MTB stem height / tube extenders...?

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esuhl
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MTB stem height / tube extenders...?

Postby esuhl » 8 Mar 2018, 9:47pm

I've tried to adjust my MTB handlebar height with various lengths and angles of stems, but I really need an extender to increase the stem height.

There seem to be two main types available. Ones with external bolts that clamp on to the steerer tube, and ones that are a cylinder with a diagonal cut that clamps to the inside of the steerer tube, like these two:

https://bbbcycling.com/uk_en/bhp-21-extender
https://bbbcycling.com/uk_en/bhp-22-tubeextend

1) Are they safe? Is one type better than the other in terms of safety?

2) How much do they raise the handlebars by? Most of the products I've seen don't seem to specify, or they give a fixed number (like 67mm in one of the links above) -- is that a minimum, a maximum, or just a fixed unchangeable height increase?

I'd probably want to increase the height by around 2 to 5 cm. Hard to know exactly, until I give it a go... :-/

Any tips, advice, or recommendations? :D

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horizon
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Re: MTB stem height / tube extenders...?

Postby horizon » 8 Mar 2018, 10:14pm

Google stem raiser (Delta is a popular make).
There is also an extended stem raiser available now.
There are also stem converters which take an old threaded headset and turn it into an Aheadset style.

https://deltacycle.com/stem-raisers/ste ... d-adapters

I cannot work out what your first link is (it looks like a converter).

There is some adjustability but IMO all are brilliant anyway and do the job. You may have to lengthen your cables but that is the worst of it.
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

peetee
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Re: MTB stem height / tube extenders...?

Postby peetee » 8 Mar 2018, 10:21pm

It depends entirely on what style of steering system is fitted to your bike. The traditional threaded system has a stem that is angled and drops down into the steering tube. The modern 'ahead' system has a stem that is straight and clamps around the steering tube.
Current status report:
Latter side of fifty and feeling less than nifty.
Too many bikes on pegs and too few miles in the legs.

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horizon
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Re: MTB stem height / tube extenders...?

Postby horizon » 8 Mar 2018, 10:37pm

peetee wrote:It depends entirely on what style of steering system is fitted to your bike. The traditional threaded system has a stem that is angled and drops down into the steering tube. The modern 'ahead' system has a stem that is straight and clamps around the steering tube.


I had a vague recollection that there are two types of Ahead stem raisers but I could be wrong. Once the OP has confirmed his stem type then I would recommend either a converter + Delta (for threaded) or just the Delta for the Ahead. The longer Delta can be used in either case. I wouldn't recommend an old style threaded stem raiser (even if you can get one).
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

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robgul
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Re: MTB stem height / tube extenders...?

Postby robgul » 9 Mar 2018, 7:16am

Of your two links the first one is a "stem converter" enabling a bike with an old-style quill stem to use a modern bolted-on stem - the second is an extender to fit a modern a-head type fork steerer and lift the stem - two different animals.

What sort of steerer does your bike have is the first question.

The other question is how high and why do you want to raise the bars - if you are looking at "aggressive mountain-biking" I'd think twice about an extender as strength/stability could be compromised. [Recent experience with a customer at my shop using an a-head extender was "interesting" on a downhill ride]

Rob

0xymoron
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Re: MTB stem height / tube extenders...?

Postby 0xymoron » 9 Mar 2018, 8:38am

If you have an (old-fashioned) quill stem you can just buy a longer stem and move it up and down in the head tube until you get the height you want.

If you have a modern aheadset stem you want a stem riser. Satori is a good make, and if you search on EBay and/or Amazon you can find plenty of people selling them, e.g.:

https://www.ebay.co.uk/itm/Satori-1-1-8-Bike-Handlebar-Riser-Stem-Raiser-Extender-Bicycle-HEADS-UP4/322545047382?epid=563371906&hash=item4b192ed756:m:mPwUMa9qFjpQKNUskEpL4aw

Or something cheaper:

https://www.ebay.co.uk/i/272611599845?chn=ps&adgroupid=46781198765&rlsatarget=pla-378868093347&abcId=1129946&adtype=pla&merchantid=101459015&poi=&googleloc=1006826&device=c&campaignid=974199509&crdt=0

You adjust the height on these things by just adding or removing the spacer rings.

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horizon
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Re: MTB stem height / tube extenders...?

Postby horizon » 9 Mar 2018, 9:38am

0xymoron wrote:You adjust the height on these things by just adding or removing the spacer rings.


Not exactly. The stem raiser has to be the top item on the steerer. There is some adjustment for the stem up and down the raiser (not a lot) but it cannot go lower or higher. For further adjustment you have to either get an extended stem raiser or cut your steerer tube - the spacers are irrelevant to the raiser.
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

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531colin
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Re: MTB stem height / tube extenders...?

Postby 531colin » 9 Mar 2018, 1:28pm

https://bbbcycling.com/uk_en/bhp-21-extender
On this extender you do exactly remove the spacer rings to get the height you want....the smallest ring is usually 5mm.
I would always mount the stem on the biggest spacer(s)
Caveats........you will need additional regular Ahead spacers
It only works on a steel steerer.....alloy steerers are too thick wall, so it won't go in the hole!
I prefer them to the "exterior" type stem raiser, because they are neater and they can't go crooked, provided you have a decent length in the steerer. You can even araldite them in, if you want.
But the bolt is a tricky one.....a single long bolt acts as both the "expander bolt" for the wedge to fit the thing, and also the female thread for the top cap. Don't break it, or its a whole new extender you have to buy.....they are strong enough for real world use, but I'm quite sure people break them as well.
The "rings" of course make up the difference in diameter between the outside and inside diameters of the steerer

0xymoron
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Re: MTB stem height / tube extenders...?

Postby 0xymoron » 9 Mar 2018, 3:22pm

horizon wrote:
0xymoron wrote:You adjust the height on these things by just adding or removing the spacer rings.


Not exactly. The stem raiser has to be the top item on the steerer. There is some adjustment for the stem up and down the raiser (not a lot) but it cannot go lower or higher. For further adjustment you have to either get an extended stem raiser or cut your steerer tube - the spacers are irrelevant to the raiser.


Having fitted the body of the stem raiser on the steerer tube (thereby having achieved an approximately 70mm increase in stem height),the precise height of the stem is fine-tuned by varying the number of spacers fitted between the stem and the raiser itself (thereby achieving another potential 0 - 70mm increase in height).

esuhl
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Re: MTB stem height / tube extenders...?

Postby esuhl » 9 Mar 2018, 6:34pm

Thanks all! So much to think about... :-)

robgul wrote:Of your two links the first one is a "stem converter" enabling a bike with an old-style quill stem to use a modern bolted-on stem - the second is an extender to fit a modern a-head type fork steerer and lift the stem - two different animals.

What sort of steerer does your bike have is the first question.


I have an Ahead steerer, but I think you can use the quill/ahead adapter types on a ahead steerer too.

robgul wrote:The other question is how high and why do you want to raise the bars - if you are looking at "aggressive mountain-biking" I'd think twice about an extender as strength/stability could be compromised. [Recent experience with a customer at my shop using an a-head extender was "interesting" on a downhill ride]


The stem that almost fits is a 90mm 35degree one. The reach is perfect, but the handlebars are 1 to 3 cm too low (at a guess). Maybe I could use a flatter stem and raise it by 7 to 10 cm or so.

I mostly ride on the road and "commuter-grade" bike paths. Sometimes I go off-road, through forests or heathland and ride pretty hard and fast over rough ground. Once a year, I'll ride a proper MTB trail, but I take it fairly easy. I never race or try to "push myself" to take risks. I've fitted a wing mirror and pannier racks and never wear a helmet because it doesn't seem necessary.

Would a tube extender be able to cope with this level of abuse, do you think?

531colin wrote:https://bbbcycling.com/uk_en/bhp-21-extender
On this extender you do exactly remove the spacer rings to get the height you want....the smallest ring is usually 5mm.
I would always mount the stem on the biggest spacer(s)
Caveats........you will need additional regular Ahead spacers
It only works on a steel steerer.....alloy steerers are too thick wall, so it won't go in the hole!

Ah -- I think it's an aluminium (alloy?) steerer. But... why would I need additional spacers -- where would they go? :?

531colin wrote:I prefer them to the "exterior" type stem raiser, because they are neater and they can't go crooked, provided you have a decent length in the steerer. You can even araldite them in, if you want.
But the bolt is a tricky one.....a single long bolt acts as both the "expander bolt" for the wedge to fit the thing, and also the female thread for the top cap. Don't break it, or its a whole new extender you have to buy.....they are strong enough for real world use, but I'm quite sure people break them as well.
The "rings" of course make up the difference in diameter between the outside and inside diameters of the steerer


It does looks neat. But it doesn't look as safe as the ones that clamp on the outside of the steerer. :?:

So the external-clamp type would protrude unless I set the handlebars to the maximum height...? That would be annoying as it would stop me mounting my mobile phone to the bike... Could it be safely sawed down to the right length with the right tools...?

esuhl
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Re: MTB stem height / tube extenders...?

Postby esuhl » 9 Mar 2018, 9:08pm

Okay... After a lot more thinking... I'm going to get a BBB extender and some spacer rings and have a play with the height.

- https://www.amazon.co.uk/BBB-TubeExtend ... m+extender
- https://www.amazon.co.uk/Quality-Alloy- ... s_sp_1_vtp
- https://www.amazon.co.uk/Ultimate-Hardw ... rer+spacer

It occurs to me that, to avoid a protruding steerer tube, I might be able to turn the stem upside-down so it's angled downwards. I can see myself needing to buy yet another stem to get the fit just right!

:-)

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horizon
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Re: MTB stem height / tube extenders...?

Postby horizon » 10 Mar 2018, 12:21am

0xymoron wrote:
horizon wrote:
0xymoron wrote:You adjust the height on these things by just adding or removing the spacer rings.


Not exactly. The stem raiser has to be the top item on the steerer. There is some adjustment for the stem up and down the raiser (not a lot) but it cannot go lower or higher. For further adjustment you have to either get an extended stem raiser or cut your steerer tube - the spacers are irrelevant to the raiser.


Having fitted the body of the stem raiser on the steerer tube (thereby having achieved an approximately 70mm increase in stem height),the precise height of the stem is fine-tuned by varying the number of spacers fitted between the stem and the raiser itself (thereby achieving another potential 0 - 70mm increase in height).


We must be talking about two different things. I am looking at one of these:

https://deltacycle.com/stem-raisers/ste ... iser-black
I have two doctors, my left leg and my right leg. (G. M. Trevelyan)
PS I always wondered why the YHA HQ was called Trevelyan House. :)

0xymoron
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Joined: 28 Sep 2010, 8:10pm

Re: MTB stem height / tube extenders...?

Postby 0xymoron » 10 Mar 2018, 8:30am

So the external-clamp type would protrude unless I set the handlebars to the maximum height...? That would be annoying as it would stop me mounting my mobile phone to the bike... Could it be safely sawed down to the right length with the right tools...?


Yes, unless you use the maximum extension on the external clamp-type of raiser you'll have a portion of the raiser body extending above the top surface of the stem clamp. Personally, I wouldn't cut the stem raiser body down, although I suppose if you know what you're doing I don't see why it shouldn't work (and if you do cut it down and then decide later you want to raise the stem another cm . . .)

If you really must have the top of the stem clamp flush with the top of the raiser body you'll have to get the correct combination of spacers and stem to achieve what you want. Alternatively, you could combine a stem raiser and an adjustable stem, but that's starting to get a bit heavy, ugly, and expensive.

Don't forget that you've currently (probably - most bikes do) got spacers between the current stem and the headtube, which you can also fiddle with to adjust the stem height (depending on how much steerer tube you have - it's all a it complicated, really).

I've used these types of stem raiser for years and they work very well, and I find them very easy to fine-tune (but then again I don't care if there's a couple of cms of tube extending above the top of the stem clamp).

0xymoron
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Re: MTB stem height / tube extenders...?

Postby 0xymoron » 10 Mar 2018, 8:32am

horizon wrote:
0xymoron wrote:
horizon wrote:
Not exactly. The stem raiser has to be the top item on the steerer. There is some adjustment for the stem up and down the raiser (not a lot) but it cannot go lower or higher. For further adjustment you have to either get an extended stem raiser or cut your steerer tube - the spacers are irrelevant to the raiser.


Having fitted the body of the stem raiser on the steerer tube (thereby having achieved an approximately 70mm increase in stem height),the precise height of the stem is fine-tuned by varying the number of spacers fitted between the stem and the raiser itself (thereby achieving another potential 0 - 70mm increase in height).


We must be talking about two different things. I am looking at one of these:

https://deltacycle.com/stem-raisers/ste ... iser-black


I've never seen a raiser like that that doesn't use spacer rings - it seems a strange design to me, but then I've been using the spacer-type ones for years.

esuhl
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Re: MTB stem height / tube extenders...?

Postby esuhl » 10 Mar 2018, 9:24pm

0xymoron wrote:If you really must have the top of the stem clamp flush with the top of the raiser body you'll have to get the correct combination of spacers and stem to achieve what you want. Alternatively, you could combine a stem raiser and an adjustable stem, but that's starting to get a bit heavy, ugly, and expensive.


I looked at those adjustable stems, but they don't look too safe... In hindsight I should have got one, adjusted it and measured the length/angle for a more solid alternative... instead of buying three stems of varying sizes, none of which quite fits right. :-/

0xymoron wrote:Don't forget that you've currently (probably - most bikes do) got spacers between the current stem and the headtube, which you can also fiddle with to adjust the stem height (depending on how much steerer tube you have - it's all a it complicated, really).


Good point -- I think there is one (or two?). I can't wait till the tube extender and shim rings arrive and I can mix and match all the bits and suuuurely I'll figure out the perfect setup! :P

0xymoron wrote:I've used these types of stem raiser for years and they work very well, and I find them very easy to fine-tune (but then again I don't care if there's a couple of cms of tube extending above the top of the stem clamp).


That's good to hear! To be honest, I've been quite reassured by the comments I've seen from people who use them.