Bit of a historic ramble first; I have an 18.5/19 FS and HT respectively. Both have 700 low-rise bars and about 25mm of spacers under the Stem, which on both are 80mm 6 degree rise. I’m comfortable with both. I’m 5’11 and 3/4. In case it affects the below, the comparable bikes are Old HT = Genesis Altitude, New HT = Enigma ego Ti. I ride woodsy singletrack 75% of the time.

Recently, I built up the new HT. Now, the sizing for this one goes 15/17/19. I talked to the shop, got measured – 17 was advised. The geometary compared to my old HT is the same angles, HT and TT, just a shorter ST and more heavily sloped TT. Now, from the parts bin I slammed on a spare 90mm Stem, and 25mm rise 630mm (cut) Easton bar.

And here’s where I need an explanation. I’ve ridden it twice the narrower bar felt weired for a bit, but overall, the bike felt much more lively and chuckable compared to my old HT kinda like Jack Russel vs Cocker Spaniel. I’m not sure if thats the bike, or the longer stem / narrower bar.

So – is this the bar, and what will happen if I replace the 90mm stem with a 70 or 80mm, and stick 700 bars on it – and why?

Or, is the shorter ST contributing a lot to the feel of it, and the bar won’t make a great deal of difference?

Ta!

Why do you want to change the bar? That isn’t clear from your post?
Could you not save some cash and confusion and leave it as it is?m

DrP

DrP – I’m trying to understand that myself. The 80mm / 700mm combo on the other bikes is good, so I immediately thought I should replicate it.

But I’m wondering that if I do, how might it change the new bike, I like the way the new bike handles so therefore should I leave it and save the cash…..?

If I could understand how things may change it may help me come to a conclusion…

your hands need to move less distance to create the same amount of wheel movement.

@Sam – but also create less leverage to hold everything straight I’d imagine?

Or, is the shorter ST contributing a lot to the feel of it

ST length doesn’t effect handling.

The smaller ST and TT will be making the bike more chuckable i think rather than the cockpit. I’d hazard a guess that this is cos you’re more central on the bike.

Shortening your stem by 10mm is apparently equivalent to shortening you bars by 20mm so you’ve eaten up 20mm of those shorter bars with the longer stem maing the bar effectively 50mm smaller.

That’s making it easier to turn as said and therefore more twitchy, you may have lost some stability on descents and I’d suggest you need to compare your 700mm bars against the 635mm bars on descents. You may find something in between will feel best descending and won’t compromise your turns on tight switchbacks. I think you’ll end up keeping the stem the same and using some 660mm bars

ST length doesn’t effect handling.

Centre of gravity?

Thanks Thered, that makes sense.

The bike isn’t twitchy or nervous at all. Also, for Trail centres & Surrey / Peaks etc I’d always take my FS as thats my preference for day rides / technical stuff.

The HT is also build light (22lbs) and will be used for short forest singletrack blasts / short races rather than big descents.

So I fear you are right, It won’t be “worth” banging a 700mm bar on it.

@Sam – but also create less leverage to hold everything straight I’d imagine?

I don’t think most people struggle with holding bars straight or the force required to do so. But people have varying ability to make fine adjustments when confronted with two different control arrangements.

Using your own language, it won’t feel any less “jack russelley” 🙂
My guess is the new bike is more agile, and may be even more so with a bit shorter and wider combo than the 90/630.

Been doing a bit similar with my bike and I think I know what you’re talking about. Gone from 70/680 to 70/725 to 50/725. Being moving the spacers above and below, and to further complicate it, I’ve got Uturn forks which add another variable.

I think I’m keeping it as it is for a while. Built the bike about a year ago and think I’m finally happy. It wasn’t the combo I initially expected to be using, but it works especially out of the saddle. Have also moved the seat back too to allow a bit more room on the longer slower sat down climbs.

I like your jack russell term, think that’s pretty good way to describe it. It’s hard to explain , but it just feels easier to move your body position back and forwards within the bike allowing you to “push” through the pedals or front to weight/unweight the front or the back.

There’s more to it than just saying “that’s best” though.
Its about getting it to fit you personally aswell. Body shape – long/short legs, long/ short torso & arms , wide/narrow shoulders all influence the “sweet spot” position.
Trial and error is the only real way to tell for sure.

If I was you I’d experiment a bit with the bars and stems you’ve got on the other bike(s) rather than buying one. Just get a feel for the position before committing cash to it.

Slightly shorter TT and slightly longer stem, in combination with the narrower bars, means that the bike is more twitchy. All 3 of these factors are influencing it to some degree, which is having the largest effect? Hard to say.

If you put wider bars on it will feel slightly less twitchy, as it will again if you put a slightly shorter stem on. The issue you’ll have then is reach, as I’m assuming you’ve got a longer stem on this to compensate for a shorter TT length?

FWIW I’m about an inch shorter than you, run a 17.5″ Genesis Altitude with 90mm flat stem and Sunline 711mm wide 19mm rise bars and I like the slightly nervous/twitchy handling it has, it suits the bikes character very well. That said I used to run 660mm wide bars on it, with a 10mm shorter a/c height fork, and it was very twitchy like that. Maybe just try out your wider bars briefly to see if it makes much of a difference or not…

I’d reiterate that the Stem length is accident as it was the only thing in the parts bin to use at the time.

Thats said, the difference in top tube between the 2 bikes is 0.4 inch shorter on the Enigma, so not much, do I’ve added 10mm to the Stem – effectively then the Seatpost to Stem length is accidentally the same on both bikes.

As Mboy says then, taking into account the weight and material differences which are probably making the Enigma more “snappy”, I guess I only need to try a wider bar, for personal comfort and to slow down the steering – although neither are an issue.

science is –

bike industry creates new fashion = empties your pockets

see also

x10 gearing and 29inch wheels