Sunday, 17 December 2023

Mountain bike drop bar conversion


This is the drop bar conversion that I've done for my Scott Scale hardtail mountain bike.

This post describes why I did this conversion, what I components I used, and how much it cost me.


Why?

I admit it's a strange-looking bike, and unusual build; a MTB with a drop bar.  It may not be obvious why anybody would want to swap out the flat MTB handlebar for a drop bar.  There are three mains reasons why I did this conversion, which I've explained below:

1)  Wider tyres are faster off-road.
Firstly, over the last few years I've down a lot of testing that has consistently shown that wider MTB tyres are faster than narrower gravel/cyclocross tyres.  Those tests are summarised briefly below, with links to my previous blog posts that describe the tests in more detail:
  • In 2021, I did a back-to-back test around the same road loop, riding my road bike, then my gravel/cyclocross bike, then my hardtail MTB.  The really surprising result from that test was that MTB was actually no slower than my gravel/cyclocross bike.  For both of those bikes, the tyres were reasonably fast tyres in their own category, both scoring quite high on the individual tables of Bicycle Rolling Resistance's gravel and MTB tables.  Because the test was done on a road circuit, you'd think that would favour the gravel bike versus the MTB.  However, the results indicate that the improved rolling resistance of the MTB tyres versus the gravel tyres was cancelling out the less favourable aerodynamics of the MTB (due to wider tyres, the flat bar, the suspension fork etc).
  • Then, in 2022, I performed a virtual elevation test (a 'Chung method' test) for my MTB around a grass field, to determine the optimum off-road tyre pressure.  An interesting observation from that test was how much faster the 2.35" Schwalbe Thunder Burt tyres were than the 35mm Schwalbe X-one cyclocross tyres that I tested back in 2020.  The rolling resistance coefficient difference between them was enormous, equivalent to 30-35W at 15mph. 

  • Then, later in 2022, I performed a similar virtual elevation grass test using my cyclocross/gravel bike which this time was fitted with 40mm Continental Terra Speed gravel tyres.  The aim was to determine whether the CX/gravel bike was quicker overall than my MTB with it's Thunder Burt tyres, to help me decide which bike to use for an upcoming cyclocross race.  Surprisingly the MTB was faster, despite the worse aerodynamics.  This again indicated that the lower rolling resistance of the MTB tyres was outweighing it's aerodynamic disadvantages, to give a net speed benefit.
All of this showed that wider tyres, especially the Schwalbe Thunder Burts that I had tested for two of those tests, were much faster than narrower gravel and cyclocross tyres, even faster than very good tyres like Conti Terra Speeds. 

That got me thinking, whether the best combination for a fast and light off-road bike would be the wide Schwalbe Thunder Burts coupled with a more aerodynamic bike and riding position.


2)  MTB tyres don't fit into the frame of my cyclocross/gravel bike

Sadly the frame clearances of my Planet X Pickenflick cyclocross/gravel bike does not allow me to fit my Schwalbe Thunder Burts.  Even if I bought the 2.1" version instead of the 2.35" size, they wouldn't fit.  The maximum tyre size for the frame is about 50mm, which is fairly large by cyclocross bike standards, but is not big enough for MTB tyres.

Hence, getting fast MTB tyres onto my cyclocross/gravel bike was unfortunately not an option for me.

Interestingly, around this time, I saw a Twitter post from Tom Anhalt who also said that his favourite gravel tyre is actually a MTB tyre.  He commented that he was looking to convert his gravel bike to take 650B wheels.  I didn't fancy going in that direction though, because it would require new 650B wheels etc.



3) My new full-suspension MTB
The third and final reason that persuaded me to convert my hardtail MTB to a drop bar bike was getting a new full-suspension XC MTB in early 2023.  Until then, I had ridden my Scott Scale hardtail MTB as my 'best' MTB for any fast MTB rides.  However, having bought a nice new full suspension MTB in the spring of 2023, a Specialized Epic Evo, I found that I was then rarely using my Scott Scale.

My Scott Scale hardtail seemed somewhat redundant in my garage, in the presence of the full-suspension XC bike and my gravel/cyclocross bike.  There were few types of rides and terrain where it was a better option than those other two bikes.

It was these three things that persuaded me to convert my Scott Scale MTB to a drop bar bike.  I also had a spare pair of SRAM Rival 1x hydraulic shifters, which I could re-use for my my bike build, helping to reduce the cost of the conversion. 


Components and cost

I had to buy the following items for this build:
  • Ribble Level 3 Carbon Aero Road Bar:    £39.00   [RRP £149.99, no longer available]
  • SRAM Rival 1 Long Cage Rear Mech:    £34.00   [RRP £124.00]
  • 2 x SRAM road hydraulic disc replacement brake hoses:  £75.19   [RRP £92.00]
  • Schwalbe Thunder Burt Super Race 2.25" front tyre:   £52.79   [RRP £68.99]
  • Planet X Selcof Carbon Rigid Fork:   £99.99   [RRP £199.99]
  • Syncros semi-integrated tapered headset:   £15.99   [RRP £45.99]
  • 100mm -> 110mm boost axle adapter spacers:   £7.85   [RRP £8.33
  • Lifeline professional bar tape:   £11.43   [RRP £12.99, no longer available]

I already had the following items spare, so these didn't cost me anything at the time of this build:
  • SRAM Rival 22 11- Speed Shift Brake Lever Set    Already owned   [RRP £532.00]
  • Ritchey Comp 4-Axis 30 degree 60mm Stem:    Already owned   [RRP £42.99]

Note that I only had to buy the front tyre because I wanted to move my old 2.35" Thunder Burt front tyre onto my new full-suss MTB as a rear summer tyre, and 2.35" Thunder Burts were out of stock everywhere.  Hence I had to get a 2.25" version instead.

The total cost to me for the items above was £336.  As shown above, some of the items I managed to get were real bargains, bought at a significant reduction compared to their recommended retail price (RRP).  The total RRP of all the items I had to buy is £702.   If I had to also include the cost of the shifters and stem, which I had already as spare items, the total RRP cost would be £1277.

In summary, at just over £300, I think this was a fairly cheap conversion.    However, if I had to buy all of the items at full price, the £1200+ cost would have been significantly higher.

The Outcome

I'm really pleased with the way the bike has turned out.  Not only was it a fairly cheap conversion to do, but the bike feels great when riding off-road trails.  It feels faster, more forgiving and more comfortable than my cyclocross bike with 40mm gravel tyres, but also faster than my old hardtail on road sections and whenever the off-road speeds are higher.  I feel that for the majority of off-roading riding I do, it's the ideal of bike to be on.

Looks wise, I have to admit that it's a bit ugly and unusual looking, but I'm okay with that.  The weight of the bike is 8.67 kg (19.10 lb), including pedals, bottle cage and out front Garmin mount.

I have used the bike for a few cyclocross races in recent months, and it has performed well, helping me to get better race results than normal.  In a future blog post I'll show more details about these Cyclocross race results.

It's interesting that in 2023, the racer Dylan Johnson has also started to use a drop bar mountain bike for his gravel/MTB Life Time Grand prix Races in the US.  In a recent YouTube video he explains his reasons for using a drop bar MTB this bike and tyre choice, which are similar to mine (although Dylan favours Conti Race Kings instead of Schwalbe Thunder Burts).























2 comments:

  1. Great posts as always, Nick.

    I'm curious if you've had any desire for a grippier tire than the Thunder Burts (which I'm also running in 2.35") on some rides?

    I've been contemplating the Kenda Booster Pro for a trail/adventure bike, which has higher knobs than the Thunder Burts. According to Kenda, it has "a mere 20.1 watts of rolling resistance when inflated to 30 psi under 110 pounds of load." I think this would place it in the realm of the Racing Ralph/Rocket Ron, though I know BRR tests at 94lbs (you'd know better than me how much that impacts the result). Most notable is that, unlike Schwalbe tires, they come in 2.4" and 2.6" sizes — 2.6" being especially interesting as most XC tires don't come in sizes that big.

    Thunder Burts seem unbeatable right now in terms of pure speed, but 2.6" is interesting. If we know wider is faster off-road, where's the point of diminishing or negative marginal returns? Curious to get your thoughts!

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    Replies
    1. Hi Logan, thanks. Yes, there are often times when the ground is softer and the Thunder Burt really struggle. On my new mountain bike, I'm currently running a Racing Ray in the Front and the Thunder Burt in the back. There are certainly days when I've want to have something like a Racing Ralph or Rocket Ron in the back instead, but it's hassle to swap tubeless tyres, especially with inserts. Ideally I need a 2nd pair of wheels.

      That's a really good question about optimum tyre width. I don't know, but I think it probably depends on how soft the ground is and how fast the speeds are (as there is an aero penalty when running wider tyres). For example, I do a beach race most years, with riders running a variety of bikes, such as cyclocross bikes, mountain bikes, and fat bikes (4" wide tyre) bikes. The fat bikes fly across any softer sand, whereas the other bikes struggle, but on the harder/faster sand and the gravel tracks, I get the feeling they struggle to keep up. The winning bikes (always a Dutch team), use drop bar bikes with tyres in the 2.2"-2.4" range.

      As for the Kendas, I've never used Kendas myself and I see that BRR has tested very few, unfortunatley. There are some good discussions about XC tyres on the TrainerRoad Discourse Forum, with several users expressing an interest in the Kenda Booster Pro and how fast it is. As it happens, within the last day one of the regular users, a guy called Joe, has posted the results of some tests he did with Thunder Burts versus Booster Pros. The Thunder Burts are quite a bit faster. You can find the thread here:
      https://www.trainerroad.com/forum/t/xc-race-tire-thread/49967/1098

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