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Old 10-18-09, 06:27 AM   #1
erbfarm
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turning a stem around

I need to shave a couple of inches off the top tube of a mtn bike frame I have and the only way I can think of to do it is to turn my stem around and point it towards me. Any danger in doing this? I know it looks ridiculous. I will probably end up throwing trekking bars on the thing as that would give me the closer reach I need, but I'm still curious about turning the stem around. thanks!
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Old 10-18-09, 06:42 AM   #2
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Turning the stem backwards can be very dangerous.
Why not replace the stem with something like this?

A much safer option.
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Old 10-18-09, 06:49 AM   #3
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Most recumbents have a steering axis similar to what you propose and they are a bit more
squirrely than the standard steering axis ahead of the head tube but 'very dangerous' is
a bit presumptive. One difference is weight distribution, on the bent it is back where on
the DF it is more forward, which might enhance the squirrely aspect of steering til you get
the hang of it. Moustach or superman bars might be another approach. RonH has a distinct
point.
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Old 10-18-09, 06:55 AM   #4
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RonH, what exactly is that a picture of? and do you have a link to it?
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Old 10-18-09, 07:01 AM   #5
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Quote:
Originally Posted by erbfarm View Post
RonH, what exactly is that a picture of? and do you have a link to it?
http://www.nashbar.com/bikes/Product...1_10000_201514

There's also these.
http://www.jensonusa.com/store/produ...felt+Stem.aspx
http://www.jensonusa.com/store/produ...tubb+Stem.aspx
http://www.jensonusa.com/store/produ...+Pro+Stem.aspx
http://www.pricepoint.com/detail/127...tumpy-Stem.htm
http://www.pricepoint.com/detail/175...Timer-Stem.htm

Do a search at some of the online retailers to see what's available.
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Last edited by RonH; 10-18-09 at 07:07 AM.
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Old 10-18-09, 07:04 AM   #6
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RonH, what exactly is that a picture of? and do you have a link to it?
The picture is a downhill stem. There are several of those that have very short extensions.

I've got some other questions:

Since you seem to think that your top tube is significantly too long, I'm wondering about stand over clearance. You might be able to "cheat" a little on stand over clearance with a road bike. If you ride off road at all, I wouldn't recommend doing that with a mountain bike unless your family is complete.
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Old 10-18-09, 07:26 AM   #7
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well, top tube length is always an issue for me as it is for most women. I've got long legs and relatively short arms so while the 19" frame size fits me well the 56 cm top tube length is way too long. My best bike set up so far is a 52 cm Sequoia road bike frame which has a 52 cm top tube. My 2nd best set up is my Terry road bike which is a 53 cm frame w/ a 53 cm top tube. I'm trying to set up a winter commuter and have been looking for a 16-17" mtn bike frame which I'm assuming would give me the 53-54cm top tube length that is in my comfort zone, but frames in those sizes seem to be in very short supply on CL in this area at least and what i have in the barn is a 19" trek mtn bike frame w/ a 56 cm top tube and I was going to try to make that work if possible.
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Old 10-18-09, 08:15 AM   #8
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I understand.

I've had good results fitting women by choosing a frame size that has the right top tube length and raising the saddle and handlebar whatever amount is necessary to make it right.
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Old 10-18-09, 08:59 AM   #9
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i understand.

I've had good results fitting women by choosing a frame size that has the right top tube length and raising the saddle and handlebar whatever amount is necessary to make it right.
+1
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Old 10-18-09, 09:52 AM   #10
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My 15" Mongoose has an effective top tube measurement of almost 56.5 cm. 17" KHS = 59cm

Trek's current lowend hardtails' 13" size have a 52.4cm, which seems like it's in your ballpark.

Back in the olden days, my MTBs had shorter front center and longer rear triangle dimensions than most of the ones made from the mid 90s 'til today, so looking for some late 80s MTB frame might be a good bet.

Just for the heck of it, I'd go test ride one of Trek's small frames, and try to judge if one of those with riser bars would work for you. They also have a women-specific line.

At 5'6" with a 32.5" cycling inseam, you'd think I'd have the same problem, but my long monkey arms make up for my short torso to some extent.

Last edited by LesterOfPuppets; 10-18-09 at 09:58 AM.
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Old 10-18-09, 03:35 PM   #11
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thanks for the tips, guys. And I'm partial to 80's mtn bikes anyway. In fact, I've got a really nice 1985 Stumpjumper frame that I just love (18" chainstay and all) but it's got the dreaded 56 cm top tube on a perfect 52 cm frame. So I'll be selling that one off as soon as I post a pic of it on CL. It's actually snowing here right now so I've been in a bit of a rush to build up a winter rider, maybe I should start looking on ebay for an older frame. I just really like the local economy thing of CL though.
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Old 10-18-09, 04:01 PM   #12
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So, what about turning a stem around? I saw this post earlier, before any responses, and I was wondering too. One comment says it`s dangerous, one makes reference to recumbents, whose geometry is very different and even more mysterious to me than DF geometry, and one comment mentions a few types of bars that put the rider`s hands way back without really changing the position of the clamp, which seems to me like a different method of achieving the same result as a zero length or negative length stem. Is there a functional difference between swept back bars and super short stems? What happens to steering when a setup goes outside of say 70 -120mm stem lengths?
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Old 10-18-09, 05:00 PM   #13
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It would probably be better to move the seat forward on its rails
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Old 10-18-09, 05:13 PM   #14
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If a top tube is several inches too long, the frame is obviously WAY, WAY too large for the OP. The correct advice is to get the correct size frame!
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Old 10-18-09, 05:16 PM   #15
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Guys, re-read the part where she mentions that she can't find a suitable frame at the moment and wants to use a frame that she already has. Not to mention that she has unique fit issues so the regular fit frames don't fit well on her in any case. It's also for use as a sloppy weather bike, not something to win races with. So there's nothing inherently wrong with a bit of franken'biking in a case such as this.

Moving the seat forward would mess up the overall body balance and try to shift too much weight forward onto her arms. Those old tyme mountain frames were set up with more agresive angles in the first place. It's not like today's mountain bike geometries that often have a pretty laid back seat tube angle. Granted SOME fudging on this aspect to tune the riding position to the rider is always a good idea but I don't think she wants to be adjusting it more forward than she needs to try to make up for a long top tube.

Using one of those short downhill stems or other rugged short mountain stems set backwards would be fine. There's nothing dangerous material wise with such an arrangement since those parts are so grossly overbuilt to resist all the crashing that is common. And used on a sloppy weather commuter they'll never see even a fraction of the torture they are designed to withstand.

From a steering feel dynamic standpoint it'll feel a bit funky at first but again I don't see it being dangerous. Your grips will end up at a point that is no worse than what you get with many easy upright riding hybrid setups and certainly the final hand position would not be back as far as we see with those pull back beach cruiser bikes. So while there would be a bit of getting acquainted with the feel of the new hand arc that's all you'll get. There's certainly nothing at all inherently dangerous about this since you're just altering where your hands sit in space compared to the front end and not the rake or trail of the front end geometry. Various bar and stem shapes are just a way of achieving this goal. None of the components are going to suddenly crack because they are used backwards in this application.

Just a thought. If you do get one of the short stems keep in mind that it'll have a negative rise if mounted backwards. For this reason you may want to look at the short ones with a 45 degree rise so you still retain about a 35'ish degree rise when it's facing backwards.
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Old 10-18-09, 05:52 PM   #16
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http://boston.craigslist.org/gbs/bik/1426625896.html
http://providence.craigslist.org/bik/1420325934.html
http://boston.craigslist.org/gbs/bik/1417596745.html
Its a little bit of a hike to any of these but not too ridiculous. The Trek in CT would be my choice.
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Old 10-18-09, 06:41 PM   #17
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So, what about turning a stem around? I saw this post earlier, before any responses, and I was wondering too. One comment says it`s dangerous, one makes reference to recumbents, whose geometry is very different and even more mysterious to me than DF geometry, and one comment mentions a few types of bars that put the rider`s hands way back without really changing the position of the clamp, which seems to me like a different method of achieving the same result as a zero length or negative length stem. Is there a functional difference between swept back bars and super short stems? What happens to steering when a setup goes outside of say 70 -120mm stem lengths?
I don't think a backwards stem would be dangerous. I'd start in a grass field to get a feel for it first.

A shorter stem would be different than a long stem and can be a bit twitchy, especially at slow speeds, in that the length of the arc of handlebar movement required to move the wheel one degree is shorter with a shorter stem.

I'm with the guy that says backward stem just places your hands in a different spot and drops the bars unless you got a highrise stem to conteract the HT angle.

I have cruiser bars on a MTB that put my hands about a foot back and a foot up from where they are on a flat bar. The rearward weight shift doesn't present any huge problems. I still like to lean forward on fast sharp corners just to aid front tire grip.
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Old 10-18-09, 07:30 PM   #18
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.......A shorter stem would be different than a long stem and can be a bit twitchy, especially at slow speeds, in that the length of the arc of handlebar movement required to move the wheel one degree is shorter with a shorter stem.......
I agree with the twitchier aspect but I don't think it's due to the angular travel of a shorter stem. With forward grip points thanks to longer stems the weight we lean forward with tends to self center the bars. A shorter stem reduces that "self centering" effect. But if you measure the travel needed at the grips to turn the wheel a degree it'll be very close to the same with different stems and the same handlebars. Now altering the handlebar width would be another issue and shortening the width would have a very noticable effect on this. I know I find that things get a lot more twitchy when I rest my hands on the tops of drop bars close in to the stem.

Going with short stems and especially with a short stem turned around the other way will reduce or even reverse this effect. But it's not anything that's all that hard to get used to in short order. Besides, the reduction in wrist loading thanks to the more upright riding position will automatically reduce any side effects by a lot I would think.
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Old 10-18-09, 08:06 PM   #19
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In addition to the other options mentioned, you might consider something like a trekking bar which wraps around backward to create another hand position. I have one that puts the grips pretty much even with the steerer tube on a stem of about 100cm. That's helped out on a bike that has a top tube that's probably 2" longer than optimal for me.

I feel your pain - even though I'm a guy, I have painfully short arms and fingers compared to my legs. The adage that it's easier to make a small frame larger is easier than making a large frame smaller also applies.
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Old 10-18-09, 09:20 PM   #20
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thanks so much for all the great info guys. I was thinking of biting on the Trek 830 frame that's going for $50 near Boston. It's a 16.5" frame w/ a 21.5" top tube. But I was also thinking of using my Trek 800 beater frame w/ my Nashbar adjustable stem on backwards. I think the stem is a 95mm or so and the top tube on the bike is 56 cm. That stem might be enough to put the frame in my comfort zone w/ flat bars or certainly w/ trekking bars. I do have trekking bars on my 18" rockhopper (w/ a 55 cm top tube) and I can ride that bike all day even w/ my hands on the curves of the trekking bars. Well, if you guys say it's not dangerous to turn the stem around, I think I'll give it a try.
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Old 10-18-09, 10:46 PM   #21
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Hmmm... Definitely some food for thought here.

Good luck with your fit, Erbfarm, I hope you find a comfy (and cheap) solution. Oh, and thanks for the interresting topic, too.
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Old 05-18-12, 06:37 AM   #22
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What is dangerous about turning the stem backwards?

Quote:
Originally Posted by RonH View Post
Turning the stem backwards can be very dangerous.
Why not replace the stem with something like this?

A much safer option.
I am a woman with quite long legs and short torso and have struggled with all of my bikes being too long in the top line and not really comfortable to ride. Finally, last week, my brother suggested I try turning the stem around. He'd never done it, or seen it done but it seemed like it might work. I searched and searched the internet for information on turning the stem around and found several posts saying, sure, try it, it looks really awkward but it should work fine. And there were a couple of posts that said it would be 'dangerous'! But without explaining why...Do you have any reasons why you think it's dangerous??
So I turned the stem around on my old Univega Alpina 5.1 (anybody know what year this bike is?) and just had the best ride of my life. Finally a bike set up that fits me! I don't plan to ride off-road, it's just a commuter bike for me, so no steep, rocky trails. It looks really, really weird, but I just love it!
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Old 05-18-12, 07:01 AM   #23
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Very interesting adaptation of an adjustable stem. As long as the bike rides and handles reasonably well no one can argue that it wasn't a good idea. I'm sure you will get a lot of odd looks and questions but what ever it takes to make the bike fit is fine and it certainly will be a conversation starter.
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Old 05-18-12, 07:42 AM   #24
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As long as the bike rides and handles reasonably well no one can argue that it wasn't a good idea.
Ha! Just wait a bit and somebody will argue that it`s the dumbest idea since indexed shifting
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Old 05-18-12, 09:11 AM   #25
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Motorcycle set up is similar to my bike with its stem turned around

I was just thinking about how motorcycles are set up and how odd they would look with a stem pointing forwards!

This picture is (obviously) the typical set up for a dirt bike, and surely they steer and handle just fine over difficult terrain.
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