Numb hands on cyclocross bike
 

Hello. Last year I got a Fuji Cross Comp cyclocross bike. I like it a lot but am having trouble with fit. When riding my hands go numb easy and my lower back feels a little strained on longer rides. My road bike feels much better. What fit changes should I try to relieve my hands?

Numb hands and feet are indications of blood capillary & nerve damage caused by high levels of insulin in your blood for sustained periods of time. Google "peripheral neuropathy." You might be prediabetic. You can diagnose it yourself with an inexpensive over-the-counter blood glucose meter using the finger prick test. The condition can be reversed by dietary changes but if you ignore it you'll cause lots of tissue damage and risk leg amputations, blindness, strokes, kidney and heart disease. Do you eat lots of carbs like breakfast cereals, bread, pasta, chips, and pizza? The human nutritional requirement for carbs is zero. Your ancestors rarely ate any carbs until the past few generations. So for example if your distant ancestors were Scandinavians they only had the opportunity to eat a few handfuls of wild berries near the end of summer. Think of the traditional natural diets of Sámi and Inuit people.

Set up your cross bike exactly like your road bike.

I'm pretty sure it's not that as I don't have problems on my road bike. They are different bikes so that's why I'm having some trouble with set up. I'll try to put them next to each other again and see if I can find a difference to change on the cyclocross bike.

Saddle tilt. It does not take very much of a downward tilted saddle to increase your hand pressure. Check your seat tilt with a level with your bike on a flat surface.

You can have a look at the Numb Hands post here: https://www.bikeforums.net/road-cycl...l#post12953035

Look at horizontal saddle to BB measurement. Look at reach.

Thank you for the link. I compared my two bikes this morning and the differences were more obvious than I would have thought. The cyclocross seat was up a little higher and the bars are lower and the reach shorter. So I lowered the seat a little to match my road bike. I will probably need a longer stem. The cyclocross stem is super short and +6 degree. My road bike stem is much longer and +8 degree.

Hopefully you measured pedal axle to saddle top rather than just looking at the 2 bikes. CX bikes normally have a higher BB. And how about that saddle for-and-aft measurement compared to the BB? A difference there was my main suspicion. I know nothing about CX fit theory, but these people do: https://www.velonews.com/news/cycloc...ross-bike-fit/

My takeaway from that is that you want your hands even lighter on the bars on the CX bike.

I guess its a little more complicated. I was looking at the specs for the bike stock, but I bought it used and am sure the stem is not stock. The stock stem was 90mm and +7. The stem on it of course has no sizing.. But looking at pictures of stems it looks like it must be around +35 degrees and 60mm. So I want a stem that is longer and will be a little higher. Any guess what size I might want to try? I was originally thinking like 100mm and +7, but would that keep the bars up higher than the current stem?

Yes I measured from the pedal to the top of the saddle. Not sure how I would measure the saddle compared to the BB. These are my bikes btw. Fuji is size 49 and Felt is size 54.
https://www.wiggle.com.au/felt-z75-disc-2015/
https://archive.fujibikes.com/2008/Fuji/cross-comp3

With the bikes on a level surface, or just in the same spot sequentially, drop a plumb bob or just a small weight on a string from the saddle nose. Measure between the string and BB.

The link I posted says that a CX bike should have a TT the same length or longer than your road bike. Your CX bike is 2.5mm shorter. Thus your CX stem should be at least 25mm longer than your road stem to get that recommended fit. 5cm size difference is a lot smaller.

I found this interesting calculator.
Stem Comparison Tool | yojimg.net
Still not too sure what size stem I might want to try. Assuming the current is 60mm with 35 degrees, a 90mm with 17 degrees would have 38mm more reach and 4mm higher.

I changed to the 90mm with 17 degrees and it does seem to feel a bit better. I'll see what I think after a few more rides.

You might also consider moving your seat back a little