[sorry, I just realized that I made a redundant thread on this topic a few days ago!]
I have been on what seems like an endless quest for the perfect frame. I don't have the budget for a custom frame, and I don't know what I would want anyways, so I don't mind buying a different off-the-shelf frame every few years. Regarding geometry, my experience tells me that:
1. everything is connected. every 5mm or 0.5 degrees of change in one dimension affects the rest of the bike in subtle ways that don't manifest until you're ridden a different bike for while over a variety of terrain;
2. your body, skill, mentality, and riding style change, so the "perfect" bike for you now might not be so perfect in a few years;
3. everything is a compromise. a bike that is capable at slow-speed rock-crawling is most likely going to be twitchy at speed;
4. different overall ride characteristics are good for some terrain, riders, and ridin styles than others. so the perfect geometry for you might be a major liability for someone else; and
5. despite what people will say, a difference of a degree here and there and a few mm here and there makes a big difference in how a bike is wrangled over the terrain.
That said, I'd like to delve into rear-end geometry and how it affects riding a singlespeed hardtail/ rigid bike.
I am on a bike with a moderately short CS length with a lot of BB drop. that is, the distance from the axles to the BB is more than the average mountain bike. I can make the BB a tiny higher by using a longer fork and get it further from the ground, but the overall BB height and drop is "low" because of the design of the frame and can't be changed much.
specifically, the frame I have now (2016 or so Jabberwocky) has a moderate chainstay length (430mm) and a low BB (68mm.) this means the rear-center measurement is actually about 425mm. I am starting to think that rear-center and front center measurements are too frequently overlooked.
This low-slung bike feels very stable and holds momentum well, but I am staring to think it becomes a liability when I have to stop, suddenly change direction, and lunge the bike over a ledge, which is a constant issue on my local terrain. I am also starting to suspect that i "don't worry about rock strikes" because I know exactly where the pedals are and ride accordingly-- conservatively! I'd like a remedy that, but I don't think I can change any of the components of the bike. I think I want a bike that handles more like a trials bike, but is stable enough to maintain momentum on technical XC terrain.
One way I have been able to wrap my head around this is to take it to extremes. How would a bike handle (pedal strikes aside) with the same CS length and a 100mm BB drop? a 25mm BB rise? What about a ultra-short 415mm CS with a 100mm drop, or a 25mm rise?
The point I am getting at is: what's your ideal compromise between a rear end that turns on a dime, and gets your center of gravity low enough that you don't feel like the bike is going to toss you at speed as it concerns BB drop, rear-center, and chainstay length? (and leaving BB height as an afterthought, for now)
[this is a ramble that will probably be edited at some point.]
I have been on what seems like an endless quest for the perfect frame. I don't have the budget for a custom frame, and I don't know what I would want anyways, so I don't mind buying a different off-the-shelf frame every few years. Regarding geometry, my experience tells me that:
1. everything is connected. every 5mm or 0.5 degrees of change in one dimension affects the rest of the bike in subtle ways that don't manifest until you're ridden a different bike for while over a variety of terrain;
2. your body, skill, mentality, and riding style change, so the "perfect" bike for you now might not be so perfect in a few years;
3. everything is a compromise. a bike that is capable at slow-speed rock-crawling is most likely going to be twitchy at speed;
4. different overall ride characteristics are good for some terrain, riders, and ridin styles than others. so the perfect geometry for you might be a major liability for someone else; and
5. despite what people will say, a difference of a degree here and there and a few mm here and there makes a big difference in how a bike is wrangled over the terrain.
That said, I'd like to delve into rear-end geometry and how it affects riding a singlespeed hardtail/ rigid bike.
I am on a bike with a moderately short CS length with a lot of BB drop. that is, the distance from the axles to the BB is more than the average mountain bike. I can make the BB a tiny higher by using a longer fork and get it further from the ground, but the overall BB height and drop is "low" because of the design of the frame and can't be changed much.
specifically, the frame I have now (2016 or so Jabberwocky) has a moderate chainstay length (430mm) and a low BB (68mm.) this means the rear-center measurement is actually about 425mm. I am starting to think that rear-center and front center measurements are too frequently overlooked.
This low-slung bike feels very stable and holds momentum well, but I am staring to think it becomes a liability when I have to stop, suddenly change direction, and lunge the bike over a ledge, which is a constant issue on my local terrain. I am also starting to suspect that i "don't worry about rock strikes" because I know exactly where the pedals are and ride accordingly-- conservatively! I'd like a remedy that, but I don't think I can change any of the components of the bike. I think I want a bike that handles more like a trials bike, but is stable enough to maintain momentum on technical XC terrain.
One way I have been able to wrap my head around this is to take it to extremes. How would a bike handle (pedal strikes aside) with the same CS length and a 100mm BB drop? a 25mm BB rise? What about a ultra-short 415mm CS with a 100mm drop, or a 25mm rise?
The point I am getting at is: what's your ideal compromise between a rear end that turns on a dime, and gets your center of gravity low enough that you don't feel like the bike is going to toss you at speed as it concerns BB drop, rear-center, and chainstay length? (and leaving BB height as an afterthought, for now)
[this is a ramble that will probably be edited at some point.]