Tuesday, November 15, 2011

Q&A: Higher handlebars & seatpost setback

Q: I hope you can help me, Jim,
I'm trying to make a 1998 Specialized Stumpjumper mountain bike fit me better. I have slick tires on it and I want to ride it on the road. The problem is that it has one of those stem and handlebar arrangements that can only be raised by putting more shims beneath the stem. Right now there are as many shims as there's room for so I can't make the stem or bars any higher.

I went to a nearby bike shop and they told me that I would need to buy a new fork for my bike in order to get a longer top fork tube [editor's note: called the "fork steerer"], and that would make it possible to add more shims to raise the stem and bars. But they said since a fork is so expensive, and my bike is already on the old side, that I should instead consider buying a new bicycle.

Now, I don't know what to do. I like the ride of this bike and it's in good shape from what I can tell - even if it's a little old. I'm thinking the new fork is the way to go, but it doesn't make sense to me that there isn't some way to just raise the handlebars. So I thought I'd get a second opinion from you.

Please help,

The Delta Stem Raiser
A: I'm glad you asked, William, because you definitely do NOT need a new fork or a new bike to raise your handlebars. What you have is a threadless fork and you're right that the way you raise and lower the handlebars is to add and remove shims. You're also right that you can only add as many shims as there's room for on the steerer.

Understand that when the company that made the bike originally assembled it, the fork had a long steerer on it. But, the steerer is cut to the right size for the frame size it's being installed on. And the amount of shim space left is what the company manufacturing the bicycle believes will provide the person who fits the bike enough adjustment.

Since it's not enough for you, and the fork has already been cut, you need a workaround. And a good one is made by Delta Cycle and called a stem raiser (photo; also available from other makers). You can see how it works in the photo. It bolts to the top of your fork providing an additional 3.25 inches of height. Your stem/bar combo will fit right on and you can fine-tune your position, tighten and finally be riding in comfort. And all for a lot less cost and hassle than replacing a fork or buying a new bike.

Important note: If you're lucky, you'll be able to install the stem raiser and put your stem/bar as high as you want it. But, check your cables and make sure they're not too short now and causing binding when you turn the handlebars to steer. If you run into that problem, you'll have to lower the stem/bar until they have the slack they need, or replace the cables.

Important note 2: Some mountain bikes have flat handlebars, in other words, ones with no rise. To sit higher, you can replace the bars with a set that offers more rise. Another approach is to replace the stem with a model that's angled upward more instead of forward so much. One of these approaches will almost always do the trick. Sheldon Brown covers the subject extensively.

Q: Hello Jim!
It's getting cold here in Canada, but I'm still riding. Today I have a question about how you measure seatpost setback? And what's your point of view on zero-setback seatposts?


Zero-offset left / plus-offset right
A: Seat setback has to do with your pedaling efficiency, Clod.

Usually if you look at the specs on the seatpost you're interested in, it will list the setback. But you can get a good idea looking at it from the side, too (photo). A zero-setback puts the seatpost clamp (the part that holds the seat in place) directly above the seatpost. On a seatpost with setback, the clamp is behind the seatpost. (Interestingly, in the early days of cycling we used to mount the seat clamp in front of the seatpost.)

Note that you may find some seatposts that have the clamp directly over the post, but also provide setback. But this type of post is easy to spot because it's bent to provide the setback.

To get the right seatpost for you, you first want to make sure your seat height is correct and then use a plumbline to find the correct fore/aft position for your body. Once you know where the seat needs to be, you can then figure out how much setback you need.

And, in most cases, unless you have a frame that has a shallow seat-tube angle or you have very short thighs, you probably won’t want to use a zero-offset seatpost.

But, if you check your riding position on the seat (instructions), you will be able to figure out what’s best and choose the correct seatpost.

Happy bike fitting!

1 comment:

Jordan said...

Old post but... a comment on zero setback posts. Since the saddle is right on top of the seatpost and theere is less torque created by the seatpost you get less verticle deflection of the post and a harsher ride. Run a setback post if you can.