[Closed] I don't think I can get a dropper to fit my bike

If you want to fit a 150mm drop Rockshox Reverb stealth you need at least 215mm from the top of your seat clamp to the saddle rails. The overall length is 440mm so if you need to insert the seat post all the way that means 225mm inside your seat tube then you need another 100mm for the connectamajig before your stealth port (less if you use a plain connector) Adjust as necessary if you have more than 215mm from seat clamp to saddle rails

It also needs to be externally routed. At the moment my riding height measures 150mm from seat clamp to saddle rails. Am I right in saying I need 150mm travel?

This is probably a bit out of date, but it will give you an idea:

At the moment my riding height measures 150mm from seat clamp to saddle rails. Am I right in saying I need 150mm travel?

That's dimension 'G' in the table - you definitely don't want 150mm travel: Only the 75mm Cobra in the table above would fit,

Nope. If you only have 150mm from seat clamp to saddle rails you can't fit a 150mm dropper because you don't have room for 150mm of travel plus the seatclamp plus the collar on the dropper. You may be able to fit a 125mm but I don't know the dimensions you'll have to have a search

Edit: Chart tillydog has provided suggests your choices are limited

edit, what he said^

tbh even a 125mm may be pushing it.

Just a thought - When you measured the gap, was the saddle set at the optimum height for riding on the flat/climbing? Or is it set a bit lower at a compromise height that's OK for some bumpy stuff/down hill (small D, small H) stuff too? - You may have more room than you think if you are OK with the saddle slightly higher on the flat/up hill.

The other way to steal a few mm is to see if there is a saddle with a shorter distance between the rails and the seat surface.

This is confusing me more than it probably should.  I've marked up a photo with the dimensions I have.  The 270mm is rough as I just took the measurement externally without checking how far down I can actually get. I'll check it properly tomorrow

Photobucket doesn’t work...

Based on the info in TilleyDogs chart

Your in-frame length limit of 260mm is the dimension E - all the posts require less space than you have so every post will fit your frame just fine.

However the distance between the top of the seat post clamp and the saddle rails of 150mm is dimension G

only one post (Kind shock Cobra) has a dimension that will fit. All the other posts are longer - even the 100mm reverb requires 170mm - ie if you tried to fit the 100mm travel reverb, your saddle would be 20mm too high.

As explained above, you're not going to get more than about a 3" dropper in there. If it were me, I'd buy a longer one and limit the extension by clamping a cable between the saddle rails and frame.

Why don't you just buy any 125mm post that doesn't have fixed settings and drop it a bit when you're riding? Can't see it being an issue as long as you store it fully extended. No point buying 150mm as it'll be miles too long.

I think I could get away with my seat being another 10 to 15mm higher than 150mm. Would that increase my options? If I'm understanding correctly that would mean dimension G could be 160 or 165mm?

I've got a V1 medium frame and my 125 drop KS Lev fits fine

I’ve got a V1 medium frame and my 125 drop KS Lev fits fine

What distance do you have between the seat clamp and saddle rails mate?

"If I’m understanding correctly that would mean dimension G could be 160 or 165mm?"

Yes. It sounds like it would be worth experimenting with your saddle height a bit to find out what's comfortable for non-technical riding and then re-measure.

The saddle also looks quite tall in the photo, so you *may* gain some space by changing it for a lower one (so you can raise the seat-post a bit to get back to the same height)

I would definitely not go for a post that is too long - you want it to come up to the right height when you press the button without messing about.

What distance do you have between the seat clamp and saddle rails mate?

At a guess (going with the figures in table above) about 190ish as the collar on the post flush with the frame, so maybe a bit too high for your needs. Nothing stopping you running it not fully extended but might be a bit of faff.

Previous to the Lev, I had an eTen which is 100mm drop. Good, cheap dropper BUUUUUUT damn it can be slow to actuate!

I think I could get away with my seat being another 10 to 15mm higher than 150mm

Raise your saddle until your heels can just touch the pedals at full extension without rocking your hips as you pedal. This should leave just a slight bend in your knees when you pedal with the ball of your foot on the pedal, so this gives you maximum power for climbing. You don't want your saddle any higher than this. Then measure from the saddle rails to the top of the seat-tube. That will be dimension G in the table above. You need a seatpost that is shorter than that length.

Raise your saddle until your heels can just touch the pedals at full extension without rocking your hips as you pedal. This should leave just a slight bend in your knees when you pedal with the ball of your foot on the pedal, so this gives you maximum power for climbing. You don’t want your saddle any higher than this. Then measure from the saddle rails to the top of the seat-tube. That will be dimension G in the table above. You need a seatpost that is shorter than that length.

Cheers. I'll have a play about with it tonight

Right. No idea where I got the 150mm measurement from. It's closer to 200/210mm

A brand X XL 150mm dropper is 205mm from bottom of the collar/top of seat tube to the saddle rails according to the CRC Q&A section.

A brand X XL 150mm dropper is 205mm from bottom of the collar/top of seat tube to the saddle rails according to the CRC Q&A section.

That sounds perfect. I'll have a look. Cheers

Shorter cranks will let you run more exposed seat post too.

That sounds perfect. I’ll have a look. Cheers

In fact CRC have the spec diagram on their product page (last picture), it's 211mm.

http://www.chainreactioncycles.com/brand-x-ascend-xl-dropper-seatpost/rp-prod159172

Total length inc mechanism is 458mm

Collar is 33.5mm

Travel is 150mm

From bottom of collar to bottom of mechanism is 247mm

So: 458-247-150-33.5 = 27.5mm which is the height from the top of the post to the seat rails.

27.5+33.5+150 = 211mm 😀

If you need a few more mm, run some shorter cranks, or a lower height saddle, or thicker pedals.

That's the internally routed version, did you say you need an external one?

That’s the internally routed version, did you say you need an external one?

Yeah.  Do they do an external version?

Doesn't look like they do an externally routed one. Any other ones with similar dimensions that anyone knows of?

If you check the table above, you can see which seatposts will fit and then check if there's an external version. For example, a 125mm Reverb will fit and is available as an external version. I don't know about the others off the top of my head, but a bit of Googling will soon sort it out.

Right. No idea where I got the 150mm measurement from. It’s closer to 200/210mm

There you are then! Get yourself a Lev 125mm!

To be honest, I cant see past any KS post as that's all I've used but that being said, I've had no problems with either of them and the Lev has the added bonus of no cable growth on the drop as the cable terminates at the collar, not at the top of the post.

If you check the table above, you can see which seatposts will fit and then check if there’s an external version. For example, a 125mm Reverb will fit and is available as an external version. I don’t know about the others off the top of my head, but a bit of Googling will soon sort it out.

So I'm looking for B,C & D to add up to 210mm? Hopefully I've got my head round this

Not quite but nearly. MAX 210mm

Don't forget you don't have to slam the collar to the frame so if B + C + D (= G) is less than 210, you can always raise the post up to get to the magic figure.

edit: remove formating

Not quite but nearly. MAX 210mm

Don’t forget you don’t have to slam the collar to the frame so if B + C + D (= G) is less than 210, you can always raise the post up to get to the magic figure.

So the Brand X Ascend II has  B(28 roughly) +C(125) + D(33) = 186. Would mean when it is fully down it would extrude my frame by 24mm which is nothing really

CRC does free returns, just try one for fit, nothing to lose.

OP..... if you order from CRC and it's more than £99, PM me and you can have my 10% British Cycling code for this month.

Minimum £99 spend, then 10 % of the total price of purchases.... Just enter code at checkout.

Regarding the CRC returns, the item must not be fitted BUT you can get real world measurements from it and if no good then you can return it.

Good luck!

Not sure how much drop you worked out was needed, but if it turns out to be a low amount FUNN do one with a mere 70mm drop, in CRC clearance for £99 currently:

http://www.chainreactioncycles.com/funn-updown-funn-dropper-seatpost/rp-prod148390

edit: but for that drop length it's only 27.2 & 350mm length.

The magura vyron also has a low stack height for its 150mm if travel. I have about 1mm clearance on my extra large rocket. A reverb would not fit at all.