sit up on my bike(holding my grips with my fingertips) from time to time on only a 10 mile ride. Doing no hands is twitchy, very sensitive to movements so great care is needed when drinking on the go. I have a different bottle now though so I get to drink only during stops, or stop myself to drink, but still, the fact is maneuvering needs good focus.

Additionally, I have thinner tires now that accommodates 1.8 in tubes. I had no ride problems with the tires on the suspension fork, nor probably the rigid ones.

My question is will a higher front make the ride more comfortable for my shoulders and neck? Could the bike tolerate that change in height structurally?

  • So your bike's geometry is already non standard. Perhaps rider bars or fiddling about with the stem would be cheaper than buying a replacement fork. Wouldn't help the trail factor though. – Criggie May 19 at 6:11
  • Drinking shouldn't need you to take both hands off the bars. Get a proper bottle with a sports cap that you don't have to unscrew to drink from. – David Richerby May 19 at 14:30
  • Sorry for the weird sentence. I do drink with one hand when I still had my sport bottle, but with the rigid fork, it was easy to get off balance. I replaced it with the screw on bottle as it was easier and faster to clean. – SpideyUdaman May 20 at 1:36
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You should not try to adjust your riding position by messing with the steering geometry. Riding position should be adjusted by replacing the stem with one that is longer or shorter of has more or less rise.

However, it sounds like you need a longer fork anyway. 375 mm axle-crown sounds far too short. I put a rigid fork on a 90's 26" wheel MTB that only had 40 or 50mm travel and the axle-crown was 420mm. I suspect you have steepened the head tube angle too much which is why the bike steering is too fast.

It's possible to make an estimate of the crown-axle measurement of the original fork by making some relative measurements on a high resolution image of the bike knowing the rim diameter is 559mm. The Trek archive page of the 2014 820 is here which provides just that. I estimate the axle-crown is is more like 460mm.

  • Thank you! You've answered all of my concern. – SpideyUdaman May 20 at 1:41
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Any bike would virtually be okay when stacked with a fork longer or shorter than the 'recommended' A2C for as long as the result is still within practical standards. It's you yourself (your ergonomics and balance) that limits that range.

Bear in mind that raising your headtube (by inserting a longer fork) can affect many things. Your reach (in reference to the bottom bracket) will be shorter, your stack (BB to head tube height) will increase, and most importantly, your seat tube angle will slacken.

Side effects of these geometry changes are:

  1. Your body will be more upright, which can be either a good or a bad thing depending on your biking discipline.

  2. The bike will feel shorter horizontally (like a laidback cruiser bike). You'll need a longer stem if you want to address that.

  3. The head tube angle will be slacker, which makes it stable but it could also feel a little sluggish.

  4. The saddle will be closer to the rear wheel axle, making it more prone to wheelie-ing.

  5. The saddle height will feel shorter and the seatpost will feel flexier. You'll need to readjust the seatpost length, which will bring your saddle even further back and closer to the axle, making it even more prone to wheelie-ing.

  6. The bottom bracket will shift forward and it might feel a little awkward when pedaling. (getting closer to a recumbent bike)

Despite that, it's really practically negligible if you stay within limits, which (for me and some) is more or less ±20 mm A2C. Yours is a +38 mm (almost twice) A2C, which is in a territory where I'll say in disclaimer-format that "it's up to you."

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    Thank you! I'll stay within limits, perhaps when I do decide to change my fork which I likely will. – SpideyUdaman May 20 at 2:05

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