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my trail bike (130mm) came with a 60mm stem with a 5 degree rise and the first thing I did with it was to replace it with a 35mm stem at 0 rise,I also added 10mm rise to my bars.
To begin with this seemed to work well. I've now been riding for about 6 months and I ride noticeably quicker than when I started, however I've started to wash out at the front a few times recently around corners, crashing quite heavily on dry loose terrain. I know from looking at photos that my weight is too far to the rear and I am trying to address this with each ride.
To try and help, I'm also going to experiement with stem length somwewhere between what the bike came with (60mm) and what I have now (35mm) as well as removing the additional rise to the bars (from 30mm to 20mm)
I know this is an almost impossible question but based on peoples experiances should I go for 40mm or 50mm to begin with?
I will also potentially be going from 35mm diameter clamp to 31.8mm diamters simply because it appears to be more cost effective.
Maybe try taking out some spacers from under the stem first to get the weight further forward.
Err, when my front wheel was washing out it was because I had too much pressure in the tyres.
Have you experimented with that yet?
Have you tried flipping the original stem to -5 and putting more spacers above the stem?
I honestly don't think there's any alternative to Just Fannying About With It. I've never had a bike/stem combo work out exactly like I thought it would.
I did remove some pressure after my most recent fail and it helped alot, I am struggling to get a true reading of the pressure I am at though so I have no idea what they are set to
I've got 1x5mm spacer sat underneath the stem but it looks as though there may not be much room to reduce that as the stem sits over the spacer slightly, as in I can only see about 3mm of the 5mm total.
very helpful, I had not really understood reach until today when I started to look into this and was wondering whether I had reduced my reach by too much based on my initial changes
my head is telling me to go with 50mm stem as it's closer to the original spec but my heart is telling me to try and keep it shorter at 40mm
what I don't want to do is fork out for a new stem only to realise I made the wrong choice whih will probally be the case whatever I decide.
At this stage, sat here covered in bruises unable to ride, if 50mm is more likely to prevent me from crashing again I might go for that
Leave the 5mm there then. Try the original bar then for the same effect.
I know from looking at photos that my weight is too far to the rear
Are you sure it's a stem issue and not a technique issue?
I hear ya, this is my first 'modern' bike and it's kind of bewlidering trying to work out the many variables with so many options now. I had thought bar stem would be an easy one, just go with what I used to have but it turns out bikes have changed alot since I last bought one over 10 years ago
oh it's absolutly a technique issue, I am working on it but in the meantime to try and get a bit more traction on the front while I try and sort myself out I am going to see if a change of the bar/stems helps
however I’ve started to wash out at the front a few times recently around corners,
trails are dryer so more loose stones;
Your tyre pressures have changed;
Your technique has not changed even though you are going faster;
Its all in your head.
@mariner that tool you linked is amazing, it's essentially telling me that the stem I am looking at, at 40mm doesn't change my reach from where it is currently much at all but does put the stack back to nearer the original spec, but that the 50mm stem puts it back to closer on both reach and stack. Think I'll try 50mm first on that basis
There is no correct length, only what works for you on the trails you ride on that specific bike. Just buy a few cheap Brand X stems from CRC and play around.
Also, buy a decent tyre pressure gauge. Write down your tyre pressures and experiment a bit.
Also, tyres do wear and if you've been riding the same front tyre for six months, it won't be as grippy as when it was new. Trying different tyres is another obvious thing. Ask around and see what people use for the trails you ride. A tyre that is brilliant on dry hardpack will probably suck on wet roots.
Also, weather can make huge differences to trails. Your tyres will wash out if you push hard on wet leaves, but the same trail can be incredibly grippy a few days later once it dries out. Soft trails are sometimes the opposite - too dry and your tyres wash out, a bit of rain and they suddenly get really grippy, but too much rain and they turn to mud.
50mm. Don't get sucked into the short stem mantra. Look at riders like Jared Graves or Richie Rude and they're all on 50mm stems. I went from 35mm as the OEM stem to a 45mm stem as I had similar issues to you - sorted it with the 10mm extra. Short chainstays and short stems are a nightmare for front end grip.
My other bike has a 50mm and I wouldn't want it shorter. I can't be learning the new ways of riding at my age. 🙂
thanks for input all, I am going to stick with the stem for now and drop the bars rise by 10mm and invest in a decent pressure gauge
my head is telling me to go with 50mm stem as it’s closer to the original spec but my heart is telling me to try and keep it shorter at 40mm
Agree with the posts above. 40mm is only 5mm/14% longer stem, and an even smaller %-change on your handlebar reach, not sure if anything under 10mm would be noticeable in terms of weight balance.
Steering liveliness is another thing to consider. I was "geeking out" about this recently after reading this article: https://www.pinkbike.com/news/exploring-the-relationship-between-handlebar-vs-stem-length.html I was interested in the effect on handling, just curious rather than having a problem to fix or wanting a change. To summarise... You can measure the effective stem length (ESL) by crossing a string between your grips and then measuring the distance from it to the centre of your top cap. With my 40mm stem, my ESL is 27mm. The handling becomes twitchy as ESL approaches zero, the article says ~20mm is as short as you'd want. So in my case, a 32mm stem (20% shorter) would give a 19mm ESL (30% shorter). And in your case (assuming similar handlebar) going from 35mm to 50mm (43% longer) would increase ESL from 23mm to 38mm (65% longer).
I found the you tube video by Bikers Edge quite interesting.
Just search for "Best Handlebar and Stem Combo" on the Bikers Edge youtube channel. He tests different stem lengths and describes how they changed teh ride feeling.
Skills day
😬
Nobody can give you definite answer on stem length because your bar roll, width and backsweep plays its part.
Make a note of your bar height from the ground and where your hands are in relation to the stem cap bolt, as said above a piece of string from grip to grip is a good way to know we're your sweet spot is for set up on future bikes, once I've found whats spot on I set all my bikes the same unless the head angle drastically changes from one bike to the next.