Bike fitting blues

[sdcoffeeroaster]

I probably started out wrong by buying a medium Focus jam2 C almost two years ago. I think there was a small available. But I didn't know much and the Giant dealer where I got my first bike convinced me I was a medium. So I naturally looked for a medium Focus a few years later. The Jam2 came with a 125mm dropper and I upgraded to a 150mm I got for nothing thru trading. I ran it with it inserted about 28-30mm out of the frame. I used to be 5'-8" when I was younger but probably closer to slightly more than 5'-7" now at age 71, 30" inseam in bare feet and right between a medium and small with most bikes. I did measure 31.625" inseam with shoes today.

Recently I decided to upgrade to a 175mm dropper since it did appear I had room and while it did fit, even running it inserted all the way resulting in a 10mm higher saddle. The Lev Integra with the upper roller bearing results in a 10mm higher stack height which I didn't notice. I didn't pay much attention to this until I developed saddle sores. That got my attention right away and I started down the road of swapping saddles since I had also changed the saddle at this time. Several expensive saddles and saddle sore treatments and much time off the bike "waiting to heal, still" I had an epiphany today,.....dahhhh. My saddle is just too high and maybe I should be riding a small frame! I did order a Lev Integra 150mm dropper which will put me back at my old height minus 15mm or so. Good start. I made a device to measure my leg angle at the bottom of the stroke and it's probably 175 deg with the 175mm dropper and 165 deg or so with the 150mm one I have coming. According to what I've read I should be shooting for another 10 deg less than that. But at least it's less than I was when I didn't have issues. Maybe a 125mm dropper is in my future or even a new bike!

I never paid much attention to this before and just assumed that if my leg was slightly bent at the bottom of the stroke and no knee issues I was OK. I've even looked at two formulas that gave vastly different results. 1.09* inseam and 0.8766*(inseam, mm) + 9.8. The first one says I'm OK right now (NOT) and the 2nd says my seat should be 6" lower....mmmm, I don't think that's right either. So I'm letting a lack of pain be my guide right now. I finally ended up with an Ergon seat that's pretty good but not really the issue as I've realized today. I also have 160mm crank arms so no options there.

 

[flash]

Or maybe the bike manufacturer knew what they were doing in the first place? Possibly the frame was designed around a 125mm dropper post. I have a bike that won't accept anything longer and it's a large. Bike manufacturers do this stuff for a reason.

The 1.08 formula is for road bikes. Not really applicable on an MTB unless you're only commuting on good quality bitumen.

You don't have to have your saddle at full extension on a dropper post. Try seating with it not fully extended for a bit and see how you get on..

Gordon

 

[sdcoffeeroaster]

Or maybe the bike manufacturer knew what they were doing in the first place? Possibly the frame was designed around a 125mm dropper post. I have a bike that won't accept anything longer and it's a large. Bike manufacturers do this stuff for a reason.

The 1.08 formula is for road bikes. Not really applicable on an MTB unless you're only commuting on good quality bitumen.

You don't have to have your saddle at full extension on a dropper post. Try seating with it not fully extended for a bit and see how you get on..

Gordon

Yes I will try a ride set at 125 and 150 today. But not easily hit once you use the dropper so not very practical. There is plenty of "room" for the 175mm dropper even running it down all the way. And the 150 will put me at a 165 deg angle with upper and lower leg. I rode the bike for more than a year without any issues at 170 deg (with the old 150 set 1" out) but the 175 dropper pushed it to more than 175 deg, almost straight. I am trying to change my order to 125mm but probably too late and the seller doesn't have any of those. The 125 puts me right at 155 deg much like this article recommends (150-155): How to set up the Perfect Seat Height on your E-MTB | E-MOUNTAINBIKE Magazine

 

[mark.ai]

Yes I will try a ride set at 125 and 150 today. But not easily hit once you use the dropper so not very practical. There is plenty of "room" for the 175mm dropper even running it down all the way. And the 150 will put me at a 165 deg angle with upper and lower leg. I rode the bike for more than a year without any issues at 170 deg (with the old 150 set 1" out) but the 175 dropper pushed it to more than 175 deg, almost straight. I am trying to change my order to 125mm but probably too late and the seller doesn't have any of those. The 125 puts me right at 155 deg much like this article recommends (150-155): How to set up the Perfect Seat Height on your E-MTB | E-MOUNTAINBIKE Magazine

The "heel method" mentioned in that article you linked has always worked for me - try that as a starting point and compare it to the height you are currently using.

 

[sdcoffeeroaster]

I did a short ride and set the dropper first to 125mm. Felt strange like I was sitting in a chair, 50mm lower than previously. Then I set it to 150mm and that felt good and like a huge load off of my butt, lol. In fact both felt very comfortable but different. Now I understand why I've felt, at times, like I was in danger of going over the bars on even the slightest downhill without dropping the post. I was just too stretched out and failing the heal test a bit too. I think 150mm works but if I can get a 125 dropper I would have some range to adjust things. Either way it's going to make healing and riding again possible. I'll soon have a saddle sale, lol. The Ergon is pretty good and a keeper.